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Discussion Groups | BasicX | can we have more than 2 PWM ports on BX24P?
Discussion forum for the BasicX family of microcontroller chips.
can we have more than 2 PWM ports on BX24P? - Yuli - Jan 28 6:12:23 2010
Hi BX24 gurus,
The BX24 example code shows that we can configure Pin26 and Pin27 as PWM signal output ports, is it possible to have one more? If so, how can we configure it? Thanks
Yuli
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The BX24 example code shows that we can configure Pin26 and Pin27 as PWM signal output ports, is it possible to have one more? If so, how can we configure it? Thanks
Yuli
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Jan 28 7:55:33 2010
> ... is it possible to have one more?
Yes, an 8-bit PWM on pin 25 is available, too. See the message immediately before yours: http://tech.groups.yahoo.com/group/basicx/message/23237
Tom
------------------------------------
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Yes, an 8-bit PWM on pin 25 is available, too. See the message immediately before yours: http://tech.groups.yahoo.com/group/basicx/message/23237
Tom
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 6 5:37:31 2010
Thanks Tom.
There are two more questions related to the timer1 and timer2:
1. If we use timer1 and timer2 together, we can have maximum 3 PWMs
working together. Are the timers considered fully occupied now? If I
need to generate one additional square-wave using Output-Compare, I need
to use another BX24 right? (The frequency of the square wave is 600Hz,
so I can't use delay() because the resolution of it is about 2ms).
2. I have another requirement which is to generate 3 100Hz square-waves
on a BX24, each with 1/6 period's phase difference from another, how
shall I do it? I plan to make a square-wave output of 600Hz (using one
of your earlier code as shown below) and connect it internally to an
input Pin, say Pin1. Then each edge in Pin1 will change the status of
Pin2, Pin3, Pin4 consecutively. The status of the Pin1-Pin4 will
sequentially be: 1100, 0110, 1111, 0011, 1001, 0000. I'm just concerned
that if the program execution time for each step (about 2 lines per
step) is too large compared to the period of square-wave, the precision
will be lost.
Sub Put20HzOnPin25() Const T2mode As Byte = bx0001_1111 'flip 25,
clear, 7200Hz Register.TCCR2 = 0 'stop Timer2 Register.TCNT2 = 0
Register.OCR2 = 180 '20Hz=(7372800/1024/20/2)=180 Register.TCCR2 =
T2modeEnd Sub
Thanks!Yuli
[Non-text portions of this message have been removed]
------------------------------------
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There are two more questions related to the timer1 and timer2:
1. If we use timer1 and timer2 together, we can have maximum 3 PWMs
working together. Are the timers considered fully occupied now? If I
need to generate one additional square-wave using Output-Compare, I need
to use another BX24 right? (The frequency of the square wave is 600Hz,
so I can't use delay() because the resolution of it is about 2ms).
2. I have another requirement which is to generate 3 100Hz square-waves
on a BX24, each with 1/6 period's phase difference from another, how
shall I do it? I plan to make a square-wave output of 600Hz (using one
of your earlier code as shown below) and connect it internally to an
input Pin, say Pin1. Then each edge in Pin1 will change the status of
Pin2, Pin3, Pin4 consecutively. The status of the Pin1-Pin4 will
sequentially be: 1100, 0110, 1111, 0011, 1001, 0000. I'm just concerned
that if the program execution time for each step (about 2 lines per
step) is too large compared to the period of square-wave, the precision
will be lost.
Sub Put20HzOnPin25() Const T2mode As Byte = bx0001_1111 'flip 25,
clear, 7200Hz Register.TCCR2 = 0 'stop Timer2 Register.TCNT2 = 0
Register.OCR2 = 180 '20Hz=(7372800/1024/20/2)=180 Register.TCCR2 =
T2modeEnd Sub
Thanks!Yuli
[Non-text portions of this message have been removed]
------------------------------------
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Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 6 12:45:19 2010
> ... I need to generate one additional square-wave [] 600Hz...
Yes, if Timer1 is in use generating PWM you cannot normally use
OuputCapture nor any other function that uses Timer1 without
interaction. However, if the processor need do no other work beyond
making these four signals, since the PWMs are being generated entirely
in hardware and need no code once started, you can dedicate the code to
generating the 600Hz output. Using the RTC tick won't, as you say,
provide very good resolution; you can use it to produce 600Hz average,
but it would be very irregular.
I suggest that you simply use a delaying counter loop, like
sub DelayAWhile(HowLongCount as long)
do until not cbool(HowLongCount)
HowLongCount = HowLongCount - 1
loop
end sub
or something similar. Then just toggle a pin in an endless loop with
the delay between them, like
sub Make600Hz()
do
putpin(pin600Hz, bxOutputHigh)
call DelayAWhile(HalfCycle600HzPeriodCount)
putpin(pin600Hz, bxOutputLow)
call DelayAWhile(HalfCycle600HzPeriodCount)
loop
end sub
This will still produce some irregularity due to the processor stealing
time for maintenance each RTC tick, so you will probably see the 600Hz
edges jitter. You can eliminate that jitter by preventing multitasking
by disabling Timer0, which stops the system tick. See
http://tech.groups.yahoo.com/group/basicx/message/21891 . Be careful to
heed the warning to place a pause at startup before you disable Timer0,
though, or you might not be able to regain control of the processor; you
must also do a physical Reset (drop pin 23 or power-cycle), since the
ATN pin won't be monitored.
On generating three-phase 100Hz, outputting a state list as you suggest
should be fine, each step triggered by the code above. To ensure that
all pins change state simultaneously, after you've set the pin direction
register you can output a byte to the port, like
register.DDRC = bx1111_0000 '4 pins as outputs
register.PortC = StateList(n)
See http://tech.groups.yahoo.com/group/basicx/message/22742 for driving
a 3-phase H-bridge for an implementation. Of course, you can also use
an external shift register to clock a single output bit through six
steps, each delayed by one-sixth cycle.
Tom
------------------------------------
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Yes, if Timer1 is in use generating PWM you cannot normally use
OuputCapture nor any other function that uses Timer1 without
interaction. However, if the processor need do no other work beyond
making these four signals, since the PWMs are being generated entirely
in hardware and need no code once started, you can dedicate the code to
generating the 600Hz output. Using the RTC tick won't, as you say,
provide very good resolution; you can use it to produce 600Hz average,
but it would be very irregular.
I suggest that you simply use a delaying counter loop, like
sub DelayAWhile(HowLongCount as long)
do until not cbool(HowLongCount)
HowLongCount = HowLongCount - 1
loop
end sub
or something similar. Then just toggle a pin in an endless loop with
the delay between them, like
sub Make600Hz()
do
putpin(pin600Hz, bxOutputHigh)
call DelayAWhile(HalfCycle600HzPeriodCount)
putpin(pin600Hz, bxOutputLow)
call DelayAWhile(HalfCycle600HzPeriodCount)
loop
end sub
This will still produce some irregularity due to the processor stealing
time for maintenance each RTC tick, so you will probably see the 600Hz
edges jitter. You can eliminate that jitter by preventing multitasking
by disabling Timer0, which stops the system tick. See
http://tech.groups.yahoo.com/group/basicx/message/21891 . Be careful to
heed the warning to place a pause at startup before you disable Timer0,
though, or you might not be able to regain control of the processor; you
must also do a physical Reset (drop pin 23 or power-cycle), since the
ATN pin won't be monitored.
On generating three-phase 100Hz, outputting a state list as you suggest
should be fine, each step triggered by the code above. To ensure that
all pins change state simultaneously, after you've set the pin direction
register you can output a byte to the port, like
register.DDRC = bx1111_0000 '4 pins as outputs
register.PortC = StateList(n)
See http://tech.groups.yahoo.com/group/basicx/message/22742 for driving
a 3-phase H-bridge for an implementation. Of course, you can also use
an external shift register to clock a single output bit through six
steps, each delayed by one-sixth cycle.
Tom
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 6 15:37:47 2010
Don Kinser points out that my ATN pin monitoring comment is not correct for current BX-24
machines, on which ATN just causes a hardware reset.
Still, I believe you should place a Delay() or Sleep() of a second or so at the start of your code, before you disable Timer0 to make sure the IDE can get control.
Tom
------------------------------------
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Still, I believe you should place a Delay() or Sleep() of a second or so at the start of your code, before you disable Timer0 to make sure the IDE can get control.
Tom
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 10 8:22:37 2010
Hi Tom,
1. My Pin25-27 works fine for outputing PWMs, but I can't get them work for Output Compare. I tried the code you've suggested in an earlier post. There's no fluctuation on the oscilloscope and the voltage reading is kept at 3.2V, below is the code I modified based on yours:
Option Explicit
Public Const GreenLEDO As Byte = 25
Public Sub Main()
Call Put20HzOnPin25()
End Sub
Sub Put20HzOnPin25()
Const T2mode As Byte = bx0001_1111 'flip 25, clear, 7200Hz
Register.TCCR2 = 0 'stop Timer2
Register.TCNT2 = 0
Register.OCR2 = 180 '20Hz>>>180, the relationship is linear
Register.TCCR2 = T2mode
End Sub
2. For the delaying counter loop idea you've suggested, I have concern over the delaying time consistency & the system overhead. I've tried similar thing yesterday, but instead of using counter loop as a more precise half-period delay, I used pulseout() to pulse a fixed duration to a dummy pin. Because the pulsing will halt the task for exactly the duration of pulsewidth, I assumed it to be precise. I did manage to generate a nice squarewave. However, my task needs me to vary the frequency discretely. I used 0.5ms (the half-period of 1000Hz) as the base, and I looped the pulseout(5ms) for 10 times trying to get 100Hz, and 100 times trying to get 10Hz. The result is not accurate, and I guess the reason lies with the system overhead (to my understanding, it's the time that spend on executing the commands like For Next etc etc). Is it really so?
3. My BX24 will need to carry out 3 other tasks (including one PID control, 3 ADC reading and some other Digital I/O work) while pausing out the 3 PWMs. Will it be too demanding for the controller?
Thanks!
Yuli
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
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1. My Pin25-27 works fine for outputing PWMs, but I can't get them work for Output Compare. I tried the code you've suggested in an earlier post. There's no fluctuation on the oscilloscope and the voltage reading is kept at 3.2V, below is the code I modified based on yours:
Option Explicit
Public Const GreenLEDO As Byte = 25
Public Sub Main()
Call Put20HzOnPin25()
End Sub
Sub Put20HzOnPin25()
Const T2mode As Byte = bx0001_1111 'flip 25, clear, 7200Hz
Register.TCCR2 = 0 'stop Timer2
Register.TCNT2 = 0
Register.OCR2 = 180 '20Hz>>>180, the relationship is linear
Register.TCCR2 = T2mode
End Sub
2. For the delaying counter loop idea you've suggested, I have concern over the delaying time consistency & the system overhead. I've tried similar thing yesterday, but instead of using counter loop as a more precise half-period delay, I used pulseout() to pulse a fixed duration to a dummy pin. Because the pulsing will halt the task for exactly the duration of pulsewidth, I assumed it to be precise. I did manage to generate a nice squarewave. However, my task needs me to vary the frequency discretely. I used 0.5ms (the half-period of 1000Hz) as the base, and I looped the pulseout(5ms) for 10 times trying to get 100Hz, and 100 times trying to get 10Hz. The result is not accurate, and I guess the reason lies with the system overhead (to my understanding, it's the time that spend on executing the commands like For Next etc etc). Is it really so?
3. My BX24 will need to carry out 3 other tasks (including one PID control, 3 ADC reading and some other Digital I/O work) while pausing out the 3 PWMs. Will it be too demanding for the controller?
Thanks!
Yuli
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )
Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 10 13:26:22 2010
> ... I can't get them work for Output Compare. I tried the code you've
suggested in an earlier post.
I assume you mean OutputCapture. The code you cite doesn't use
OutputCapture, and OutputCapture only generates a signal on pin 27; it
uses Timer1. The code you cited uses Timer2 to produce a signal on pin
25; there is no apparent output because the pin needs to be initialized
as an output, either high or low. Add
call PutPin(25, 1)
before you call Put20HzOnPin25 and it should work.
> ... I have concern over the delaying time consistency & the system
overhead...
Any code execution will take some time, some of it unproductive. As I
recall, the minimum execution time for a line of BX-24 code is ~32uS.
The following, for example, executes in ~32uS:
call PutPin(25, 1) ' LED off (~32uS)
Any conditional loop will need some additional time to test and loop or
exit, so even a simple loop like
do
call PutPin(25, 1) ' LED off (~32uS)
loop until True
uses ~53uS. The loop test alone takes ~21uS. A scope will also show
~10uS jitter, due to the system tick.
This means that - unless the signal is generated entirely in hardware
like the processor's PWM facility - some irregularity in a
processor-generated signal is unavoidable without care; adding dummy
instructions to an execution path can minimize jitter, for example.
Still, the system tick will cause jitter unless it is sacrificed.
Disabling it will produce a clean jitter-free signal, but at the cost of
multitasking and RTC functions. This code will loop at ~96uS, jitter-free:
sub Main()
call sleep(1.0)
register.TCCR0 = 0 ' system tick off
do
call PutPin(25,1) ' led off '~32uS
call PutPin(25,0) ' led off '~32uS
loop ' loop ~32uS
end sub
All this means that - if you need a clean, jitter-free signal, you
should generate it in hardware, either internal or external. If you use
code, especially multitasking code, to produce the signal it will be
irregular. You might be able to use a simpler processor dedicated to
the function, though, like a PIC.
> ... My BX24 will need to carry out 3 other tasks (including one PID
control, 3 ADC reading and some other Digital I/O work) while pausing
out the 3 PWMs. Will it be too demanding for the controller?
Since you already have difficulty with what you see from the machine, I
suspect yes.
Tom
------------------------------------
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suggested in an earlier post.
I assume you mean OutputCapture. The code you cite doesn't use
OutputCapture, and OutputCapture only generates a signal on pin 27; it
uses Timer1. The code you cited uses Timer2 to produce a signal on pin
25; there is no apparent output because the pin needs to be initialized
as an output, either high or low. Add
call PutPin(25, 1)
before you call Put20HzOnPin25 and it should work.
> ... I have concern over the delaying time consistency & the system
overhead...
Any code execution will take some time, some of it unproductive. As I
recall, the minimum execution time for a line of BX-24 code is ~32uS.
The following, for example, executes in ~32uS:
call PutPin(25, 1) ' LED off (~32uS)
Any conditional loop will need some additional time to test and loop or
exit, so even a simple loop like
do
call PutPin(25, 1) ' LED off (~32uS)
loop until True
uses ~53uS. The loop test alone takes ~21uS. A scope will also show
~10uS jitter, due to the system tick.
This means that - unless the signal is generated entirely in hardware
like the processor's PWM facility - some irregularity in a
processor-generated signal is unavoidable without care; adding dummy
instructions to an execution path can minimize jitter, for example.
Still, the system tick will cause jitter unless it is sacrificed.
Disabling it will produce a clean jitter-free signal, but at the cost of
multitasking and RTC functions. This code will loop at ~96uS, jitter-free:
sub Main()
call sleep(1.0)
register.TCCR0 = 0 ' system tick off
do
call PutPin(25,1) ' led off '~32uS
call PutPin(25,0) ' led off '~32uS
loop ' loop ~32uS
end sub
All this means that - if you need a clean, jitter-free signal, you
should generate it in hardware, either internal or external. If you use
code, especially multitasking code, to produce the signal it will be
irregular. You might be able to use a simpler processor dedicated to
the function, though, like a PIC.
> ... My BX24 will need to carry out 3 other tasks (including one PID
control, 3 ADC reading and some other Digital I/O work) while pausing
out the 3 PWMs. Will it be too demanding for the controller?
Since you already have difficulty with what you see from the machine, I
suspect yes.
Tom
------------------------------------
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Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 10 15:25:15 2010
> ... 3. My BX24 will need to carry out 3 other tasks (including one
PID control, 3 ADC reading and some other Digital I/O work) while
pausing out the 3 PWMs. Will it be too demanding for the controller?
On reconsideration - if you do not also need to produce the 100Hz three
phase you mentioned earlier, just the three PWMs - you should be able
to do what you list above on a BX-24. If you mix functions like PWM,
PulseOut and OutputCapture, though, you'll run into trouble since they
all use the same hardware timer and usually cannot coexist.
Tom
------------------------------------
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PID control, 3 ADC reading and some other Digital I/O work) while
pausing out the 3 PWMs. Will it be too demanding for the controller?
On reconsideration - if you do not also need to produce the 100Hz three
phase you mentioned earlier, just the three PWMs - you should be able
to do what you list above on a BX-24. If you mix functions like PWM,
PulseOut and OutputCapture, though, you'll run into trouble since they
all use the same hardware timer and usually cannot coexist.
Tom
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 17 3:21:34 2010
Hi Tom,
Thanks so much, after initialized the pin25 as Output pin for OutputCapture and it works very well now. :-) However I can't get the pin26 and pin27 work as OutputCapture, though I configured and initialized them in the similar way. Could you help me look at the new codes?
******************************************************************
Option Explicit
Public Const OpCmp1 As Byte = 25
Public Const OpCmp2 As Byte = 26
Public Const OpCmp3 As Byte = 27
Public Const T2mode As Byte = bx0001_1111 'flip 25, clear, 7200Hz
Public Const T1Amode As Byte = bx0101_0000
Public Const T1Bmode As Byte = bx0000_1111
Public Sub Main()
Call PutPin(Enable1,1)
Call PutPin(Enable2,0)
Call InitializeSqrWv()
Call SqrWvOnPin25(45)
Call SqrWvOnPin26(180)
Call SqrWvOnPin27(180)
End sub
Sub InitializeSqrWv()
' Register.TCCR2 = 0 'stop Timer2 (however I noticed that these initializations are not affecting the results, so I deactivated them)
' Register.TCNT2 = 0
' Register.OCR2 = 0
Register.TCCR2 = T2mode
' Register.TCCR1A = 0 'stop Timer1 and initialize the Timer1 value
' Register.TCCR1B = 0
' Register.TCNT1H = 0
' Register.TCNT1L = 0
' Register.OCR1AH = 0
' Register.OCR1BH = 0
' Register.OCR1AL = 0
' Register.OCR1BL = 0
Register.TCCR1A = T1Amode
Register.TCCR1B = T1Bmode
Call PutPin(OpCmp1,0) ' either output 0 or 1 will set the pin as output
Call PutPin(OpCmp2,0)
Call PutPin(OpCmp3,0)
End Sub
Sub SqrWvOnPin25(ByVal Freq As Byte)
Register.OCR2 = Freq '20Hz = Freq is 180, the relationship is inversely linear
End Sub
Sub SqrWvOnPin26(ByVal Freq As Byte)
Register.OCR1AL = Freq
End Sub
Sub SqrWvOnPin27(ByVal Freq As Byte)
Register.OCR1BL = Freq
End Sub
**********************************************************************
------------------------------------
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Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 17 13:39:13 2010
Here is a three-PWM demo that drives a three-color LED. Perhaps you can
find your errors by comparing your code to this code.
Tom
' Drive three-color LED
' GTBecker 2007-06-17
const pinPWMRed as byte = 25 ' Timer2 PWM
const pinPWMGreen as byte = 26 ' Timer1A PWM
const pinPWMBlue as byte = 27 ' Timer1B PWM
const pinControlRed as byte = 13 ' analog control inputs
const pinControlGreen as byte = 14
const pinControlBlue as byte = 15
Public Sub InitializePWMs()
Call PutPin(pinPWMRed, bxOutputHigh) ' init PWM pins
Call PutPin(pinPWMGreen, bxOutputHigh)
Call PutPin(pinPWMBlue, bxOutputHigh)
register.TCCR2 = bx0111_0001 ' Timer2 8-bit PWM, Clk/1024
register.OCR2 = 0 ' Clear duty cycle
Register.TCCR1A = bx1111_0001 ' Timer1 8-bit PWM
Register.TCCR1B = bx0000_0001 ' Clk/1024
Register.OCR1AH = 0 ' Clear duty cycles
Register.OCR1AL = 0
Register.OCR1BH = 0
Register.OCR1BL = 0
End Sub
Public Sub SetPWMs(ByVal PWMA As Byte, ByVal PWMB As byte, ByVal PWMC As
Byte)
'sets 8-bit PWMs
Register.OCR2 = PWMA
Register.OCR1AH = 0
Register.OCR1AL = PWMB
Register.OCR1BH = 0
Register.OCR1BL = PWMC
End Sub
Sub Main()
dim r as single, g as single, b as single, x as single
call sleep(0.5)
call InitializePWMs
do 'endless
r = csng(GetADC(pinControlRed)) / 4.0 ' ADC is 10-bit, PWM is
8-bit
g = csng(GetADC(pinControlGreen)) / 4.0
b = csng(GetADC(pinControlBlue)) / 4.0
'normalize to brightest color
x = r
if g > x then
x = g
end if
if b > x then
x = b
end if
x = x / 255.0 'normalize to 255
call SetPWMs(cbyte(g / x), cbyte(b / x), cbyte(r / x))
debug.print fmt(r / x, 0) &" "& fmt(g / x, 0) &" "& fmt(b / x, 0)
loop 'endless
end sub
------------------------------------
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find your errors by comparing your code to this code.
Tom
' Drive three-color LED
' GTBecker 2007-06-17
const pinPWMRed as byte = 25 ' Timer2 PWM
const pinPWMGreen as byte = 26 ' Timer1A PWM
const pinPWMBlue as byte = 27 ' Timer1B PWM
const pinControlRed as byte = 13 ' analog control inputs
const pinControlGreen as byte = 14
const pinControlBlue as byte = 15
Public Sub InitializePWMs()
Call PutPin(pinPWMRed, bxOutputHigh) ' init PWM pins
Call PutPin(pinPWMGreen, bxOutputHigh)
Call PutPin(pinPWMBlue, bxOutputHigh)
register.TCCR2 = bx0111_0001 ' Timer2 8-bit PWM, Clk/1024
register.OCR2 = 0 ' Clear duty cycle
Register.TCCR1A = bx1111_0001 ' Timer1 8-bit PWM
Register.TCCR1B = bx0000_0001 ' Clk/1024
Register.OCR1AH = 0 ' Clear duty cycles
Register.OCR1AL = 0
Register.OCR1BH = 0
Register.OCR1BL = 0
End Sub
Public Sub SetPWMs(ByVal PWMA As Byte, ByVal PWMB As byte, ByVal PWMC As
Byte)
'sets 8-bit PWMs
Register.OCR2 = PWMA
Register.OCR1AH = 0
Register.OCR1AL = PWMB
Register.OCR1BH = 0
Register.OCR1BL = PWMC
End Sub
Sub Main()
dim r as single, g as single, b as single, x as single
call sleep(0.5)
call InitializePWMs
do 'endless
r = csng(GetADC(pinControlRed)) / 4.0 ' ADC is 10-bit, PWM is
8-bit
g = csng(GetADC(pinControlGreen)) / 4.0
b = csng(GetADC(pinControlBlue)) / 4.0
'normalize to brightest color
x = r
if g > x then
x = g
end if
if b > x then
x = b
end if
x = x / 255.0 'normalize to 255
call SetPWMs(cbyte(g / x), cbyte(b / x), cbyte(r / x))
debug.print fmt(r / x, 0) &" "& fmt(g / x, 0) &" "& fmt(b / x, 0)
loop 'endless
end sub
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 18 9:21:19 2010
Hi Tom,
I myself have a code for driving 3 PWM simultaneously and it's working well. I compared your PWM codes with mine but cannot get any hint why my codes for 3 OutputCapture is not working. Could you help me look at my codes or suggest me any codes that is to use 3 OutputCapture together?
Sorry to bother you again but I can't find anyone else around me who knows BX24 deep down in assembly level.
------------------------------------
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I myself have a code for driving 3 PWM simultaneously and it's working well. I compared your PWM codes with mine but cannot get any hint why my codes for 3 OutputCapture is not working. Could you help me look at my codes or suggest me any codes that is to use 3 OutputCapture together?
Sorry to bother you again but I can't find anyone else around me who knows BX24 deep down in assembly level.
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 18 12:01:30 2010
Did I miss your OutputCapture code? You provided PWM code that didn't work on pins 26 and
27 when I compiled it, but I see no OutputCapture, Yuli.
Tom
------------------------------------
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Tom
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 18 13:17:32 2010
Hi Tom,
Just to confirm that this is the code that both of us are talking about, am I not mistaken?
I think this is an output capture rather than PWM, I use it to generate squarewaves with fixed 50% duty cycle but variable frequency.
Regards
Yuli
******************************************************************
Option Explicit
Public Const OpCmp1 As Byte = 25
Public Const OpCmp2 As Byte = 26
Public Const OpCmp3 As Byte = 27
Public Const T2mode As Byte = bx0001_1111 'flip 25, clear, 7200Hz
Public Const T1Amode As Byte = bx0101_0000
Public Const T1Bmode As Byte = bx0000_1111
Public Sub Main()
Call PutPin(Enable1,1)
Call PutPin(Enable2,0)
Call InitializeSqrWv()
Call SqrWvOnPin25(45)
Call SqrWvOnPin26(180)
Call SqrWvOnPin27(180)
End sub
Sub InitializeSqrWv()
' Register.TCCR2 = 0 'stop Timer2 (however I noticed that these initializations
are not affecting the results, so I deactivated them)
' Register.TCNT2 = 0
' Register.OCR2 = 0
Register.TCCR2 = T2mode
' Register.TCCR1A = 0 'stop Timer1 and initialize the Timer1 value
' Register.TCCR1B = 0
' Register.TCNT1H = 0
' Register.TCNT1L = 0
' Register.OCR1AH = 0
' Register.OCR1BH = 0
' Register.OCR1AL = 0
' Register.OCR1BL = 0
Register.TCCR1A = T1Amode
Register.TCCR1B = T1Bmode
Call PutPin(OpCmp1,0) ' either output 0 or 1 will set the pin as output
Call PutPin(OpCmp2,0)
Call PutPin(OpCmp3,0)
End Sub
Sub SqrWvOnPin25(ByVal Freq As Byte)
Register.OCR2 = Freq '20Hz = Freq is 180, the relationship is inversely linear
End Sub
Sub SqrWvOnPin26(ByVal Freq As Byte)
Register.OCR1AL = Freq
End Sub
Sub SqrWvOnPin27(ByVal Freq As Byte)
Register.OCR1BL = Freq
End Sub
**********************************************************************
------------------------------------
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Just to confirm that this is the code that both of us are talking about, am I not mistaken?
I think this is an output capture rather than PWM, I use it to generate squarewaves with fixed 50% duty cycle but variable frequency.
Regards
Yuli
******************************************************************
Option Explicit
Public Const OpCmp1 As Byte = 25
Public Const OpCmp2 As Byte = 26
Public Const OpCmp3 As Byte = 27
Public Const T2mode As Byte = bx0001_1111 'flip 25, clear, 7200Hz
Public Const T1Amode As Byte = bx0101_0000
Public Const T1Bmode As Byte = bx0000_1111
Public Sub Main()
Call PutPin(Enable1,1)
Call PutPin(Enable2,0)
Call InitializeSqrWv()
Call SqrWvOnPin25(45)
Call SqrWvOnPin26(180)
Call SqrWvOnPin27(180)
End sub
Sub InitializeSqrWv()
' Register.TCCR2 = 0 'stop Timer2 (however I noticed that these initializations
are not affecting the results, so I deactivated them)
' Register.TCNT2 = 0
' Register.OCR2 = 0
Register.TCCR2 = T2mode
' Register.TCCR1A = 0 'stop Timer1 and initialize the Timer1 value
' Register.TCCR1B = 0
' Register.TCNT1H = 0
' Register.TCNT1L = 0
' Register.OCR1AH = 0
' Register.OCR1BH = 0
' Register.OCR1AL = 0
' Register.OCR1BL = 0
Register.TCCR1A = T1Amode
Register.TCCR1B = T1Bmode
Call PutPin(OpCmp1,0) ' either output 0 or 1 will set the pin as output
Call PutPin(OpCmp2,0)
Call PutPin(OpCmp3,0)
End Sub
Sub SqrWvOnPin25(ByVal Freq As Byte)
Register.OCR2 = Freq '20Hz = Freq is 180, the relationship is inversely linear
End Sub
Sub SqrWvOnPin26(ByVal Freq As Byte)
Register.OCR1AL = Freq
End Sub
Sub SqrWvOnPin27(ByVal Freq As Byte)
Register.OCR1BL = Freq
End Sub
**********************************************************************
------------------------------------
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Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 18 13:26:39 2010
> ... I think this is an output capture rather than PWM...
No, OutputCapture uses the OutputCapture procedure, which is given an
array of values that describe a finite series of output pulses to
generate. There is no OutputCapture in your posted code.
The code you posted attempts to generate three PWM streams, it appears;
your code only succeeds on pin 25. The code I posted works on all three
pins.
Tom
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
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No, OutputCapture uses the OutputCapture procedure, which is given an
array of values that describe a finite series of output pulses to
generate. There is no OutputCapture in your posted code.
The code you posted attempts to generate three PWM streams, it appears;
your code only succeeds on pin 25. The code I posted works on all three
pins.
Tom
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 19 13:48:16 2010
Hi Tom,
My fault, I've mixed up the concepts of OutputCapture and OutputCompare. When I learned assembly programming using Motorola HC11, I learned to use OutputCompare to generate fixed 50% duty-cycle square waves with varied frequencies, that's why I call this function Output Compare, and I use this name subsequently to differentiate it from PWM, which is of fixed frequency but varied duty-cycle. Anyway, my previous code aims to generate 50% dutycycle varied frequency square waves, and the codes I've posted is actually edited from your codes posted on an earlier thread, which allows Pin25 to carry out this function. I followed the 8535's manual to configure Pin26 and Pin27 in the similar way but cannot get it to work as Pin25. The codes you've posted just now doesn't suits my application as it is to generate varied duty-cycle but fixed frequency PWM squarewaves.
I've considered using OutputCapture as well, but this function requires me to define an array of pulsewidthes which must be a finite set of numbers. So I still need to use loop in order to generate a continuous pulse, which is not precise.
------------------------------------
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )
My fault, I've mixed up the concepts of OutputCapture and OutputCompare. When I learned assembly programming using Motorola HC11, I learned to use OutputCompare to generate fixed 50% duty-cycle square waves with varied frequencies, that's why I call this function Output Compare, and I use this name subsequently to differentiate it from PWM, which is of fixed frequency but varied duty-cycle. Anyway, my previous code aims to generate 50% dutycycle varied frequency square waves, and the codes I've posted is actually edited from your codes posted on an earlier thread, which allows Pin25 to carry out this function. I followed the 8535's manual to configure Pin26 and Pin27 in the similar way but cannot get it to work as Pin25. The codes you've posted just now doesn't suits my application as it is to generate varied duty-cycle but fixed frequency PWM squarewaves.
I've considered using OutputCapture as well, but this function requires me to define an array of pulsewidthes which must be a finite set of numbers. So I still need to use loop in order to generate a continuous pulse, which is not precise.
------------------------------------
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )
Re: Re: can we have more than 2 PWM ports on BX24P? - rosa...@aol.com - Feb 19 14:26:41 2010
Hi,
I have been following your problem but since I never had to use PWM I can not make any suggestions.. My question is does the continues pulse are fixed or you have to change the frequency. Are they are square? What are trying to do with the pulses?
Regards,
rosarite.
-----Original Message-----
From: Yuli
To: b...@yahoogroups.com
Sent: Fri, Feb 19, 2010 12:45 pm
Subject: [BasicX] Re: can we have more than 2 PWM ports on BX24P?
Hi Tom,
My fault, I've mixed up the concepts of OutputCapture and OutputCompare. When I learned assembly programming using Motorola HC11, I learned to use OutputCompare to generate fixed 50% duty-cycle square waves with varied frequencies, that's why I call this function Output Compare, and I use this name subsequently to differentiate it from PWM, which is of fixed frequency but varied duty-cycle. Anyway, my previous code aims to generate 50% dutycycle varied frequency square waves, and the codes I've posted is actually edited from your codes posted on an earlier thread, which allows Pin25 to carry out this function. I followed the 8535's manual to configure Pin26 and Pin27 in the similar way but cannot get it to work as Pin25. The codes you've posted just now doesn't suits my application as it is to generate varied duty-cycle but fixed frequency PWM squarewaves.
I've considered using OutputCapture as well, but this function requires me to define an array of pulsewidthes which must be a finite set of numbers. So I still need to use loop in order to generate a continuous pulse, which is not precise.
[Non-text portions of this message have been removed]
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 19 16:26:59 2010
Hi Rosarite,
I'm trying to generate continuous squarewave with an adjustable frequency. These square way pulses will be use for providing step signal to drive stepper motor. The normal way of using delay to generate squarewave can only be used for low frequency drives, I need to utilize the hardware timer to generate pulses if I want higher frequencies. That's why I was asking.
Yuli
------------------------------------
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I'm trying to generate continuous squarewave with an adjustable frequency. These square way pulses will be use for providing step signal to drive stepper motor. The normal way of using delay to generate squarewave can only be used for low frequency drives, I need to utilize the hardware timer to generate pulses if I want higher frequencies. That's why I was asking.
Yuli
------------------------------------
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Re: Re: can we have more than 2 PWM ports on BX24P? - rosa...@aol.com - Feb 19 17:13:29 2010
Hi,
Did you ever considered a stepper motor driver board that allow you to do it with two signals? There are some store that have it and the only you need is one direction control signal and one that provide the step pulses.
Regards,
rosarite
-----Original Message-----
From: Yuli
To: b...@yahoogroups.com
Sent: Fri, Feb 19, 2010 3:24 pm
Subject: [BasicX] Re: can we have more than 2 PWM ports on BX24P?
Hi Rosarite,
I'm trying to generate continuous squarewave with an adjustable frequency. These square way pulses will be use for providing step signal to drive stepper motor. The normal way of using delay to generate squarewave can only be used for low frequency drives, I need to utilize the hardware timer to generate pulses if I want higher frequencies. That's why I was asking.
Yuli
[Non-text portions of this message have been removed]
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
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Re: Re: can we have more than 2 PWM ports on BX24P? - Tom Becker - Feb 19 20:36:23 2010
> ... 50% duty cycle varied frequency...
OK, either I missed that or it was not clearly expressed. There is a
confusing matter of terminology: BasicX uses OutputCompare for it's
finite pulse stream generation procedure; Atmel uses Output Compare to
describe a register in the Timer mechanisms, perhaps similar to your
HC11 experience. If the timer mode is appropriate, the value in the
OCR1A or OCR1B register will define how often the output pin is toggled,
producing a variable-frequency 50% output.
If I now understand what you want to do, you want CTC mode, timer mode 4
(http://www.atmel.com/dyn/resources/prod_documents/doc2502.pdf). Try this:
sub Init()
call putpin(25, 0) ' init pins out
call putpin(26, 0)
call putpin(27, 0)
Register.TCCR2 = bx0001_1110 ' toggle 25, clear count on match, 1/256
Register.TCCR1A = bx0101_0000 ' toggle 26 and 27, clear count on
match
Register.TCCR1B = bx0000_1100 ' 1/256
end sub
sub Main()
dim Count as integer
call Init
do
for Count = 255 to 0 step -1
Register.OCR1AH = cbyte(Count \ 256)
Register.OCR1AL = cbyte(Count mod 265)
Register.OCR1BH = cbyte(Count \ 256)
Register.OCR1BL = cbyte(Count mod 256)
Register.OCR2 = cbyte(Count)
call sleep(0.05)
next
loop
end sub
Tom
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )
OK, either I missed that or it was not clearly expressed. There is a
confusing matter of terminology: BasicX uses OutputCompare for it's
finite pulse stream generation procedure; Atmel uses Output Compare to
describe a register in the Timer mechanisms, perhaps similar to your
HC11 experience. If the timer mode is appropriate, the value in the
OCR1A or OCR1B register will define how often the output pin is toggled,
producing a variable-frequency 50% output.
If I now understand what you want to do, you want CTC mode, timer mode 4
(http://www.atmel.com/dyn/resources/prod_documents/doc2502.pdf). Try this:
sub Init()
call putpin(25, 0) ' init pins out
call putpin(26, 0)
call putpin(27, 0)
Register.TCCR2 = bx0001_1110 ' toggle 25, clear count on match, 1/256
Register.TCCR1A = bx0101_0000 ' toggle 26 and 27, clear count on
match
Register.TCCR1B = bx0000_1100 ' 1/256
end sub
sub Main()
dim Count as integer
call Init
do
for Count = 255 to 0 step -1
Register.OCR1AH = cbyte(Count \ 256)
Register.OCR1AL = cbyte(Count mod 265)
Register.OCR1BH = cbyte(Count \ 256)
Register.OCR1BL = cbyte(Count mod 256)
Register.OCR2 = cbyte(Count)
call sleep(0.05)
next
loop
end sub
Tom
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 20 4:09:36 2010
Hi Rosarite,
Yes I'm actually using stepper motor drivers A4983, so I just need 1 squarewave for each stepper. But I need to drive 3 steppers seperately, so I need generate 3 different squarewaves.
Yuli
------------------------------------
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Yes I'm actually using stepper motor drivers A4983, so I just need 1 squarewave for each stepper. But I need to drive 3 steppers seperately, so I need generate 3 different squarewaves.
Yuli
------------------------------------
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Re: can we have more than 2 PWM ports on BX24P? - Yuli - Feb 20 10:09:40 2010
Hi Tom,
I've found the problem with my codes. The timer1 clock select(last 3 digits of register TCCR1B) was set to "111", which means "PCK2/1024", i.e. 7200Hz in timer2 clcok select. But in timer1 clock select "111" corresponds to "External Pin T1, rising edge" instead, which definitely is not what I want though I don't know what it is. haha... Anyway, thanks a lot for the reference code and I believe my codes will work fine after modifying the Register TCCR1B!
Yuli
------------------------------------
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I've found the problem with my codes. The timer1 clock select(last 3 digits of register TCCR1B) was set to "111", which means "PCK2/1024", i.e. 7200Hz in timer2 clcok select. But in timer1 clock select "111" corresponds to "External Pin T1, rising edge" instead, which definitely is not what I want though I don't know what it is. haha... Anyway, thanks a lot for the reference code and I believe my codes will work fine after modifying the Register TCCR1B!
Yuli
------------------------------------
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