Hello All,
After several months of developing with the MCB2130 eval board I
finally got my first prototype hardware. I am pretty excited, but I
have a couple issues.
My first big issue is the SPI output signals. I am communicating
with two other devices over an SPI bus where the LPC is the master.
The signals coming out of the LPC are correct, except the peak
voltage of the MCLK and MOSI are about 1Volt!
Orignally, I had buffers on all the SPI lines, but due to cost
pressure I had to take them out. I read that the max output current
for the LPC pins is like 4mA.
Question: Are the LPC2131 outputs really that wimpy? Has anybody
else had this problem? Did you just add buffers?
Second issue is with the JTAG interface.
The ULINK worked flawless with the MCB2130 eval board running with
12MHz crystal. But my hardware uses a 12.288MHz crystal. I have
changed the crystal and PLL settings in startup.s and the debugger
but, I is still very unreliable. I have gotten it to work about 3
times out of 50? Mostly, I download my code using the Philips Flash
Utility over the serial port.
Also, I worked thru all the suggestions in the Keil knowledgebase
regarding "JTAG Communication Failure" with the ULINK. None of
these things fixed it. I suspect it has something to do with the
clock settings.
Does anybody know of any other tricks or secret clock settings in
uVision3 or startup.s?
Thanks,
Dave Butler
LPC2131 SPI output drive and ULINK JTAG issues
Started by ●July 20, 2005
Reply by ●July 20, 20052005-07-20
I had a board with JTAG problems. Started 1 in 10 or so. Good enough
to make me think it was in the startup code somewhere. I pulled hair -
looking at startup, swapping JTAG debuggers, etc.
I finally traced this to a missing bulk bypass cap in the V1.8 supply.
The supply had high frequency oscillations on it. Adding a cap made it
super reliable.
_____
From: lpc2000@lpc2... [mailto:lpc2000@lpc2...] On Behalf
Of drb5599
Sent: Wednesday, July 20, 2005 6:48 AM
To: lpc2000@lpc2...
Subject: [lpc2000] LPC2131 SPI output drive and ULINK JTAG issues
Hello All,
After several months of developing with the MCB2130 eval board I
finally got my first prototype hardware. I am pretty excited, but I
have a couple issues.
My first big issue is the SPI output signals. I am communicating
with two other devices over an SPI bus where the LPC is the master.
The signals coming out of the LPC are correct, except the peak
voltage of the MCLK and MOSI are about 1Volt!
Orignally, I had buffers on all the SPI lines, but due to cost
pressure I had to take them out. I read that the max output current
for the LPC pins is like 4mA.
Question: Are the LPC2131 outputs really that wimpy? Has anybody
else had this problem? Did you just add buffers?
Second issue is with the JTAG interface.
The ULINK worked flawless with the MCB2130 eval board running with
12MHz crystal. But my hardware uses a 12.288MHz crystal. I have
changed the crystal and PLL settings in startup.s and the debugger
but, I is still very unreliable. I have gotten it to work about 3
times out of 50? Mostly, I download my code using the Philips Flash
Utility over the serial port.
Also, I worked thru all the suggestions in the Keil knowledgebase
regarding "JTAG Communication Failure" with the ULINK. None of
these things fixed it. I suspect it has something to do with the
clock settings.
Does anybody know of any other tricks or secret clock settings in
uVision3 or startup.s?
Thanks,
Dave Butler _____
> .
_____
to make me think it was in the startup code somewhere. I pulled hair -
looking at startup, swapping JTAG debuggers, etc.
I finally traced this to a missing bulk bypass cap in the V1.8 supply.
The supply had high frequency oscillations on it. Adding a cap made it
super reliable.
_____
From: lpc2000@lpc2... [mailto:lpc2000@lpc2...] On Behalf
Of drb5599
Sent: Wednesday, July 20, 2005 6:48 AM
To: lpc2000@lpc2...
Subject: [lpc2000] LPC2131 SPI output drive and ULINK JTAG issues
Hello All,
After several months of developing with the MCB2130 eval board I
finally got my first prototype hardware. I am pretty excited, but I
have a couple issues.
My first big issue is the SPI output signals. I am communicating
with two other devices over an SPI bus where the LPC is the master.
The signals coming out of the LPC are correct, except the peak
voltage of the MCLK and MOSI are about 1Volt!
Orignally, I had buffers on all the SPI lines, but due to cost
pressure I had to take them out. I read that the max output current
for the LPC pins is like 4mA.
Question: Are the LPC2131 outputs really that wimpy? Has anybody
else had this problem? Did you just add buffers?
Second issue is with the JTAG interface.
The ULINK worked flawless with the MCB2130 eval board running with
12MHz crystal. But my hardware uses a 12.288MHz crystal. I have
changed the crystal and PLL settings in startup.s and the debugger
but, I is still very unreliable. I have gotten it to work about 3
times out of 50? Mostly, I download my code using the Philips Flash
Utility over the serial port.
Also, I worked thru all the suggestions in the Keil knowledgebase
regarding "JTAG Communication Failure" with the ULINK. None of
these things fixed it. I suspect it has something to do with the
clock settings.
Does anybody know of any other tricks or secret clock settings in
uVision3 or startup.s?
Thanks,
Dave Butler _____
> .
_____
Reply by ●August 11, 20052005-08-11
All,
Problem is fixed. JTAG works on my proto hardware.
The JTAG (P1.36-26) pins were configured for GPIO instead of debug.
In the PINSEL2 register I had to set bit #2. That did it.
All is well now, but I still do not understand why the JTAG worked
on the Keil MCB2130 eval board?? I was not setting PINSEL2 bit 2 in
my code. Does the LPC2138 not need to have this bit set, where the
LPC2131 does?
Anyone using the Keil MCB2130, please take note of this issue if you
plan on using the JTAG interface on your own hardware.
Thanks for your help and suggestions.
Dave Butler --- In lpc2000@lpc2..., "Dan Beadle" <dan.beadle@i...> wrote:
> I had a board with JTAG problems. Started 1 in 10 or so. Good
enough
> to make me think it was in the startup code somewhere. I pulled
hair -
> looking at startup, swapping JTAG debuggers, etc. >
> I finally traced this to a missing bulk bypass cap in the V1.8
supply.
> The supply had high frequency oscillations on it. Adding a cap
made it
> super reliable. >
> _____
>
> From: lpc2000@lpc2... [mailto:lpc2000@lpc2...] On
Behalf
> Of drb5599
> Sent: Wednesday, July 20, 2005 6:48 AM
> To: lpc2000@lpc2...
> Subject: [lpc2000] LPC2131 SPI output drive and ULINK JTAG issues >
> Hello All,
> After several months of developing with the MCB2130 eval board I
> finally got my first prototype hardware. I am pretty excited, but
I
> have a couple issues.
>
> My first big issue is the SPI output signals. I am communicating
> with two other devices over an SPI bus where the LPC is the
master.
> The signals coming out of the LPC are correct, except the peak
> voltage of the MCLK and MOSI are about 1Volt!
> Orignally, I had buffers on all the SPI lines, but due to cost
> pressure I had to take them out. I read that the max output
current
> for the LPC pins is like 4mA.
>
> Question: Are the LPC2131 outputs really that wimpy? Has anybody
> else had this problem? Did you just add buffers?
>
> Second issue is with the JTAG interface.
> The ULINK worked flawless with the MCB2130 eval board running with
> 12MHz crystal. But my hardware uses a 12.288MHz crystal. I have
> changed the crystal and PLL settings in startup.s and the debugger
> but, I is still very unreliable. I have gotten it to work about 3
> times out of 50? Mostly, I download my code using the Philips
Flash
> Utility over the serial port.
>
> Also, I worked thru all the suggestions in the Keil knowledgebase
> regarding "JTAG Communication Failure" with the ULINK. None of
> these things fixed it. I suspect it has something to do with the
> clock settings.
> Does anybody know of any other tricks or secret clock settings in
> uVision3 or startup.s?
>
> Thanks,
> Dave Butler > _____
>
> > . >
> _____ >
>
Problem is fixed. JTAG works on my proto hardware.
The JTAG (P1.36-26) pins were configured for GPIO instead of debug.
In the PINSEL2 register I had to set bit #2. That did it.
All is well now, but I still do not understand why the JTAG worked
on the Keil MCB2130 eval board?? I was not setting PINSEL2 bit 2 in
my code. Does the LPC2138 not need to have this bit set, where the
LPC2131 does?
Anyone using the Keil MCB2130, please take note of this issue if you
plan on using the JTAG interface on your own hardware.
Thanks for your help and suggestions.
Dave Butler --- In lpc2000@lpc2..., "Dan Beadle" <dan.beadle@i...> wrote:
> I had a board with JTAG problems. Started 1 in 10 or so. Good
enough
> to make me think it was in the startup code somewhere. I pulled
hair -
> looking at startup, swapping JTAG debuggers, etc. >
> I finally traced this to a missing bulk bypass cap in the V1.8
supply.
> The supply had high frequency oscillations on it. Adding a cap
made it
> super reliable. >
> _____
>
> From: lpc2000@lpc2... [mailto:lpc2000@lpc2...] On
Behalf
> Of drb5599
> Sent: Wednesday, July 20, 2005 6:48 AM
> To: lpc2000@lpc2...
> Subject: [lpc2000] LPC2131 SPI output drive and ULINK JTAG issues >
> Hello All,
> After several months of developing with the MCB2130 eval board I
> finally got my first prototype hardware. I am pretty excited, but
I
> have a couple issues.
>
> My first big issue is the SPI output signals. I am communicating
> with two other devices over an SPI bus where the LPC is the
master.
> The signals coming out of the LPC are correct, except the peak
> voltage of the MCLK and MOSI are about 1Volt!
> Orignally, I had buffers on all the SPI lines, but due to cost
> pressure I had to take them out. I read that the max output
current
> for the LPC pins is like 4mA.
>
> Question: Are the LPC2131 outputs really that wimpy? Has anybody
> else had this problem? Did you just add buffers?
>
> Second issue is with the JTAG interface.
> The ULINK worked flawless with the MCB2130 eval board running with
> 12MHz crystal. But my hardware uses a 12.288MHz crystal. I have
> changed the crystal and PLL settings in startup.s and the debugger
> but, I is still very unreliable. I have gotten it to work about 3
> times out of 50? Mostly, I download my code using the Philips
Flash
> Utility over the serial port.
>
> Also, I worked thru all the suggestions in the Keil knowledgebase
> regarding "JTAG Communication Failure" with the ULINK. None of
> these things fixed it. I suspect it has something to do with the
> clock settings.
> Does anybody know of any other tricks or secret clock settings in
> uVision3 or startup.s?
>
> Thanks,
> Dave Butler > _____
>
> > . >
> _____ >
>
