Reply by Jim Granville●September 27, 20062006-09-27
austinv@gmail.com wrote:
> I'm in a group designing a 3d positioning system for a foot for a class
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
This is rather short on specifics, like how many processors you expect
to use, and the task partitions ?.
For just PWM readout, (frequency?, Duty range ?) you can use 6 channels
of capture, and derive the edge times - you do not have to use 6 timers.
So, that allows some small 8 bit uC as well, eg the Silabs C8051F410
has a lot of usefull peripherals for the coal-face stuff for positioning.
-jg
Reply by Yuriy K.●September 25, 20062006-09-25
langwadt@ieee.org wrote:
>>> Freescale MAC7100, sixteen timers each 16 bit, lots of operating modes,
>>> such as:
>>> input pulsewidth measurement, input period measurement
>> And not available for general public... :(
>>
> Arrow have 115 mac7111 in stock,
> and you can order samples of several different
> parts from the family on the freescale site
> langwadt@ieee.org wrote:
> > Freescale MAC7100, sixteen timers each 16 bit, lots of operating modes,
> > such as:
> > input pulsewidth measurement, input period measurement
>
> And not available for general public... :(
>
huh?
Arrow have 115 mac7111 in stock, and you can order samples of several
different
parts from the family on the freescale site
-Lasse
Reply by Yuriy K.●September 25, 20062006-09-25
austinv@gmail.com wrote:
> I'm in a group designing a 3d positioning system for a foot for a class
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
MC9S12xxxx - 8+ counters
--
WBR, Yuriy.
"Resistance is futile"
Reply by Yuriy K.●September 25, 20062006-09-25
langwadt@ieee.org wrote:
> Freescale MAC7100, sixteen timers each 16 bit, lots of operating modes,
> such as:
> input pulsewidth measurement, input period measurement
Reply by Ulf Samuelsson●September 25, 20062006-09-25
<austinv@gmail.com> skrev i meddelandet
news:1159213524.624840.259860@b28g2000cwb.googlegroups.com...
> I'm in a group designing a 3d positioning system for a foot for a class
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
>
AT91SAM7A3 will get you USB, 16 ADC channels and 9 x 16 bit timers
--
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may not be shared by my employer Atmel Nordic AB
Reply by larwe●September 25, 20062006-09-25
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
Use the analog outputs, and a micro with multiple ADCs... how parallel
does it need to be? The MSP430 can automagically round-robin the
channels for you.
Reply by ●September 25, 20062006-09-25
aust...@gmail.com wrote:
> I'm in a group designing a 3d positioning system for a foot for a class
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
> In article <1159213524.624840.259860@b28g2000cwb.googlegroups.com>,
> austinv@gmail.com says...
> > I'm in a group designing a 3d positioning system for a foot for a class
> > project this semester. We're looking to base our device on some analog
> > devices accelerometers, and hopefully incorporate Bluetooth support
> > (but we may well just use USB to get the data off). The accelerometers
> > have 2-axs PWM output and we'll be using four; does anyone know of any
> > low cost chips with lots of counters, for the sake of getting all this
> > PWM data in parallel?
> >
> >
> Any of the Freescale parts with the Time Processing Unit (TPU) should
> handle that chore.
>
> Otherwise, if your data collection rates are low, it may be possible
> to use a digital multplexer to select one of the accelerometers,
> measure it for a while, then select the next, measure it for a
> while, etc. etc.
I think data rate is approx. 1 KHz and response time of seconds. I
would pick the solution below rather than above. You don't want it in
interrupt, since you would need a dedicated micro doing only this job.
>
> Another trick I've used for very slow monitoring of PWM sensors
> (one reading each minute or so) is to sample all the inputs
> at once on a regular basis (in an interrupt routine, perhaps).
> With each sample, you record whether the particular input
> bit is high or low. After a few thousand samples, you
> have an adequate statistical represention of the high and
> low times of the inputs. That worked fine for a set of
> greenhouse temperature sensors.
>
> Mark Borgerson
Reply by Mark Borgerson●September 25, 20062006-09-25
In article <1159213524.624840.259860@b28g2000cwb.googlegroups.com>,
austinv@gmail.com says...
> I'm in a group designing a 3d positioning system for a foot for a class
> project this semester. We're looking to base our device on some analog
> devices accelerometers, and hopefully incorporate Bluetooth support
> (but we may well just use USB to get the data off). The accelerometers
> have 2-axs PWM output and we'll be using four; does anyone know of any
> low cost chips with lots of counters, for the sake of getting all this
> PWM data in parallel?
>
>
Any of the Freescale parts with the Time Processing Unit (TPU) should
handle that chore.
Otherwise, if your data collection rates are low, it may be possible
to use a digital multplexer to select one of the accelerometers,
measure it for a while, then select the next, measure it for a
while, etc. etc.
Another trick I've used for very slow monitoring of PWM sensors
(one reading each minute or so) is to sample all the inputs
at once on a regular basis (in an interrupt routine, perhaps).
With each sample, you record whether the particular input
bit is high or low. After a few thousand samples, you
have an adequate statistical represention of the high and
low times of the inputs. That worked fine for a set of
greenhouse temperature sensors.
Mark Borgerson