[PD] Pduino: change read speed

Roman Haefeli reduzierer at yahoo.de
Sat Jan 13 11:14:28 CET 2007

On Sat, 2007-01-13 at 01:17 -0500, Martin Peach wrote:
> Roman Haefeli wrote:
> > hello
> >
> > i recently ordered two arduino boards and now i try my first steps with
> > it. i downloaded Pduino-0.2 and uploaded the firmware to the chip. i
> > encountered a little, but sometimes annoying problem, when using the
> > board with [arduino]-object. when i enable one or more analog inputs,
> > the arduino sends so much data, that data sent from computer to arduino
> > gets delayed, sometimes up to 10 seconds. this makes it impossible for
> > me to use the outputs, while using the analog ins at the same time. i
> > use the [arduino]-object as it is (with the hardcoded baudrate of
> > 115200) and i connect the arduino-board directly to one of my laptop's
> > usb-ports. 
> > i counted the messages i receive from the the analog input, when i
> > enable it:
> > 1 analog input enabled:  ~960 values/s 
> > 2 analog inputs enabled: ~480 values/s per input
> > 3 analog inputs enabled: ~320 values/s per input 
> > (and so on)
> >
> > would it be easy to change the code of the firmware, so that it sends
> > the values of each analog input with a fixed rate (e.g. 100 Hz)?
> >
> >   
> You could always run at a baud rate like 1200, so the arduino is not 
> able to send more than 120 bytes per second.

the problem i have, is not that i don't want so much data, but that the
analogIns eat whole bandwidth, so that i get jitter on the digitalOuts.
setting another baud rate doesn't seem to solve this problem, since the
analogIns send with lower rate then, but still eat whole available
bandwidth. maybe i am totally wrong, but my assumption is, that when the
analogIns don't send so fast, that they fill the bandwidth, there would
be less jitter on the digitalOuts. when using digitalOuts without the
analogIns enabled, i don't have noticable jitter at all. that is why i
thought, limiting the speed of the analogIns would help. 


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