[PD] pduino and FSRs

nick burge tectp at telefonica.net
Sat Apr 12 15:59:31 CEST 2008


OK this is getting interesting. 
I have got the FSRs set up again on my breadboard so I can experiment a bit.
I've tried different baud rates and get the same result...that is to say a
crash in PD. 
The FSRs connect to Phidget voltage dividers as recommended by the suppliers
and from the  voltage dividers we have 3 wires: analog in, 5v and ground.
Now if I swap the wires they call "analog in" with the 5v wire on the
breadboard and connect again to Pduino I can enable all the analog inputs in
the Arduino object and NO CRASH....
I am no expert in electronics, but I'm sure someone can give me an
explanation as to what is going on. 
Looking at the manual for the Phidget voltage dividers I see that in the
proprietry software designed for use with the phidget microprocessor there
is a setting you have to select: namely "Ratiometric" when using these
voltage dividers. Could that have anything to do with it?
 
Nick.

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 12 April 2008 00:41
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs



I use 6 analog inputs all of the time on Mac and Linux. I've never used
19200 tho. Try using [comport] alone to eliminate anything in [arduino].
Maybe there is a bug in comport on vista?

.hc

On Apr 11, 2008, at 3:17 PM, nick burge wrote:


Thank you Hans, am I being unrealistic in trying to have six analog inputs
active all at once? I know you said that was a lot of data, but I run a
fairly powerful laptop with a dual core Centrino processor, and Windows task
manager reports only a modest demand on the cpu of around 30% when I have
the patch running and all inputs active, so it seems to be an error in
timing or syncronisation rather than simply overstressing the system that
causes this....I've taken the patch right down to the basic arduino-test
patch, but still the crashes occur when I activate more than 2 analog
inputs. I'll experiment with different baud rates, go back to a usb
connection rather than the xbee wireless system and keep trying to identify
the source of the problem. I'll get back to you if I learn anything new.
Below is the data produced by the event viewer in Windows in case it means
anything to you.


pd.exe	
			0.0.0.0	
			47148d16	
			pd.dll	
			0.0.0.0	
			47148d15	
			c0000005	
			00004e04	
			17ec	
			01c89bd26543018e	

Nick.

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 11 April 2008 18:30
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs



Let's keep this on the list since it could be generally useful.

In order to get to the next step, you should try to isolate the problem, to
see where the crash is actually happening. Otherwise, there are far too many
possibilities for me to try guessing. Ideally, you could make a simple patch
that reproduces the crash.

.hc

On Apr 11, 2008, at 3:01 AM, nick burge wrote:


Firmata, Pduino and xbees. are all set to communicate at 19200 baud.
Nick 

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 10 April 2008 23:57
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs





What baud are you running each at? IIRC, the XBee needs a strange value.


.hc
On Apr 10, 2008, at 5:52 PM, nick burge wrote:


I wish I knew. I'm loading the arduino-test patch with no other objects or
abstractions so as to eliminate other suspects. Still PD crashes when I
enable more than 2 analogIns.
Would it help to speed up or slow down the xbee connection?

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 10 April 2008 23:12
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs



The code and the electrics are quite separate. If the electrics work with
one firmware, then they'll work with another. The question is, what is the
"it" that grinds to a halt.

.hc

On Apr 10, 2008, at 4:17 PM, nick burge wrote:


Yes, I've got the latest version....maybe a silly question...but could it be
that Pduino is optimised for sensors working on a supply of 5v. because the
phidget voltage dividers i've got my FSRs attached to come with a
potentiometer that alters the resistance of the circuit...with pduino i can
only activate 2 at a time before it all grinds to a halt...on arduino2PD i
can activate all six without any problem. Strange. 
Nick.

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 10 April 2008 21:51
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs



I've never run on Vista before, so I can't say much about that. I have run
on Debian, Ubuntu, and Mac OS X. It shouldn't matter what is generating the
data on the arduino, the messages coming to Pd via the serial port should be
all the same. 

Are you using the latest version:
http://at.or.at/hans/pd/Pduino-0.3.1.zip

.hc

On Apr 10, 2008, at 12:57 PM, nick burge wrote:


Hello Hans-Christoph, I am using PD 0.39.3 extended. on a windows vista
system. Its PD that crashes, or "stops working" as Vista so nicely puts it,
when I connect the FSRs.
I have arduino connecting via wireless xbees at 19200 baud.
I also use an infra red distance sensor that gives no problem.
I've been routing the data from the FSRs through the autoscale object.
Maybe I should find a way to reduce the amount of data being sampled...every
40ms for example? How would I do that?
Nick.

  _____  

From: Hans-Christoph Steiner [mailto:hans at eds.org] 
Sent: 10 April 2008 17:25
To: nick burge
Cc: Pd List
Subject: Re: [PD] pduino and FSRs



Which program crashes? Which version are you using? You will get a lot of
data, from 6 sensors, Pduino/Firmata will read them all every 20ms. I have
never seen a crash using [arduino], except when I unplug the arduino when Pd
is connected to it, so I suspect the problem lies elsewhere. 

.hc

On Apr 10, 2008, at 11:16 AM, nick burge wrote:


I have a little problem using Pduino and some force sensing resistors that I
am using in conjunction with phidget voltage dividers....they seem to crash
the program as soon as I activate more than 1 at a time..... 
Should I be applying some sort of filter to the data stream?
Arduino2PD seems more robust, allowing me to activate all 6 analog inputs at
once.

Nick Burge.
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