Le 14/10/2014 19:51, Martin Peach a écrit :
Oh sorry, I thought you were using an arduino.
I'm using an emulated arduino, it's called pcduino and it's the most
powerfull miniPC we can actually find.
PureData is running so fine on it even through ssh there is no latency
like I've encountered on raspberry,
and Multitrack USB soundcards runs greatly on it.
Martin
On Tue, Oct 14, 2014 at 1:16 PM, Colet Patrice <[email protected]
<mailto:[email protected]>> wrote:
Le 14/10/2014 15:06, Martin Peach a écrit :
Not sure why it segfaults, just want to say that that method is
really bad. Because of Pd's control rate as well as the serial
interface latency, your timing will be really sketchy. The way to
do what you want is to implement the ranging entirely on the
arduino and send the values back to Pd via [comport]. So a Pd
[pulseIn] object shoud simply send a request to the arduino to
start a pulse and return the time. It could be implemented as an
abstraction containing [comport].
I'm not using serial to read gpio state but fopen() (may be
fopen() is not fast enough), like in a raspberry (but it's not on
raspberry), I will try to do this with python and use pdsend for
retrieving value into puredata.
thank you for the advice.
pc
Martin
On Mon, Oct 13, 2014 at 9:29 PM, Colet Patrice
<[email protected] <mailto:[email protected]>> wrote:
Hello, I'm trying to implement the pulseIn() function we can
find in arduino libraries into an external.
I couldn't make it work because some part doesn't seem to
behave like I expect so I'm wondering if it's caused by
puredata process,
so maybe someone in the list could enlight me about that.
The purpose of the external is about using an ultrasound
sensor connected on gpio that require a microsecond timer for
getting distance like this:
//here is a custom timer using a struct provided by pcduino
headers:
#include core.h
unsigned long pat_micros() {
struct timeval tv;
gettimeofday(&tv,NULL);
return tv.tv_sec*(uint64_t)1000000+tv.tv_usec;
}
//here is the custom pulseIn() function:
unsigned long pat_pulseIn(t_pdpcduino *x, int pin)
{
unsigned long timeout = 100000;
unsigned long start = pat_micros();
while( pdpcduino_gpio_read2 (x, pin) == 1 )
if( pat_micros() - start > timeout )
return 0;
// this is where I'm getting a segmentation fault:
while ( pdpcduino_gpio_read2 (x, pin) == 0 )
if( pat_micros() - start > timeout )
return 0;
//...
unsigned long value = pat_micros();
while( pdpcduino_gpio_read2 (x, pin) == 1 )
if( pat_micros() - start > timeout )
return 0;
return pat_micros() - value;
}
//...
If I reduce the timeout number, segfault comes randomly after
this function has been triggered, so I'm wondering if this
method is really appropriate,
is there an exemple of external (containing such while loops)
I could get inspired from to write this pulseIn() function?
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