Created a PWM demo using the newly introduced defines to

manipulate PWM frequency.

demo/Makefile.am

@@ -4,7 +4,7 @@ noinst_PROGRAMS = \
 	choose_routing cmd do_waveform dio eeprom_dump gpct_buffered_counting \
 	gpct_encoder gpct_pulse_generator \
 	gpct_simple_counting inp inpn insn ledclock \
-	mmap outp poll receiver select \
+	mmap outp poll receiver select pwm \
 	sender sigio sv tut1 tut2 tut3
 
 noinst_HEADERS = examples.h
@@ -101,6 +101,11 @@ poll_SOURCES = poll.c common.c
 poll_CFLAGS = $(COMEDILIB_CFLAGS)
 poll_LDADD = $(COMEDILIB_LIBS)
 
+pwm_SOURCES = pwm.c common.c
+pwm_CFLAGS = $(COMEDILIB_CFLAGS)
+pwm_LDADD = $(COMEDILIB_LIBS)
+
+
 receiver_SOURCES = receiver.c common.c
 receiver_CFLAGS = $(COMEDILIB_CFLAGS)
 receiver_LDADD = $(COMEDILIB_LIBS)

demo/README

@@ -136,6 +136,11 @@ outp <value>:
 	Write one <value> to one channel of one subdevice.  Requires
 	a digital or analog output subdevice.
 
+pwm:
+	controls PWM devices. Use the option -N 0 and -N 1 to switch
+	it on / off respectively. Call with no arguments to get
+	a help screen.
+
 receiver:
 	This demo is meant to be used in conjunction with the sender
 	demo.  Receiver requires a digital input subdevice, and sender

demo/pwm.c

@@ -0,0 +1,156 @@
+#include <stdio.h>
+#include <comedilib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+/*
+ * A little pwm demo
+ * Part of Comedilib
+ *
+ * Copyright (c) 2012 Bernd Porr <berndporr@f2s.com>
+ *
+ * This file may be freely modified, distributed, and combined with
+ * other software, as long as proper attribution is given in the
+ * source code.
+ */
+
+#include <errno.h>
+#include <getopt.h>
+#include <ctype.h>
+#include <string.h>
+#include "examples.h"
+
+// the option -n is used to switch on/off the pwm
+
+int main(int argc, char *argv[])
+{
+        int ret,i;
+	comedi_insn insn;
+	lsampl_t d[5];
+	comedi_t *device;
+
+        int freq;
+
+	struct parsed_options options;
+
+	init_parsed_options(&options);
+	options.freq = -1;
+	// we hijack this option to switch it on or off
+	options.n_scan = -1;
+	options.value = -1;
+	parse_options(&options, argc, argv);
+
+	if ((options.value==-1)&&(options.n_scan==-1)&&(options.freq==-1)) {
+		fprintf(stderr,
+			"Usage: %s OPTIONS duty_cycle\n"
+			"options: \n"
+			"     -N 0    switches PWM off\n"
+			"     -N 1    switches PWM on\n"
+                        "     -N 2    enquires the max value for the duty cycle\n"
+			"     -F FREQ sets the PWM frequency\n",
+			argv[0]);
+	}
+
+        device = comedi_open(options.filename);
+        if(!device){
+		comedi_perror(options.filename);
+		exit(-1);
+        }
+
+	options.subdevice = comedi_find_subdevice_by_type(device,COMEDI_SUBD_PWM,0);
+	if (options.verbose)
+		printf("PWM subdevice autodetection gave subdevice number %d\n",
+		       options.subdevice);
+
+	if(options.n_scan==2) {
+		printf("%d\n",comedi_get_maxdata(device,options.subdevice,0));
+		close(device);
+		exit(0);
+	}       
+
+	insn.insn=INSN_CONFIG;
+	insn.data=d;
+	insn.subdev=options.subdevice;
+	insn.chanspec=CR_PACK(0,0,0);
+
+	if(options.n_scan==1) {
+		d[0] = INSN_CONFIG_ARM;
+		d[1] = 0;
+		insn.n=2;
+		ret=comedi_do_insn(device,&insn);
+		if(ret < 0){
+			fprintf(stderr,"Could not switch on:%d\n",ret);
+			comedi_perror(options.filename);
+			exit(-1);
+		}
+	}
+	if(options.n_scan==0) {
+		d[0] = INSN_CONFIG_DISARM;
+		d[1] = 0;
+		insn.n=1;
+		ret=comedi_do_insn(device,&insn);
+		if(ret < 0){
+			fprintf(stderr,"Could not switch off:%d\n",ret);
+			comedi_perror(options.filename);
+			exit(-1);
+		}
+	}
+	if(options.freq>0) {
+		freq = options.freq;
+		d[0] = INSN_CONFIG_PWM_SET_PERIOD;
+		d[1] = 1E9/freq;
+		insn.n=2;
+		ret=comedi_do_insn(device,&insn);
+		if(ret < 0){
+			fprintf(stderr,"Could set frequ:%d\n",ret);
+			comedi_perror(options.filename);
+			exit(-1);
+		}
+	}
+		
+	d[0] = INSN_CONFIG_GET_PWM_STATUS;
+	insn.n=2;
+	ret=comedi_do_insn(device,&insn);
+	if(ret < 0){
+		fprintf(stderr,"Could not get status:%d insn=%d\n",
+			ret,
+			d[0]);
+		comedi_perror(options.filename);
+		exit(-1);
+	}
+	if (options.verbose) {
+		if (d[1])
+			fprintf(stderr,
+				"PWM is on.\n");
+		else
+			fprintf(stderr,
+				"PWM is off.\n");
+	}
+	d[0] = INSN_CONFIG_PWM_GET_PERIOD;
+	insn.n=2;
+	ret=comedi_do_insn(device,&insn);
+	if(ret < 0){
+		fprintf(stderr,"Could get frequ:%d\n",ret);
+		comedi_perror(options.filename);
+		exit(-1);
+	}
+	freq = 1E9 / d[1];
+	if (options.verbose)
+		fprintf(stderr,"PWM frequency is %d\n", freq);
+
+	if (options.value>=0)
+
+		if(comedi_data_write(device,
+				     options.subdevice, 
+				     options.channel,
+				     0,
+				     0,
+				     options.value)<0)
+		{
+			fprintf(stderr,"error setting the pwm duty cycle on ");
+			comedi_perror(options.filename);
+			exit(1);
+		}
+
+        return 0;
+}