and an example.
# Should not alter anything below this line
###############################################################################
-SRC = test1.c test2.c speed.c lcd.c wfi.c piface.c gertboard.c nes.c delayTest.c
+SRC = test1.c test2.c speed.c lcd.c wfi.c piface.c gertboard.c nes.c delayTest.c softPwm.c
-OBJ = test1.o test2.o speed.o lcd.o wfi.o piface.o gertboard.o nes.o delayTest.o
+OBJ = test1.o test2.o speed.o lcd.o wfi.o piface.o gertboard.o nes.o delayTest.o softPwm.o
-all: test1 test2 speed lcd wfi piface gertboard nes
+all: test1 test2 speed lcd wfi piface gertboard nes softPwm
test1: test1.o
@echo [link]
@echo [link]
$(CC) -o $@ nes.o $(LDFLAGS) $(LIBS) -lm
+softPwm: softPwm.o
+ @echo [link]
+ $(CC) -o $@ softPwm.o $(LDFLAGS) $(LIBS) -lm -lpthread
+
delayTest: delayTest.o
@echo [link]
@$(CC) -c $(CFLAGS) $< -o $@
clean:
- rm -f $(OBJ) *~ core tags test1 test2 speed lcd wfi piface gertboard nes delayTest
+ rm -f $(OBJ) *~ core tags test1 test2 speed lcd wfi piface gertboard nes delayTest softPwm
tags: $(SRC)
@echo [ctags]
--- /dev/null
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#include <wiringPi.h>
+#include <softPwm.h>
+
+#define RANGE 100
+#define NUM_LEDS 12
+
+int ledMap [NUM_LEDS] = { 0, 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13 } ;
+
+int values [NUM_LEDS] = { 0, 17, 32, 50, 67, 85, 100, 85, 67, 50, 32, 17 } ;
+
+int main ()
+{
+ int i, j ;
+
+ if (wiringPiSetup () == -1)
+ {
+ fprintf (stdout, "oops: %s\n", strerror (errno)) ;
+ return 1 ;
+ }
+
+ for (i = 0 ; i < NUM_LEDS ; ++i)
+ {
+ softPwmCreate (ledMap [i], 0, RANGE) ;
+ printf ("%3d, %3d, %3d\n", i, ledMap [i], values [i]) ;
+ }
+
+ for (;;)
+ {
+ for (i = 0 ; i < NUM_LEDS ; ++i)
+ softPwmWrite (ledMap [i], values [i]) ;
+
+ delay (50) ;
+
+ i = values [0] ;
+ for (j = 0 ; j < NUM_LEDS - 1 ; ++j)
+ values [j] = values [j + 1] ;
+ values [NUM_LEDS - 1] = i ;
+ }
+}
SRC = wiringPi.c wiringPiFace.c wiringSerial.c wiringShift.c \
gertboard.c \
piNes.c \
- lcd.c piHiPri.c piThread.c
+ lcd.c piHiPri.c piThread.c softPwm.c
OBJ = wiringPi.o wiringPiFace.o wiringSerial.o wiringShift.o \
gertboard.o \
piNes.o \
- lcd.o piHiPri.o piThread.o
+ lcd.o piHiPri.o piThread.o softPwm.o
all: $(TARGET)
install -m 0644 wiringShift.h /usr/local/include
install -m 0644 gertboard.h /usr/local/include
install -m 0644 piNes.h /usr/local/include
+ install -m 0644 softPwm.h /usr/local/include
install -m 0644 lcd.h /usr/local/include
install -m 0644 libwiringPi.a /usr/local/lib
--- /dev/null
+/*
+ * softPwm.c:
+ * Provide 2 channels of software driven PWM.
+ * Copyright (c) 2012 Gordon Henderson
+ ***********************************************************************
+ * This file is part of wiringPi:
+ * https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ * wiringPi is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * wiringPi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with wiringPi.
+ * If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+
+#include "wiringPi.h"
+#include "softPwm.h"
+
+#define MAX_PINS 64
+
+// The PWM Frequency is derived from the "pulse time" below. Essentially,
+// the frequency is a function of the range and this pulse time.
+// The total period will be range * pulse time in uS, so a pulse time
+// of 100 and a range of 100 gives a period of 100 * 100 = 10,000 uS
+// which is a frequency of 100Hz.
+//
+// It's possible to get a higher frequency by lowering the pulse time,
+// however CPU uage will skyrocket as wiringPi uses a hard-loop to time
+// periods under 100uS - this is because the Linux timer calls are just
+// accurate at all, and have an overhead.
+//
+// Another way to increase the frequency is to reduce the range - however
+// that reduces the overall output accuracy...
+
+#define PULSE_TIME 100
+
+static int marks [MAX_PINS] ;
+static int range [MAX_PINS] ;
+
+int newPin = -1 ;
+
+
+/*
+ * softPwmThread:
+ * Thread to do the actual PWM output
+ *********************************************************************************
+ */
+
+static PI_THREAD (softPwmThread)
+{
+ int pin, mark, space ;
+
+ pin = newPin ;
+ newPin = -1 ;
+
+ piHiPri (50) ;
+
+ for (;;)
+ {
+ mark = marks [pin] ;
+ space = range [pin] - mark ;
+
+ if (mark != 0)
+ digitalWrite (pin, HIGH) ;
+ delayMicroseconds (mark * 100) ;
+
+ if (space != 0)
+ digitalWrite (pin, LOW) ;
+ delayMicroseconds (space * 100) ;
+ }
+
+ return NULL ;
+}
+
+void softPwmWrite (int pin, int value)
+{
+ marks [pin] = value ;
+}
+
+
+/*
+ * softPwmCreate:
+ * Create a new PWM thread.
+ *********************************************************************************
+ */
+
+int softPwmCreate (int pin, int initialValue, int pwmRange)
+{
+ int res ;
+
+ pinMode (pin, OUTPUT) ;
+ digitalWrite (pin, LOW) ;
+
+ marks [pin] = initialValue ;
+ range [pin] = pwmRange ;
+
+ newPin = pin ;
+ res = piThreadCreate (softPwmThread) ;
+
+ while (newPin != -1)
+ delay (1) ;
+
+ return res ;
+}
--- /dev/null
+/*
+ * softPwm.h:
+ * Provide 2 channels of software driven PWM.
+ * Copyright (c) 2012 Gordon Henderson
+ ***********************************************************************
+ * This file is part of wiringPi:
+ * https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ * wiringPi is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * wiringPi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with wiringPi.
+ * If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+extern int setupSoftPwm (int pin) ;
+extern int softPwmCreate (int pin, int value, int range) ;
+extern void softPwmWrite (int pin, int value) ;
~ianmdlvl / wiringPi.git / commitdiff