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gohaigohai
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IO: Implement Raspbian-only method for setting pull{up,down} resistors
Aarch64 version compiled courtesy of @xranby
1 parent fa91706 commit ad9884b

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9 files changed

+184
-3
lines changed

9 files changed

+184
-3
lines changed

‎java/libraries/io/examples/SimpleInput/SimpleInput.pde‎

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,10 @@ import processing.io.*;
55
// see setup.png in the sketch folder for wiring details
66

77
void setup() {
8-
GPIO.pinMode(4, GPIO.INPUT);
8+
// INPUT_PULLUP enables the built-in pull-up resistor for this pin
9+
// left alone, the pin will read as HIGH
10+
// connected to ground (via e.g. a button or switch) it will read LOW
11+
GPIO.pinMode(4, GPIO.INPUT_PULLUP);
912
}
1013

1114
void draw() {

‎java/libraries/io/library/linux-arm64/libprocessing-io.so‎

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‎java/libraries/io/library/linux-armv6hf/libprocessing-io.so‎

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‎java/libraries/io/library/linux32/libprocessing-io.so‎

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‎java/libraries/io/library/linux64/libprocessing-io.so‎

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‎java/libraries/io/src/native/iface.h‎

Lines changed: 24 additions & 0 deletions
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‎java/libraries/io/src/native/impl.c‎

Lines changed: 138 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@
3030
#include <stdlib.h>
3131
#include <string.h>
3232
#include <sys/ioctl.h>
33+
#include <sys/mman.h>
3334
#include <sys/param.h>
3435
#include <time.h>
3536
#include <unistd.h>
@@ -120,6 +121,143 @@ JNIEXPORT jint JNICALL Java_processing_io_NativeInterface_writeFile
120121
}
121122

122123

124+
JNIEXPORT jint JNICALL Java_processing_io_NativeInterface_raspbianGpioMemRead
125+
(JNIEnv *env, jclass cls, jint offset)
126+
{
127+
// validate offset
128+
if (4096 <= offset) {
129+
return -EINVAL;
130+
}
131+
132+
int file = open("/dev/gpiomem", O_RDWR|O_SYNC);
133+
if (file < 0) {
134+
return -errno;
135+
}
136+
137+
uint32_t *mem = mmap(NULL, 4096, PROT_READ, MAP_SHARED, file, 0);
138+
if (mem == MAP_FAILED) {
139+
close(file);
140+
return -errno;
141+
}
142+
143+
uint32_t value = mem[offset];
144+
145+
munmap(mem, 4096);
146+
close(file);
147+
return value;
148+
}
149+
150+
151+
JNIEXPORT jint JNICALL Java_processing_io_NativeInterface_raspbianGpioMemWrite
152+
(JNIEnv *env, jclass cls, jint offset, jint mask, jint value)
153+
{
154+
// validate offset
155+
if (4096 <= offset) {
156+
return -EINVAL;
157+
}
158+
159+
int file = open("/dev/gpiomem", O_RDWR|O_SYNC);
160+
if (file < 0) {
161+
return -errno;
162+
}
163+
164+
uint32_t *mem = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, file, 0);
165+
if (mem == MAP_FAILED) {
166+
close(file);
167+
return -errno;
168+
}
169+
170+
mem[offset] = (mem[offset] & ~mask) | (value & mask);
171+
172+
munmap(mem, 4096);
173+
close(file);
174+
return 1; // number of bytes written
175+
}
176+
177+
178+
#define BCM2835_GPPUD_OFFSET (0x94 >> 2)
179+
#define BCM2835_GPPUDCLK0_OFFSET (0x98 >> 2)
180+
#define BCM2835_GPPUDCLK1_OFFSET (0x9c >> 2)
181+
182+
JNIEXPORT jint JNICALL Java_processing_io_NativeInterface_raspbianGpioMemSetPinBias
183+
(JNIEnv *env, jclass cls, jint gpio, jint mode)
184+
{
185+
int ret = 0; // success
186+
187+
int file = open("/dev/gpiomem", O_RDWR|O_SYNC);
188+
if (file < 0) {
189+
return -errno;
190+
}
191+
192+
uint32_t *mem = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, file, 0);
193+
if (mem == MAP_FAILED) {
194+
close(file);
195+
return -errno;
196+
}
197+
198+
// validate arguments
199+
if (gpio < 0 || 53 < gpio) {
200+
ret = -EINVAL;
201+
goto out;
202+
}
203+
204+
// see BCM2835 datasheet, p. 101
205+
uint32_t pud;
206+
if (mode == 0) {
207+
pud = 0; // floating
208+
} else if (mode == 2) {
209+
pud = 2; // pull-up
210+
} else if (mode == 3) {
211+
pud = 1; // pull-down
212+
} else {
213+
ret = -EINVAL;
214+
goto out;
215+
}
216+
217+
/*
218+
* From the BCM2835 datasheet, p. 101:
219+
*
220+
* The following sequence of events is required:
221+
* 1. Write to GPPUD to set the required control signal (i.e. Pull-up or
222+
* Pull-Down or neither to remove the current Pull-up/down)
223+
* 2. Wait 150 cycles – this provides the required set-up time for the
224+
* control signal
225+
* 3. Write to GPPUDCLK0/1 to clock the control signal into the GPIO pads
226+
* you wish to modify – NOTE only the pads which receive a clock will
227+
* be modified, all others will retain their previous state.
228+
* 4. Wait 150 cycles – this provides the required hold time for the
229+
* control signal
230+
* 5. Write to GPPUD to remove the control signal
231+
* 6. Write to GPPUDCLK0/1 to remove the clock
232+
*/
233+
234+
// python-gpiozero uses a delay of 214 ns, so we do the same
235+
struct timespec wait;
236+
wait.tv_sec = 0;
237+
wait.tv_nsec = 214;
238+
239+
mem[BCM2835_GPPUD_OFFSET] = pud;
240+
nanosleep(&wait, NULL);
241+
if (gpio < 32) {
242+
mem[BCM2835_GPPUDCLK0_OFFSET] = 1 << gpio;
243+
} else {
244+
mem[BCM2835_GPPUDCLK1_OFFSET] = 1 << (gpio-32);
245+
}
246+
nanosleep(&wait, NULL);
247+
mem[BCM2835_GPPUD_OFFSET] = 0;
248+
if (gpio < 32) {
249+
mem[BCM2835_GPPUDCLK0_OFFSET] = 0;
250+
} else {
251+
mem[BCM2835_GPPUDCLK1_OFFSET] = 0;
252+
}
253+
254+
out:
255+
munmap(mem, 4096);
256+
close(file);
257+
return ret;
258+
}
259+
260+
123261
JNIEXPORT jint JNICALL Java_processing_io_NativeInterface_pollDevice
124262
(JNIEnv *env, jclass cls, jstring _fn, jint timeout)
125263
{

‎java/libraries/io/src/processing/io/GPIO.java‎

Lines changed: 15 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -328,7 +328,7 @@ public static void noInterrupts() {
328328
/**
329329
* Configures a pin to act either as input or output
330330
* @param pin GPIO pin
331-
* @param mode GPIO.INPUT or GPIO.OUTPUT
331+
* @param mode GPIO.INPUT, GPIO.INPUT_PULLUP, GPIO.INPUT_PULLDOWN, or GPIO.OUTPUT
332332
* @see digitalRead
333333
* @see digitalWrite
334334
* @see releasePin
@@ -369,16 +369,29 @@ public static void pinMode(int pin, int mode) {
369369
String out;
370370
if (mode == INPUT) {
371371
out = "in";
372+
373+
// attempt to disable any pre-set pullups on the Raspberry Pi
374+
NativeInterface.raspbianGpioMemSetPinBias(pin, mode);
375+
372376
} else if (mode == OUTPUT) {
373377
if (values.get(pin)) {
374378
out = "high";
375379
} else {
376380
out = "low";
377381
}
378382
} else if (mode == INPUT_PULLUP || mode == INPUT_PULLDOWN) {
383+
out = "in";
384+
385+
// attempt to set pullups on the Raspberry Pi
386+
ret = NativeInterface.raspbianGpioMemSetPinBias(pin, mode);
387+
if (ret == -2) { // NOENT
388+
System.err.println("Setting pullup or pulldown resistors is currently only supported on the Raspberry Pi running Raspbian. Continuing without.");
389+
} else if (ret < 0) {
390+
System.err.println("Error setting pullup or pulldown resistors: " + NativeInterface.getError(ret) + ". Continuing without.");
391+
}
379392
// currently this can't be done in a non-platform-specific way, see
380393
// http://lists.infradead.org/pipermail/linux-rpi-kernel/2015-August/002146.html
381-
throw new RuntimeException("Not yet implemented");
394+
382395
} else {
383396
throw new IllegalArgumentException("Unknown mode");
384397
}

‎java/libraries/io/src/processing/io/NativeInterface.java‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -62,6 +62,9 @@ public static int writeFile(String fn, String out) {
6262
}
6363

6464
/* GPIO */
65+
public static native int raspbianGpioMemRead(int offset);
66+
public static native int raspbianGpioMemWrite(int offset, int mask, int value);
67+
public static native int raspbianGpioMemSetPinBias(int gpio, int mode);
6568
public static native int pollDevice(String fn, int timeout);
6669
/* I2C */
6770
public static native int transferI2c(int handle, int slave, byte[] out, byte[] in);

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