217 lines
6.3 KiB
C
217 lines
6.3 KiB
C
// Communicating with a PCA9685 pwm device via linux i2c
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//
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// Copyright (C) 2017 Kevin O'Connor <kevin@koconnor.net>
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//
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// This file may be distributed under the terms of the GNU GPLv3 license.
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#include <fcntl.h> // open
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#include <linux/i2c-dev.h> // I2C_SLAVE
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#include <stdio.h> // snprintf
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#include <sys/ioctl.h> // ioctl
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#include <unistd.h> // write
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#include "basecmd.h" // oid_alloc
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#include "board/misc.h" // timer_from_us
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#include "command.h" // DECL_COMMAND
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#include "internal.h" // report_errno
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#include "sched.h" // DECL_SHUTDOWN
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/****************************************************************
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* Low-level i2c
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****************************************************************/
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#define P9_MODE1 0x00
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#define P9_PRESCALE 0xfe
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#define CHANNEL_MAX 15
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#define CHANNEL_ALL 61
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#define VALUE_MAX 4096
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#define OSC_MHZ 25
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#define CLOCK_MHZ timer_from_us(1)
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struct i2c_s {
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uint8_t bus;
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uint8_t addr;
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uint32_t cycle_ticks;
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int fd;
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};
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static struct i2c_s devices[16];
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static int devices_count;
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static void
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pca9685_write(int fd, uint8_t channel, uint16_t value)
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{
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uint8_t full_on = 0x00;
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if (value >= VALUE_MAX) {
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full_on = 0x10;
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value = 0x0000;
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} else if (!value) {
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value = 0x1000;
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}
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uint8_t msg[5] = { channel*4 + 0x06, 0x00, full_on, value, value >> 8 };
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int ret = write(fd, msg, sizeof(msg));
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if (ret < 0) {
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report_errno("write value i2c", ret);
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try_shutdown("Unable to update PCA9685 value");
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}
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}
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static int
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open_i2c(uint8_t bus, uint8_t addr, uint32_t cycle_ticks)
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{
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// Find existing device (if already opened)
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int i;
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for (i=0; i<devices_count; i++)
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if (devices[i].bus == bus && devices[i].addr == addr) {
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if (cycle_ticks != devices[i].cycle_ticks)
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shutdown("All PCA9685 channels must have the same cycle_ticks");
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return devices[i].fd;
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}
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// Setup new I2C device
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if (devices_count >= ARRAY_SIZE(devices))
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shutdown("Too many i2c devices");
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char fname[256];
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snprintf(fname, sizeof(fname), "/dev/i2c-%d", bus);
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int fd = open(fname, O_RDWR|O_CLOEXEC);
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if (fd < 0) {
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report_errno("open i2c", fd);
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shutdown("Unable to open i2c device");
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}
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int ret = ioctl(fd, I2C_SLAVE, addr);
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if (ret < 0) {
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report_errno("ioctl i2c", fd);
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shutdown("Unable to set address on i2c device");
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}
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ret = set_non_blocking(fd);
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if (ret < 0)
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shutdown("Unable to set non-blocking on i2c device");
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// Init PCA9685
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const uint8_t sleep_msg[2] = { P9_MODE1, 0x31 };
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ret = write(fd, sleep_msg, sizeof(sleep_msg));
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if (ret < 0) {
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report_errno("write sleep i2c", ret);
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shutdown("Unable to sleep PCA9685");
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}
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uint32_t freq = DIV_ROUND_CLOSEST(OSC_MHZ*cycle_ticks, 4096*CLOCK_MHZ) - 1;
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freq = freq > 0xff ? 0xff : (freq < 0x03 ? 0x03 : freq);
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uint8_t freq_msg[2] = { P9_PRESCALE, freq };
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ret = write(fd, freq_msg, sizeof(freq_msg));
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if (ret < 0) {
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report_errno("write freq i2c", ret);
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shutdown("Unable to set freq on PCA9685");
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}
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const uint8_t wake_msg[2] = { P9_MODE1, 0x21 };
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ret = write(fd, wake_msg, sizeof(wake_msg));
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if (ret < 0) {
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report_errno("write unsleep i2c", ret);
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shutdown("Unable to wake PCA9685");
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}
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usleep(500);
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pca9685_write(fd, CHANNEL_ALL, 0);
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devices[devices_count].bus = bus;
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devices[devices_count].addr = addr;
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devices[devices_count].cycle_ticks = cycle_ticks;
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devices[devices_count].fd = fd;
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devices_count++;
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return fd;
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}
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/****************************************************************
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* Command interface
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****************************************************************/
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struct i2cpwm_s {
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struct timer timer;
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int fd;
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uint8_t channel;
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uint16_t value, default_value;
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uint32_t max_duration;
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};
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DECL_CONSTANT(PCA9685_MAX, VALUE_MAX);
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static uint_fast8_t
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pca9685_end_event(struct timer *timer)
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{
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shutdown("Missed scheduling of next pca9685 event");
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}
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static uint_fast8_t
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pca9685_event(struct timer *timer)
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{
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struct i2cpwm_s *p = container_of(timer, struct i2cpwm_s, timer);
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pca9685_write(p->fd, p->channel, p->value);
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if (p->value == p->default_value || !p->max_duration)
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return SF_DONE;
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p->timer.waketime += p->max_duration;
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p->timer.func = pca9685_end_event;
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return SF_RESCHEDULE;
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}
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void
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command_config_pca9685(uint32_t *args)
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{
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uint8_t bus = args[1], addr = args[2], channel = args[3];
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uint16_t value = args[5], default_value = args[6];
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if (channel > CHANNEL_MAX || value > VALUE_MAX || default_value > VALUE_MAX)
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shutdown("Invalid pca9685 channel or value");
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int fd = open_i2c(bus, addr, args[4]);
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if (value)
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pca9685_write(fd, channel, value);
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struct i2cpwm_s *p = oid_alloc(args[0], command_config_pca9685, sizeof(*p));
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p->fd = fd;
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p->channel = channel;
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p->default_value = default_value;
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p->max_duration = args[7];
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}
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DECL_COMMAND(command_config_pca9685, "config_pca9685 oid=%c bus=%c addr=%c"
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" channel=%c cycle_ticks=%u value=%hu"
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" default_value=%hu max_duration=%u");
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void
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command_schedule_pca9685_out(uint32_t *args)
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{
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struct i2cpwm_s *p = oid_lookup(args[0], command_config_pca9685);
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sched_del_timer(&p->timer);
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p->timer.func = pca9685_event;
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p->timer.waketime = args[1];
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p->value = args[2];
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if (p->value > VALUE_MAX)
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shutdown("Invalid pca9685 value");
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sched_add_timer(&p->timer);
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}
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DECL_COMMAND(command_schedule_pca9685_out,
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"schedule_pca9685_out oid=%c clock=%u value=%hu");
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void
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command_set_pca9685_out(uint32_t *args)
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{
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uint8_t bus = args[0], addr = args[1], channel = args[2];
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uint16_t value = args[4];
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if (channel > CHANNEL_MAX || value > VALUE_MAX)
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shutdown("Invalid pca9685 channel or value");
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int fd = open_i2c(bus, addr, args[3]);
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pca9685_write(fd, channel, value);
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}
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DECL_COMMAND(command_set_pca9685_out, "set_pca9685_out bus=%c addr=%c"
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" channel=%c cycle_ticks=%u value=%hu");
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void
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pca9685_shutdown(void)
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{
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int i;
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for (i=0; i<devices_count; i++)
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pca9685_write(devices[i].fd, CHANNEL_ALL, 0);
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uint8_t j;
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struct i2cpwm_s *p;
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foreach_oid(j, p, command_config_pca9685) {
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if (p->default_value)
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pca9685_write(p->fd, p->channel, p->default_value);
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}
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}
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DECL_SHUTDOWN(pca9685_shutdown);
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