BBIO_err pwm_set_duty_cycle(const char *key, float duty) {
int len;
char buffer[20];
struct pwm_exp *pwm;
if (duty < 0.0 || duty > 100.0)
return BBIO_INVARG;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_duty_cycle: %s couldn't find key", key);
return BBIO_GEN;
}
pwm->duty = duty;
pwm->duty_ns = (unsigned long)(pwm->period_ns * (duty / 100.0));
len = snprintf(buffer, sizeof(buffer), "%lu", pwm->duty_ns);
lseek(pwm->duty_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->duty_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_duty_cycle: %s couldn't write duty: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
syslog(LOG_DEBUG, "Adafruit_BBIO: pwm_set_duty_cycle: %s %f OK", key, duty);
return BBIO_OK;
}
int pwm_set_frequency(const char *key, float freq) {
int len;
char buffer[20];
unsigned long period_ns;
struct pwm_exp *pwm;
if (freq <= 0.0)
return -1;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
period_ns = (unsigned long)(1e9 / freq);
if (period_ns != pwm->period_ns) {
pwm->period_ns = period_ns;
len = snprintf(buffer, sizeof(buffer), "%lu", period_ns);
write(pwm->period_fd, buffer, len);
}
return 1;
}
int pwm_set_polarity(const char *key, int polarity) {
int len;
char buffer[7]; /* allow room for trailing NUL byte */
struct pwm_exp *pwm;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
len = snprintf(buffer, sizeof(buffer), "%d", polarity);
write(pwm->polarity_fd, buffer, len);
return 0;
}
int softpwm_set_frequency(const char *key, float freq) {
struct softpwm *pwm;
if (freq <= 0.0)
return -1;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
pthread_mutex_lock(pwm->params_lock);
pwm->params.freq = freq;
pthread_mutex_unlock(pwm->params_lock);
return 0;
}
int softpwm_set_duty_cycle(const char *key, float duty) {;
struct softpwm *pwm;
if (duty < 0.0 || duty > 100.0)
return -1;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
pthread_mutex_lock(pwm->params_lock);
pwm->params.duty = duty;
pthread_mutex_unlock(pwm->params_lock);
return 0;
}
int softpwm_set_polarity(const char *key, int polarity) {
struct softpwm *pwm;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
if (polarity < 0 || polarity > 1) {
return -1;
}
pthread_mutex_lock(pwm->params_lock);
pwm->params.polarity = polarity;
pthread_mutex_unlock(pwm->params_lock);
return 0;
}
int pwm_set_duty_cycle(const char *key, float duty) {
int len;
char buffer[20];
struct pwm_exp *pwm;
if (duty < 0.0 || duty > 100.0)
return -1;
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
return -1;
}
pwm->duty = (unsigned long)(pwm->period_ns * (duty / 100.0));
len = snprintf(buffer, sizeof(buffer), "%lu", pwm->duty);
write(pwm->duty_fd, buffer, len);
return 0;
}
// Only works before chip is enabled
BBIO_err pwm_set_polarity(const char *key, int polarity) {
int len;
char buffer[9]; /* allow room for trailing NUL byte */
struct pwm_exp *pwm;
#ifdef BBBVERSION41
int enabled; /* Maintain original state */
#endif
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s couldn't find key", key);
return BBIO_GEN;
}
// polarity can't be changed with enabled.
#ifdef BBBVERSION41
// Read the current enabled status
len = 1;
memset(buffer, 0, 9); // Initialize buffer
lseek(pwm->enable_fd, 0, SEEK_SET);
if (read(pwm->enable_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s couldn't read enable: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
// If the PWM is enabled, disable it
// Can't set the polarity with device enabled
// It will be reenabled after the parameters are set
if (buffer[0] == '1') {
enabled = 1;
lseek(pwm->enable_fd, 0, SEEK_SET);
len = snprintf(buffer, sizeof(buffer), "0");
if (write(pwm->enable_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s couldn't write enable: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
}
// Treating 0 as normal, 1 as inversed
// See documentation of sysfs interface at
// https://www.kernel.org/doc/Documentation/pwm.txt
if (polarity == 0) {
len = snprintf(buffer, sizeof(buffer), "normal");
} else if (polarity == 1) {
len = snprintf(buffer, sizeof(buffer), "inversed");
} else {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s invalid argument value: %i", key, polarity);
return BBIO_INVARG;
}
#else
len = snprintf(buffer, sizeof(buffer), "%d", polarity);
#endif
lseek(pwm->polarity_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->polarity_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s couldn't write polarity: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
/* If we were enabled before, restore state */
#ifdef BBBVERSION41
if (enabled) {
lseek(pwm->enable_fd, 0, SEEK_SET);
len = snprintf(buffer, sizeof(buffer), "1");
if (write(pwm->enable_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_polarity: %s couldn't write enable: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
}
#endif
syslog(LOG_DEBUG, "Adafruit_BBIO: pwm_set_polarity: %s %i OK", key, polarity);
return BBIO_OK;
}
BBIO_err initialize_pwm(void)
{
#ifdef BBBVERSION41 // don't load overlay in 4.1+
if (!pwm_initialized) {
strncpy(ocp_dir, "/sys/devices/platform/ocp", sizeof(ocp_dir));
#else
BBIO_err err;
if (!pwm_initialized && load_device_tree("am33xx_pwm")) {
err = build_path("/sys/devices", "ocp", ocp_dir, sizeof(ocp_dir));
if (err != BBIO_OK)
{
return BBIO_SYSFS;
}
#endif
pwm_initialized = 1;
#ifdef DEBUGINFO
syslog(LOG_DEBUG, "Adafruit_BBIO: initialize_pwm: OK");
#endif
return BBIO_OK;
}
#ifdef DEBUGINFO
syslog(LOG_DEBUG, "Adafruit_BBIO: initialize_pwm: OK");
#endif
return BBIO_OK;
}
BBIO_err pwm_set_frequency(const char *key, float freq) {
int len;
char buffer[20];
unsigned long period_ns;
struct pwm_exp *pwm;
if (freq <= 0.0) {
#ifdef DEBUGINFO
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s freq %f <= 0.0", key, freq);
#endif
return BBIO_INVARG;
}
pwm = lookup_exported_pwm(key);
if (pwm == NULL) {
#ifdef DEBUGINFO
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s couldn't find key", key);
#endif
return BBIO_GEN;
}
period_ns = (unsigned long)(1e9 / freq);
// If we're going to a shorter period, update the
// duty cycle first, in order to avoid ever setting
// the period < duty cycle (which would throw error)
if (period_ns < pwm->period_ns) {
pwm->period_ns = period_ns;
// Update duty ns
pwm->duty_ns = (unsigned long)(period_ns * (pwm->duty / 100.0));
len = snprintf(buffer, sizeof(buffer), "%lu", pwm->duty_ns);
lseek(pwm->duty_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->duty_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s couldn't write duty: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
// Update period ns
len = snprintf(buffer, sizeof(buffer), "%lu", period_ns);
lseek(pwm->period_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->period_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s couldn't write period: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
} else if (period_ns > pwm->period_ns) {
pwm->period_ns = period_ns;
// Ordinarily update the period first,
// to avoid the opposite bug - kernel won't
// let us set duty greater than period
// Update period ns
len = snprintf(buffer, sizeof(buffer), "%lu", period_ns);
lseek(pwm->period_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->period_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s couldn't write period: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
// Update duty ns
pwm->duty_ns = (unsigned long)(period_ns * (pwm->duty / 100.0));
len = snprintf(buffer, sizeof(buffer), "%lu", pwm->duty_ns);
lseek(pwm->duty_fd, 0, SEEK_SET); // Seek to beginning of file
if (write(pwm->duty_fd, buffer, len) < 0) {
syslog(LOG_ERR, "Adafruit_BBIO: pwm_set_frequency: %s couldn't write duty: %i-%s",
key, errno, strerror(errno));
return BBIO_SYSFS;
}
} // else do nothing
syslog(LOG_DEBUG, "Adafruit_BBIO: pwm_set_frequency: %s %f OK", key, freq);
return BBIO_OK;
}
