int softpwm_start(const char *key, float duty, float freq, int polarity)
{
struct softpwm *new_pwm, *pwm;
pthread_t new_thread;
pthread_mutex_t *new_params_lock;
int gpio;
int ret;
if (get_gpio_number(key, &gpio) < 0)
return -1;
if (gpio_export(gpio) < 0)
return -1;
if (gpio_set_direction(gpio, OUTPUT) < 0)
return -1;
// add to list
new_pwm = malloc(sizeof(struct softpwm)); ASSRT(new_pwm != NULL);
new_params_lock = (pthread_mutex_t *)malloc(sizeof(pthread_mutex_t));
if (new_pwm == 0) {
return -1; // out of memory
}
pthread_mutex_init(new_params_lock, NULL);
pthread_mutex_lock(new_params_lock);
strncpy(new_pwm->key, key, KEYLEN); /* can leave string unterminated */
new_pwm->key[KEYLEN] = '\0'; /* terminate string */
new_pwm->gpio = gpio;
new_pwm->params.enabled = true;
new_pwm->params.stop_flag = false;
new_pwm->params_lock = new_params_lock;
new_pwm->next = NULL;
if (exported_pwms == NULL)
{
// create new list
exported_pwms = new_pwm;
} else {
// add to end of existing list
pwm = exported_pwms;
while (pwm->next != NULL)
pwm = pwm->next;
pwm->next = new_pwm;
}
pthread_mutex_unlock(new_params_lock);
ASSRT(softpwm_set_duty_cycle(new_pwm->key, duty) == 0);
ASSRT(softpwm_set_frequency(new_pwm->key, freq) == 0);
ASSRT(softpwm_set_polarity(new_pwm->key, polarity) == 0);
pthread_mutex_lock(new_params_lock);
// create thread for pwm
ret = pthread_create(&new_thread, NULL, softpwm_thread_toggle, (void *)new_pwm);
ASSRT(ret == 0);
new_pwm->thread = new_thread;
pthread_mutex_unlock(new_params_lock);
return 1;
}
// python method PWM.set_duty_cycle(channel, duty_cycle)
static PyObject *py_set_duty_cycle(PyObject *self, PyObject *args, PyObject *kwargs)
{
char key[8];
char *channel;
int gpio;
int allowed = -1;
float duty_cycle = 0.0;
static char *kwlist[] = {"channel", "duty_cycle", NULL};
clear_error_msg();
if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s|f", kwlist, &channel, &duty_cycle))
return NULL;
if (duty_cycle < 0.0 || duty_cycle > 100.0) {
PyErr_SetString(PyExc_ValueError, "duty_cycle must have a value from 0.0 to 100.0");
return NULL;
}
if (!get_key(channel, key)) {
PyErr_SetString(PyExc_ValueError, "Invalid PWM key or name.");
return NULL;
}
// check to ensure gpio is one of the allowed pins
// Not protecting the call as if the get_key() fails, we won't make it here
get_gpio_number(channel, &gpio);
// Check to see if GPIO is allowed on the hardware
// A 1 means we're good to go
allowed = gpio_allowed(gpio);
if (allowed == -1) {
char err[2000];
snprintf(err, sizeof(err), "Error determining hardware. (%s)", get_error_msg());
PyErr_SetString(PyExc_ValueError, err);
return NULL;
} else if (allowed == 0) {
char err[2000];
snprintf(err, sizeof(err), "GPIO %d not available on current Hardware", gpio);
PyErr_SetString(PyExc_ValueError, err);
return NULL;
}
if (softpwm_set_duty_cycle(key, duty_cycle) == -1) {
PyErr_SetString(PyExc_RuntimeError, "You must start() the PWM channel first");
return NULL;
}
Py_RETURN_NONE;
}
