Copied over 2 new pwm functions from @streamnsight to close #46. these 2 functions are untested, which is why i'm not updating the readme at the moment.

source/c_pwm.c

@@ -47,7 +47,6 @@ SOFTWARE.
 
 // Global variables
 int pwm_initialized = 0;
-//int DEBUG = 0;
 
 // pwm devices (future chip pro use)
 struct pwm_dev
@@ -173,6 +172,66 @@ int pwm_set_frequency(const char *key, float freq) {
     return rtnval;
 }
 
+int pwm_set_period_ns(const char *key, unsigned long period_ns) {
+    int len;
+    int rtnval = -1;
+    char buffer[80];
+    struct pwm_exp *pwm;
+
+    //TODO: ADD CHECK FOR period_ns
+
+    pwm = lookup_exported_pwm(key);
+
+    if (pwm == NULL) {
+        return rtnval;
+    }
+    
+    if (pwm->enable) {
+        if (period_ns != pwm->period_ns) {
+            pwm->period_ns = period_ns;
+
+            len = snprintf(buffer, sizeof(buffer), "%lu", period_ns); BUF2SMALL(buffer);
+            ssize_t s = write(pwm->period_fd, buffer, len);  //ASSRT(s == len);
+            if (DEBUG) {
+                printf(" ** pwm_set_period_ns: pwm_initialized = %d\n", pwm_initialized);
+                printf(" ** pwm_set_period_ns: buffer: %s\n", buffer);
+                printf(" ** pwm_set_period_ns: s = %d, len = %d\n", s, len);
+            }
+            if (s != len) {
+                rtnval = -1;
+            } else {
+                rtnval = 1;
+            }
+        } else {
+            rtnval = 0;
+        }
+    } else {
+        rtnval = 0;
+    }
+
+    return rtnval;
+}
+
+int pwm_get_period_ns(const char *key, unsigned long *period_ns) {
+    int rtnval = -1;
+    struct pwm_exp *pwm;
+    
+    pwm = lookup_exported_pwm(key);
+
+    if (pwm == NULL) {
+        return rtnval;
+    }
+    
+    if (DEBUG)
+        printf(" ** pwm_get_period_ns: %lu **\n",pwm->period_ns);
+    
+    // Set period_ns to what we have in the struct
+    *period_ns = pwm->period_ns;
+    
+    rtnval = 0;
+    return rtnval;
+}
+
 int pwm_set_polarity(const char *key, int polarity) {
     int len;
     int rtnval = -1;
@@ -252,6 +311,44 @@ int pwm_set_duty_cycle(const char *key, float duty) {
     return rtnval;
 }
 
+int pwm_set_pulse_width_ns(const char *key, unsigned long pulse_width_ns) {
+    int len;
+    int rtnval = -1;
+    char buffer[80];
+    struct pwm_exp *pwm;
+
+    pwm = lookup_exported_pwm(key);
+
+    if (pwm == NULL) {
+        return rtnval;
+    }
+
+    if (pulse_width_ns < 0 || pulse_width_ns > pwm->period_ns)
+        return rtnval;
+
+    pwm->duty = pulse_width_ns / pwm->period_ns;
+    
+    if (pwm->enable) {
+        len = snprintf(buffer, sizeof(buffer), "%lu", pwm->duty); BUF2SMALL(buffer);
+        ssize_t s = write(pwm->duty_fd, buffer, len);  //ASSRT(s == len);
+        if (DEBUG) {
+            printf(" ** pwm_set_pulse_width_ns: pwm_initialized = %d\n", pwm_initialized);
+            printf(" ** pwm_set_pulse_width_ns: buffer: %s\n", buffer);
+            printf(" ** pwm_set_pulse_width_ns: s = %d, len = %d\n", s, len);
+        }
+        if (s != len) {
+            rtnval = -1;
+        } else {
+            rtnval = 1;
+        }
+    } else {
+        rtnval = 0;
+    }
+
+    return rtnval;
+       
+}
+
 int pwm_set_enable(const char *key, int enable)
 {
     int len;

source/c_pwm.h

@@ -32,6 +32,9 @@ SOFTWARE.
 int pwm_start(const char *key, float duty, float freq, int polarity);
 int pwm_disable(const char *key);
 int pwm_set_frequency(const char *key, float freq);
+int pwm_set_period_ns(const char *key, unsigned long period_ns);
+int pwm_get_period_ns(const char *key, unsigned long *period_ns);
 int pwm_set_duty_cycle(const char *key, float duty);
+int pwm_set_pulse_width_ns(const char *key, unsigned long pulse_width_ns);
 int pwm_set_enable(const char *key, int enable);
 void pwm_cleanup(void);

source/py_pwm.c

@@ -143,6 +143,45 @@ static PyObject *py_set_duty_cycle(PyObject *self, PyObject *args, PyObject *kwa
     Py_RETURN_NONE;
 }
 
+// python method PWM.set_pulse_width(channel, pulse_width_ns)
+static PyObject *py_set_pulse_width_ns(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    char key[8];
+    char *channel;
+    unsigned long pulse_width_ns = 0.0;
+    unsigned long period_ns;
+    static char *kwlist[] = {"channel", "pulse_width_ns", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s|k", kwlist, &channel, &pulse_width_ns))
+        return NULL;
+
+    if (!get_pwm_key(channel, key)) {
+        PyErr_SetString(PyExc_ValueError, "Invalid PWM key or name.");
+        return NULL;
+    }
+
+    // Get the period out of the data struct
+    int rtn = pwm_get_period_ns(key, &period_ns);
+    if (rtn == -1)
+    {
+        PyErr_SetString(PyExc_ValueError, "period unable to be obtained");
+        return NULL;
+    }
+
+	if (pulse_width_ns < 0.0 || pulse_width_ns > period_ns)
+    {
+        PyErr_SetString(PyExc_ValueError, "pulse width must have a value from 0 to period");
+        return NULL;
+    }
+
+    if (pwm_set_pulse_width_ns(key, pulse_width_ns) == -1) {
+        PyErr_SetString(PyExc_RuntimeError, "You must start() the PWM channel first");
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
 // python method PWM.set_frequency(channel, frequency)
 static PyObject *py_set_frequency(PyObject *self, PyObject *args, PyObject *kwargs)
 {
@@ -173,6 +212,35 @@ static PyObject *py_set_frequency(PyObject *self, PyObject *args, PyObject *kwar
     Py_RETURN_NONE;
 }
 
+// python method PWM.set_period_ns(channel, period_ns)
+static PyObject *py_set_period_ns(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    char key[8];
+    char *channel;
+    unsigned long period_ns = 2e6;
+    static char *kwlist[] = {"channel", "period_ns", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s|k", kwlist, &channel, &period_ns))
+        return NULL;
+
+    if (period_ns <= 0)
+    {
+        PyErr_SetString(PyExc_ValueError, "period must be greater than 0ns");
+        return NULL;
+    }
+
+    if (!get_pwm_key(channel, key)) {
+        PyErr_SetString(PyExc_ValueError, "Invalid PWM key or name.");
+        return NULL;
+    }
+
+    if (pwm_set_period_ns(key, period_ns) == -1) {
+        PyErr_SetString(PyExc_RuntimeError, "You must start() the PWM channel first");
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
 
 static const char moduledocstring[] = "Hardware PWM functionality of a CHIP using Python";
 
@@ -181,6 +249,8 @@ PyMethodDef pwm_methods[] = {
     {"stop", (PyCFunction)py_stop_channel, METH_VARARGS | METH_KEYWORDS, "Stop the PWM channel.  channel can be in the form of 'PWM0', or 'U13_18'"},
     {"set_duty_cycle", (PyCFunction)py_set_duty_cycle, METH_VARARGS, "Change the duty cycle\ndutycycle - between 0.0 and 100.0" },
     {"set_frequency", (PyCFunction)py_set_frequency, METH_VARARGS, "Change the frequency\nfrequency - frequency in Hz (freq > 0.0)" },
+    {"set_period_ns", (PyCFunction)py_set_period_ns, METH_VARARGS, "Change the period\nperiod_ns - period in nanoseconds" },
+    {"set_pulse_width_ns", (PyCFunction)py_set_pulse_width_ns, METH_VARARGS, "Change the period\npulse_width_ns - pulse width in nanoseconds" },
     {"cleanup", py_cleanup, METH_VARARGS, "Clean up by resetting all GPIO channels that have been used by this program to INPUT with no pullup/pulldown and no event detection"},
     {"toggle_debug", py_toggle_debug, METH_VARARGS, "Toggles the enabling/disabling of Debug print output"},
     {NULL, NULL, 0, NULL}