Updating the readme for PWM instructions and added a test case for PRM which hasn't been tested

README.rst

@@ -63,7 +63,18 @@ Detecting events::
 
 **PWM**::
 
-    Not implemented yet
+    import CHIP_IO.PWM as PWM
+    #PWM.start(channel, duty, freq=2000, polarity=0)
+    #duty values are valid 0 (off) to 100 (on)
+    PWM.start("PWM0", 50)
+    PWM.set_duty_cycle("PWM0", 25.5)
+    PWM.set_frequency("PWM0", 10)
+
+    PWM.stop("PWM0")
+    PWM.cleanup()
+
+    #set polarity to 1 on start:
+    PWM.start("PWM0", 50, 2000, 1)
 
 **ADC**::
 
@@ -91,4 +102,3 @@ The BeagleBone IO Python library was originally forked from the excellent MIT Li
 
 CHIP IO port by Robert Wolterman, released under the MIT License.
 Beaglebone IO Library Written by Justin Cooper, Adafruit Industries. BeagleBone IO Python library is released under the MIT License.
-

test/test_pwm_setup.py

@@ -0,0 +1,185 @@
+import pytest
+import os
+
+import CHIP_IO.PWM as PWM
+
+def teardown_module(module):
+    PWM.cleanup()
+
+class TestPwmSetup:
+    def test_start_pwm(self):
+        PWM.start("PWM0", 0)
+
+        pwm_test = '/sys/class/pwm/pwmchip0/pwm0'
+
+        assert os.path.exists(pwm_test)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        assert int(duty) == 0
+        assert int(period) == 500000
+        PWM.cleanup()
+
+    def test_start_pwm_with_polarity_one(self):
+        PWM.start("PWM0", 0, 2000, 1)
+
+        pwm_test = '/sys/class/pwm/pwmchip0/pwm0'
+
+        assert os.path.exists(pwm_test)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        polarity = open(pwm_test + '/polarity').read()
+        assert int(duty) == 0
+        assert int(period) == 500000
+        assert int(polarity) == 1
+        PWM.cleanup()
+
+    def test_start_pwm_with_polarity_default(self):
+        PWM.start("PWM0", 0, 2000, 0)
+
+        pwm_test = '/sys/class/pwm/pwmchip0/pwm0'
+
+        assert os.path.exists(pwm_test)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        polarity = open(pwm_test + '/polarity').read()
+        assert int(duty) == 0
+        assert int(period) == 500000
+        assert int(polarity) == 0
+        PWM.cleanup()
+
+    def test_start_pwm_with_polarity_zero(self):
+        PWM.start("PWM0", 0, 2000, 0)
+
+        pwm_test = '/sys/class/pwm/pwmchip0/pwm0'
+
+        assert os.path.exists(pwm_test)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        polarity = open(pwm_test + '/polarity').read()
+        assert int(duty) == 0
+        assert int(period) == 500000
+        assert int(polarity) == 0
+        PWM.cleanup()
+
+    def test_pwm_start_invalid_pwm_key(self):
+        with pytest.raises(ValueError):
+            PWM.start("P8_25", -1)
+
+    def test_pwm_start_invalid_duty_cycle_negative(self):
+        with pytest.raises(ValueError):
+            PWM.start("PWM0", -1)
+
+    def test_pwm_start_valid_duty_cycle_min(self):
+        #testing an exception isn't thrown
+        PWM.start("PWM0", 0)
+        PWM.cleanup()
+
+    def test_pwm_start_valid_duty_cycle_max(self):
+        #testing an exception isn't thrown
+        PWM.start("PWM0", 100)
+        PWM.cleanup()
+
+    def test_pwm_start_invalid_duty_cycle_high(self):
+        with pytest.raises(ValueError):
+            PWM.start("PWM0", 101)
+
+    def test_pwm_start_invalid_duty_cycle_string(self):
+        with pytest.raises(TypeError):
+            PWM.start("PWM0", "1")
+
+    def test_pwm_start_invalid_frequency_negative(self):
+        with pytest.raises(ValueError):
+            PWM.start("PWM0", 0, -1)
+
+    def test_pwm_start_invalid_frequency_string(self):
+        with pytest.raises(TypeError):
+            PWM.start("PWM0", 0, "1")
+
+    def test_pwm_start_negative_polarity(self):
+        with pytest.raises(ValueError):
+            PWM.start("PWM0", 0, 100, -1)
+
+    def test_pwm_start_invalid_positive_polarity(self):
+        with pytest.raises(ValueError):
+            PWM.start("PWM0", 0, 100, 2)
+
+    def test_pwm_start_invalid_polarity_type(self):
+        with pytest.raises(TypeError):
+            PWM.start("PWM0", 0, 100, "1")
+
+    def test_pwm_duty_modified(self):
+        PWM.start("PWM0", 0)
+
+        pwm_test = '/sys/class/pwm/pwmchip0/pwm0'
+
+        assert os.path.exists(pwm_test)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        assert int(duty) == 0
+        assert int(period) == 500000
+
+        PWM.set_duty_cycle("PWM0", 100)
+        duty = open(pwm_test + '/duty').read()
+        period = open(pwm_test + '/period').read()
+        assert int(duty) == 500000
+        assert int(period) == 500000
+        PWM.cleanup()
+
+    def test_pwm_duty_cycle_non_setup_key(self):
+        with pytest.raises(RuntimeError):
+            PWM.set_duty_cycle("PWM0", 100)
+            PWM.cleanup()
+
+    def test_pwm_duty_cycle_invalid_key(self):
+        with pytest.raises(ValueError):
+            PWM.set_duty_cycle("P9_15", 100)
+            PWM.cleanup()
+
+    def test_pwm_duty_cycle_invalid_value_high(self):
+        PWM.start("PWM0", 0)
+        with pytest.raises(ValueError):
+            PWM.set_duty_cycle("PWM0", 101)
+            PWM.cleanup()
+
+    def test_pwm_duty_cycle_invalid_value_negative(self):
+        PWM.start("PWM0", 0)
+        with pytest.raises(ValueError):
+            PWM.set_duty_cycle("PWM0", -1)
+            PWM.cleanup()
+
+    def test_pwm_duty_cycle_invalid_value_string(self):
+        PWM.start("PWM0", 0)
+        with pytest.raises(TypeError):
+            PWM.set_duty_cycle("PWM0", "a")
+            PWM.cleanup()
+
+    def test_pwm_frequency_invalid_value_negative(self):
+        PWM.start("PWM0", 0)
+        with pytest.raises(ValueError):
+            PWM.set_frequency("PWM0", -1)
+            PWM.cleanup()
+
+    def test_pwm_frequency_invalid_value_string(self):
+        PWM.start("PWM0", 0)
+        with pytest.raises(TypeError):
+            PWM.set_frequency("PWM0", "11")
+            PWM.cleanup()
+
+    def test_pwm_freq_non_setup_key(self):
+        with pytest.raises(RuntimeError):
+            PWM.set_frequency("PWM0", 100)
+            PWM.cleanup()
+
+    def test_pwm_freq_non_setup_key(self):
+        with pytest.raises(ValueError):
+            PWM.set_frequency("P9_15", 100)
+            PWM.cleanup()
+
+    def test_stop_pwm(self):
+        pass
+        #PWM.start("PWM0", 1)
+        #PWM.stop("PWM0")
+        #assert os.path.exists('/sys/class/gpio/gpio68')
+        #direction = open('/sys/class/gpio/gpio68/direction').read()
+        #assert direction == 'out\n'
+        #PWM.cleanup()