Dev documentation (#369)

* Update eeprom_constants.py

* added documentation

* added special Note to the PWM readme

* suggested fix

* frequency type to float

Author: sjpark608

src/edgepi/eeprom/eeprom_constants.py

@@ -13,6 +13,57 @@
 SCg0AAIA/FQAAAAAaCg0AAIA/FQAAAAAiCg0AAIA/FQAAAAAqCg0AAIA/FQAAAAAyCg0AAIA/FQAAAAA6Cg0AAIA/FQAAAABCCg\
 0AAIA/FQAAAAA='
 
+"""
+Defaul EEPROM Dataclass
+dac_calib_params
+    dac_ch1
+        gain = 1
+        offset = 0
+    ~
+    dac_ch8
+        gain = 1
+        offset = 0
+adc1_calib_params
+    adc_ch_1
+        gain = 1
+        offset = 0
+    ~
+    adc_ch_8
+        gain = 1
+        offset = 0
+    diff1
+        gain = 1
+        offset = 0
+    ~
+    diff4
+adc2_calib_params
+    same as adc1_calib_params
+rtd_calib_params
+    rtd
+        gain = 1
+        offset = 0
+    rtd_resistor = 2000
+tc_calib_params
+    tc_B
+        gain = 1
+        offset = 0
+    ~
+    tc_T
+        gain = 1
+        offset = 0
+config_key
+    private_key = None
+    certificate = None
+data_key
+    private_key = None
+    certificate = None
+serial = None
+model = None
+cm_part_number = None
+tb_part_number = None
+cm4_part_number = None
+"""
+
 
 
 class EEPROMInfo(Enum):

src/edgepi/pwm/README.md

@@ -14,16 +14,17 @@ edgepi_pwm = EdgePiPWM()
 
 # Initialize and open pwm device
 edgepi_pwm.init_pwm(PWMPins.PWM1)
-# Setting PWM parameters
-edgepi_pwm.set_config(PWMPins.PWM1, 1000.0, 50.0)
-# enable the pwm signal 
+# Setting PWM parameters, frequency 1000.0 to 10,000.0 , duty cycle form 0-1.0
+edgepi_pwm.set_config(PWMPins.PWM1, 1000.0, 0.50)
+# enable the pwm signal, PWM duty cycle and frequency must be set to enable the singal
 edgepi_pwm.enable()
 # disable the pwm signal 
 edgepi_pwm.disable()
 # Close PWM device
 edgepi_pwm.close()
 
 ```
+__NOTE__: Frequency and duty-cycle must be set before enabling the PWM signal.
 
 # User Guide
 - Instantiating the module generate the PWM device file

src/edgepi/pwm/edgepi_pwm.py

@@ -201,7 +201,7 @@ def init_pwm(self, pwm_num: PWMPins):
         self.log.debug("init_pwm: PWM device is already open")
 
     def set_config(self, pwm_num: PWMPins,
-                   frequency: int = None,
+                   frequency: float = None,
                    duty_cycle: int = None,
                    polarity: Polarity = None
                    ):