Example Code for Python-Direct Control

When connecting this board to a PC via a USB cable, you can not only directly control it on PC, but also program in Python on multiple platforms like Windows, MAC, Linux, etc. to control motor or LED strip.

Software Preparation

• Windows platform: Install Python3.5+ (recommended newest version).
• Linux platform (Raspberry Pi): Most have pre-installed Python3, if not, install Python3.5+.
• Install required library and modbus: Run commands pip3 install serial and pip3 install modbus_tk.

Sample Code

The program provides the basic controllable commands. You can select your program control method and coding platform, etc, as your actual needs.

# -*- coding: utf-8 -*-
'''
PWM frequency higher than 2K, there may be relatively large difference between the frequency and the set value. 
For frequency higher than 2K, please refer to the following frequency value: 
46875HZ, 23437HZ, 15625HZ, 11718HZ,
9375HZ, 7812HZ, 6696HZ, 5859HZ, 5208HZ, 4687HZ, 4261HZ,
3906HZ, 3605HZ, 3348HZ, 3125HZ,
2929HZ, 2757HZ, 2604HZ, 2467HZ, 2343HZ, 2232HZ, 2130HZ, 2038HZ,
'''

import time
import serial
import modbus_tk
import modbus_tk.defines as cst
from modbus_tk import modbus_rtu

PORT="COM12" #Windows platform
#PORT="/dev/ttyUSB0" #Linux platform
BAUDRATE=9600
SLAVE_ADDR=0x32

PID_REG       =  0x00
VID_REG       =  0x01
ADDR_REG      =  0x02
VER_REG       =  0x05
DUTY_REG      =  0x06
FREQ_REG      =  0x07
PWM_EN_REG    =  0x08

ser = serial.Serial(port=PORT,baudrate=BAUDRATE, bytesize=8, parity='N', stopbits=1)
master = modbus_rtu.RtuMaster(ser)
time.sleep(0.5)

def get_pid():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, PID_REG, 1)
  time.sleep(0.03)
  return data[0]

def get_vid():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, VID_REG, 1)
  time.sleep(0.03)
  return data[0]

def get_addr():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, ADDR_REG, 1)
  time.sleep(0.03)
  return data[0]

def get_version():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, VER_REG, 1)
  time.sleep(0.03)
  return data[0]

def get_duty():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, DUTY_REG, 1)
  time.sleep(0.03)
  return data[0]/255

def get_freq():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, FREQ_REG, 1)
  time.sleep(0.03)
  return int(12*1000*1000/256/(data[0]+1))

def get_enable():
  data = master.execute(SLAVE_ADDR, cst.READ_HOLDING_REGISTERS, PWM_EN_REG, 1)
  time.sleep(0.03)
  return data[0]

def set_duty(duty):
  master.execute(SLAVE_ADDR, cst.WRITE_SINGLE_REGISTER, DUTY_REG, output_value=int(duty*255))
  time.sleep(0.03)

def set_freq(freq):
  master.execute(SLAVE_ADDR, cst.WRITE_SINGLE_REGISTER, FREQ_REG, output_value=int(12*1000*1000/256/freq) - 1)
  time.sleep(0.03)

def set_enable(enable):
  master.execute(SLAVE_ADDR, cst.WRITE_SINGLE_REGISTER, PWM_EN_REG, output_value=enable)
  time.sleep(0.03)

def pwm(freq, duty):
  v=[]
  v.append(int(duty*255))
  v.append(int(12*1000*1000/256/freq) - 1)
  master.execute(SLAVE_ADDR, cst.WRITE_MULTIPLE_REGISTERS, DUTY_REG, output_value=v)
  time.sleep(0.03)


print("version=0x{:x}, addr=0x{:x}".format(get_version(), get_addr()))
print("pid=0x{:x}, vid=0x{:x}".format(get_vid(), get_pid()))

print("\n--------Initial Value------") 
print("freq={}, duty={:.2f} enable={}".format(get_freq(), get_duty(), get_enable()))  

print("--------Set a new value------")  
#pwm(freq=860,duty=0.82) # freq(183HZ-46875HZ) duty(0%-100%)
set_freq(860) #(183HZ-46875HZ)
set_duty(0.82)#(0%-100%)
set_enable(1)
print("freq={}, duty={:.2f} enable={}".format(get_freq(), get_duty(), get_enable()))

print("--------Restore to factory settings(366HZ, duty ratio 50%, diable output)-------\n")
pwm(freq=366, duty=0.5) # freq(183HZ-46875HZ) duty(0%-100%)
set_enable(0)