Python Programming using MRAA (PWM)

1. Targeted Hardware

SOM Version: PICM-001-A1

CB : RuggedBoard-A5D2X

CB Version : RB-A5D2X-V1.1

1. Targeted Software

BSP-Yocto-A5D2X 2019-03-13

• AT91Bootstrap-3.8.12

• Linux Kernel v4.9.151

• uboot-2018-07

• Yocto 2.5.2 (sumo HEAD commit 623b77885051)

Description

• To test pwm with using of mraa python programming on a5d2x-Rugged board.

Required Hardware

• a5d2x-rugged board

• USB cable

• External LED

Step-by-step guide

• Boot the board from NOR/MMC.

• Please connect the positive pin of LED to the 16th pin of the M1 connector & connect the other pin of led to ground pin number 8 of the same M1 connector.

• Copy the pwm.py python file in data directory of your board.

Test pwm.py

• Open pwm.py program given below in your board terminal.

• Open the pwm.py program in /data directory.

PROGRAM: pwm.py

import mraa
import time

# initialise PWM
x = mraa.Pwm(72)
 
# set PWM period
x.period_us(700)
 
# enable PWM
x.enable(True)

value= 0.0
 
while True:

# write PWM value
x.write(value)

time.sleep(0.05)

value = value + 0.01
if value >= 1:
    value = 0.0

Execution :

Run the above code with below command in rugged board.

root@ruggedboard-a5d2x:/data# python3 pwm.py

Expected Output

root@ruggedboard-a5d2x:/data# python3 pwm.py random: python3: uninitialized urandom read (24 bytes read) libmraa[125]: libmraa version v2.0.0 initialised by user 'root' with EUID 0 libmraa[125]: gpio: platform doesn't support chardev, falling back to sysfs libmraa[125]: libmraa initialised for platform 'Atmel SAMA5' of type 20 0.010000 0.020000 0.030000 0.040000 0.049995 0.059995 0.069995 0.079995 0.089995 0.099995 0.109995 0.119995 0.129995 0.139995 0.149995 0.160000 0.170000 0.180000 0.190000 0.200000 0.210000 0.220000