Python Programming using MRAA (SPI)

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 the SPI functionality in Kernel with loop-back test.

Required Hardware

• a5d2x-rugged board

• USB cable

• Patch cords

Step-by-step guide

• Boot the board from MMC. After booting connect the one end of patch card to MOSI pin and other end to MISO pin.

• Copy the spi.py python code in data directory of your board.

• Run the below python code.

Test spi.py

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

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

PROGRAM: spi.py

import mraa as m
import random as rand
import array

# intialise SPI
dev = m.Spi(0)

for x in range(0,100):
    txbuf = bytearray(4)
    for y in range(0,4):
        txbuf[y] = rand.randrange(0, 256)
 
# send and receive data through SPI
rxbuf = dev.write(txbuf)
if rxbuf != txbuf:
    print("Data mismatch!")
    exit(1)
print(rxbuf)

Execution :

Run the above code with below command in rugged board.

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

Expected Output

When MISO & MOSI are short.

oot@ruggedboard-a5d2x:/data# python3 spi.py libmraa[149]: libmraa version v2.0.0 initialised by user 'root' with EUID 0 libmraa[149]: gpio: platform doesn't support chardev, falling back to sysfs libmraa[149]: libmraa initialised for platform 'Atmel SAMA5' of type 20 bytearray(b'\xd1\xa2\x80\x93') bytearray(b'z:l\x11') bytearray(b'WC\xf5\xd9') bytearray(b'\xcd\tq\xeb') bytearray(b'IEs\xfa') bytearray(b'\xbf\x1b\xe2b') bytearray(b'3l\x80\xe9') bytearray(b'\x8e\xf4\x05X') bytearray(b'C\n\xb0\xa5') bytearray(b'\x8f\xf5\xfe\xa1') bytearray(b'\xf8LPi') bytearray(b'"\xd5(z') bytearray(b'\x10*F9') bytearray(b'\xaf\xbef\xe9') bytearray(b'\x80\xbd\x10C') bytearray(b'\xb6\x8e\xdc8') bytearray(b'k\xad\x96\xcc') bytearray(b'\xb8y\xael') bytearray(b'\xddwsT') bytearray(b'\x16\xfc\xcf\x9f') bytearray(b'\xddu\x0f\xf8') bytearray(b'\x05\xbd\x06\xc7') bytearray(b'yaW\x00') bytearray(b'\xe7b\xfe\xf5') bytearray(b'\xca0\xd0\xf6') bytearray(b'\xbf\xdbH\xc5') bytearray(b'Cb\xfau') bytearray(b'\xc7`c\x9e') bytearray(b'L\\xec8') bytearray(b'\x8a(\xc0\xad') bytearray(b'\xeb\x9fm~') bytearray(b'now\xc4') bytearray(b'\xc7]\x9b\xc6') bytearray(b'\x1c5W\xe7') bytearray(b'\xa9\xd2\xce\xd1') bytearray(b'\x95"\xd66') bytearray(b'h|\xb9\xb4') bytearray(b'\xff&/\xf9') bytearray(b'\x8f\xee\xc0d') bytearray(b'S=\xb5\x8b') bytearray(b'.\x94\x91\x96') bytearray(b'\x9c\xb0\x1fd') bytearray(b'\x83(\x03+') bytearray(b'\xee\xfb\x18\xde') bytearray(b'\xfb\xf8\x01\xf4') bytearray(b'[\x89_\x87') bytearray(b'|\x98\x7f\x8c') bytearray(b'n32\xe7') bytearray(b'Y\xc7\x9b\xda') bytearray(b'\xc0A\xc5p') bytearray(b'\x0e\xf5\x1e\x0f') bytearray(b'qse1') bytearray(b'5\xf5\x07\x1a') bytearray(b'\xf3\xe9y?') bytearray(b'\xcf\xc5om') bytearray(b'\x8c\xe3\x8d\xb9') bytearray(b'M9\x88\xa9') bytearray(b'\xcc\x80\x02\x1f') bytearray(b'\xee\x05\x8a\x99') bytearray(b'P8\x1ah') bytearray(b'\x9cT\xcb\xd0') bytearray(b'\xfa\x9c\xa1T') bytearray(b'\x98\x85\xca\x0b') bytearray(b'{\x0fS$') bytearray(b'\x80\x15\x9a\x1e') bytearray(b'\xd6c\xe2Q') bytearray(b'.\xc0\x14\xbf') bytearray(b'\xafV^G') bytearray(b'\x9a\xfd\x0c\x84') bytearray(b'\x8b\n\x03\x8a') bytearray(b'z\x02[\xf4') bytearray(b'\x11\xa5My') bytearray(b'r<V\xa2') bytearray(b'E\xb4\x1a\xec') bytearray(b'\xbap\x9c\xc4') bytearray(b'\xf5\x9eU\x85') bytearray(b'\x91\x8b\x014') bytearray(b'o\xf86\xcf') bytearray(b'"a>\x9b') bytearray(b'\x1e\x95\x86\x00') bytearray(b'\x16+)\t') bytearray(b'\x1f\xf7(E') bytearray(b'c\xdd\x97\xf5') bytearray(b'\x89\xbc\xfe\xb6') bytearray(b'W\xd0\x07\x01') bytearray(b'\x94?\x04Q') bytearray(b'\xf1\xfa\xcc\x17')

When MISO & MOSI are not short.

uninitialized urandom read (24 bytes read) libmraa[135]: libmraa version v2.0.0 initialised by user 'root' with EUID 0 libmraa[135]: gpio: platform doesn't support chardev, falling back to sysfs libmraa[135]: libmraa initialised for platform 'Atmel SAMA5' of type 20 random: python3: uninitialized urandom read (2500 bytes read) Data mismatch!