Control GPIO, I2C and SPI on A20-OLinuXino-MICRO
The package provide methods for controlling GPIO pins, I2C and SPI buses. It’s written for A20-OLinuXino-MICRO, but it can be used with other boards. In this case proper operation is not guaranteed. You can check wiki for more information.
When using GPIO make sure that the desired gpio is not used by another periphery.
Using this library requires root access.
The following methods are available:
init() - Make initialization of the module. Must be called first.
getcfg() - Read current configuration of gpio.
setcfg() - Write configuration to gpio.
input() - Return current value of gpio.
output() - Set output value.
pullup() - Set pull-up/pull-down.
The available constants are:
HIGH - 1
LOW - 0
INPUT - 0
OUPTUT - 1
PULLUP - 1
PULLDOWN - 2
The gpio are named two ways:
By port name: PH0, PG2, PE10, etc. These can be imported from port module:
>>> from pyA20.gpio import port >>> dir(port)
By connector name and pin number: gpio2p12, gpio3p8, lcdp18, uext1p3 and etc:
>>> from pyA20.gpio import connector >>> dir(connector)
Generally these constants are just an offset in the memory from the base GPIO address, so they can be assigned to a number type variable.
>>> led = port.PH2 >>> print led 226
init() - Make initialization of the module
open() - Begin communication with slave device
read() - Read from slave device
write() - Write data to slave device
close() - End communication with slave device
open() - Open SPI bus with given configuration
read() - Read data from slave device without write
write() - Write data to slave device without read
xfer() - Do write and after that read
close() - Close SPI bus
The example consist of: * Initialize gpio module * Initialize one gpio as output and another one as input * Polling input state and write corresponding output value
#!/usr/bin/env python from pyA20.gpio import gpio from pyA20.gpio import port from pyA20.gpio import connector gpio.init() #Initialize module. Always called first gpio.setcfg(port.PG9, gpio.OUTPUT) #Configure LED1 as output gpio.setcfg(port.PG9, 1) #This is the same as above gpio.setcfg(port.PE11, gpio.INPUT) #Configure PE11 as input gpio.setcfg(port.PE11, 0) #Same as above gpio.pullup(port.PE11, 0) #Clear pullups gpio.pullup(port.PE11, gpio.PULLDOWN) #Enable pull-down gpio.pullup(port.PE11, gpio.PULLUP) #Enable pull-up while True: if gpio.input(port.PE11) == 1: gpio.output(port.PG9, gpio.LOW) gpio.output(port.PG9, 0) else: gpio.output(port.PG9, gpio.HIGH) gpio.output(port.PG9, 1)
In this example: * I2C module is imported * Bus number 2 is opened * Some data is written, then verified
#!/usr/bin/env python from pyA20 import i2c i2c.init("/dev/i2c-2") #Initialize module to use /dev/i2c-2 i2c.open(0x55) #The slave device address is 0x55 #If we want to write to some register i2c.write([0xAA, 0x20]) #Write 0x20 to register 0xAA i2c.write([0xAA, 0x10, 0x11, 0x12]) #Do continuous write with start address 0xAA #If we want to do write and read i2c.write([0xAA]) #Set address at 0xAA register value = i2c.read(1) #Read 1 byte with start address 0xAA i2c.close() #End communication with slave device
In ths example: * SPI module is imported * Bus 2 with chip-select 0 is opened * Some data is transfered to slave device
#!/usr/bin/env python from pyA20 import spi spi.open("/dev/spidev2.0") #Open SPI device with default settings # mode : 0 # speed : 100000kHz # delay : 0 # bits-per-word: 8 #Different ways to open device spi.open("/dev/spidev2.0", mode=1) spi.open("/dev/spidev2.0", mode=2, delay=0) spi.open("/dev/spidev2.0", mode=3, delay=0, bits_per_word=8) spi.open("/dev/spidev2.0", mode=0, delay=0, bits_per_word=8, speed=100000) spi.write([0x01, 0x02]) #Write 2 bytes to slave device spi.read(2) #Read 2 bytes from slave device spi.xfer([0x01, 0x02], 2) #Write 2 byte and then read 2 bytes. spi.close() #Close SPI bus
pyA20 0.2.10 (21 NOV 2017)
Removed processor checking to allow build scripts
pyA20 0.2.0 (02 SEP 2014)
Updated to enable SPI and I2C control
GPIO constant in separate modules
Added example files
Added support for Python3
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