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.i2c 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.spi 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 0.2.12 (8 DEC 2017)
- Fixed extensions import
- Update examples
pyA20 0.2.11 (21 NOV 2017)
- Fixed mapping on portG
- Updated README
- Removed processor checking to allow build scripts
- Update license
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
Release history Release notifications | RSS feed
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.