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Control GPIO, I2C and SPI

Project description

This package provide methods for controlling GPIO pins, I2C and SPI buses. This is written for A20-OLinuXino-LIME2, but it can be used with other boards. If you do this we cannot guarantee proper operation of the module. Before using this package we recommend reading the article at olimex wiki:

https://www.olimex.com/wiki/A20-OLinuXino-LIME2

When using GPIO make sure that the desired gpio is not used by another periphery.

GPIO METHODS

init() - Make initialization of the module. Always 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:

NAME - EQUALS TO ==== ========= 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 pyA20Lime2.gpio import port
>>> dir(port)

By connector name and pin number: gpio2p12, gpio3p8, etc. These can be imported from connector module:

>>> from pyA20Lime2.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

I2C METHODS

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

SPI METHODS

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

Examples

GPIO:

#!/usr/bin/env python

from pyA20Lime2.gpio import gpio
from pyA20Lime2.gpio import port
from pyA20Lime2.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)

I2C:

#!/usr/bin/env python

from pyA20Lime2 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

SPI:

#!/usr/bin/env python

from pyA20Lime2 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

It’s important that you run your python script as root!

Changelog

  • pyAA20Lime2 0.2.1 (30 JUN 2015)
    • Fixed issue with SPI xfer function
  • pyA20Lime2 0.2.0 (3 SEP 2014)
    • Initial release

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