python-periphery

Linux Peripheral I/O (GPIO, SPI, I2C, MMIO, Serial) with Python 2 / Python 3

python-periphery is a pure Python library for GPIO, SPI, I2C, MMIO, and Serial peripheral I/O interface access in userspace Linux. It is useful in embedded Linux environments (including BeagleBone, Raspberry Pi, etc. platforms) for interfacing with external peripherals. python-periphery is compatible with Python 2 and Python 3, is written in pure Python, and is MIT licensed.

Examples

GPIO

from periphery import GPIO

# Open GPIO 10 with input direction
gpio_in = GPIO(10, "in")
# Open GPIO 12 with output direction
gpio_out = GPIO(12, "out")

value = gpio_in.read()
gpio_out.write(value)

gpio_in.close()
gpio_out.close()

SPI

from periphery import SPI

# Open spidev1.0 with mode 0 and max speed 1MHz
spi = SPI("/dev/spidev1.0", 0, 1000000)

data_out = [0xaa, 0xbb, 0xcc, 0xdd]
data_in = spi.transfer(data_out)

print("shifted out [0x%02x, 0x%02x, 0x%02x, 0x%02x]" % tuple(data_out))
print("shifted in  [0x%02x, 0x%02x, 0x%02x, 0x%02x]" % tuple(data_in))

spi.close()

I2C

from periphery import I2C

# Open i2c-0 controller
i2c = I2C("/dev/i2c-0")

# Read byte at address 0x100 of EEPROM at 0x50
msgs = [I2C.Message([0x01, 0x00]), I2C.Message([0x00], read=True)]
i2c.transfer(0x50, msgs)
print("0x100: 0x%02x" % msgs[1].data[0])

i2c.close()

MMIO

from periphery import MMIO

# Open am335x real-time clock subsystem page
rtc_mmio = MMIO(0x44E3E000, 0x1000)

# Read current time
rtc_secs = rtc_mmio.read32(0x00)
rtc_mins = rtc_mmio.read32(0x04)
rtc_hrs = rtc_mmio.read32(0x08)

print("hours: %02x minutes: %02x seconds: %02x" % (rtc_hrs, rtc_mins, rtc_secs))

rtc_mmio.close()

# Open am335x control module page
ctrl_mmio = MMIO(0x44E10000, 0x1000)

# Read MAC address
mac_id0_lo = ctrl_mmio.read32(0x630)
mac_id0_hi = ctrl_mmio.read32(0x634)

print("MAC address: %04x%08x" % (mac_id0_lo, mac_id0_hi))

ctrl_mmio.close()

Serial

from periphery import Serial

# Open /dev/ttyUSB0 with baudrate 115200, and defaults of 8N1, no flow control
serial = Serial("/dev/ttyUSB0", 115200)

serial.write(b"Hello World!")

# Read up to 128 bytes with 500ms timeout
buf = serial.read(128, 0.5)
print("read %d bytes: _%s_" % (len(buf), buf))

serial.close()

Documentation

Coming soon.

Installation

Coming soon.

Testing

The tests located in the tests folder may be run under Python to test the correctness and functionality of python-periphery. Some tests require interactive probing (e.g. with an oscilloscope), the installation of a physical loopback, or the existence of a particular device on a bus. See the usage of each test for more details on the required setup.

License

python-periphery is MIT licensed. See the included LICENSE file.