Source code for artiq.coredevice.pcf8574a

from artiq.experiment import kernel
from artiq.coredevice.i2c import (
    i2c_start, i2c_write, i2c_read, i2c_stop, I2CError)

[docs]class PCF8574A: """Driver for the PCF8574 I2C remote 8-bit I/O expander. I2C transactions not real-time, and are performed by the CPU without involving RTIO. """ def __init__(self, dmgr, busno=0, address=0x7c, core_device="core"): self.core = dmgr.get(core_device) self.busno = busno self.address = address
[docs] @kernel def set(self, data): """Drive data on the quasi-bidirectional pins. :param data: Pin data. High bits are weakly driven high (and thus inputs), low bits are strongly driven low. """ i2c_start(self.busno) try: if not i2c_write(self.busno, self.address): raise I2CError("PCF8574A failed to ack address") if not i2c_write(self.busno, data): raise I2CError("PCF8574A failed to ack data") finally: i2c_stop(self.busno)
[docs] @kernel def get(self): """Retrieve quasi-bidirectional pin input data. :return: Pin data """ i2c_start(self.busno) ret = 0 try: if not i2c_write(self.busno, self.address | 1): raise I2CError("PCF8574A failed to ack address") ret = i2c_read(self.busno, False) finally: i2c_stop(self.busno) return ret