artiq/artiq/coredevice/i2c.py

210 lines
5.9 KiB
Python

"""
Non-realtime drivers for I2C chips on the core device.
"""
from artiq.language.core import syscall, kernel
from artiq.language.types import TBool, TInt32, TNone
from artiq.coredevice.exceptions import I2CError
@syscall(flags={"nounwind", "nowrite"})
def i2c_start(busno: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nounwind", "nowrite"})
def i2c_restart(busno: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nounwind", "nowrite"})
def i2c_stop(busno: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nounwind", "nowrite"})
def i2c_write(busno: TInt32, b: TInt32) -> TBool:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nounwind", "nowrite"})
def i2c_read(busno: TInt32, ack: TBool) -> TInt32:
raise NotImplementedError("syscall not simulated")
@kernel
def i2c_poll(busno, busaddr):
"""Poll I2C device at address.
:param busno: I2C bus number
:param busaddr: 8 bit I2C device address (LSB=0)
:returns: True if the poll was ACKed
"""
i2c_start(busno)
ack = i2c_write(busno, busaddr)
i2c_stop(busno)
return ack
@kernel
def i2c_write_byte(busno, busaddr, data, ack=True):
"""Write one byte to a device.
:param busno: I2C bus number
:param busaddr: 8 bit I2C device address (LSB=0)
:param data: Data byte to be written
:param nack: Allow NACK
"""
i2c_start(busno)
try:
if not i2c_write(busno, busaddr):
raise I2CError("failed to ack bus address")
if not i2c_write(busno, data) and ack:
raise I2CError("failed to ack write data")
finally:
i2c_stop(busno)
@kernel
def i2c_read_byte(busno, busaddr):
"""Read one byte from a device.
:param busno: I2C bus number
:param busaddr: 8 bit I2C device address (LSB=0)
:returns: Byte read
"""
i2c_start(busno)
data = 0
try:
if not i2c_write(busno, busaddr | 1):
raise I2CError("failed to ack bus read address")
data = i2c_read(busno, ack=False)
finally:
i2c_stop(busno)
return data
@kernel
def i2c_write_many(busno, busaddr, addr, data, ack_last=True):
"""Transfer multiple bytes to a device.
:param busno: I2c bus number
:param busaddr: 8 bit I2C device address (LSB=0)
:param addr: 8 bit data address
:param data: Data bytes to be written
:param ack_last: Expect I2C ACK of the last byte written. If `False`,
the last byte may be NACKed (e.g. EEPROM full page writes).
"""
n = len(data)
i2c_start(busno)
try:
if not i2c_write(busno, busaddr):
raise I2CError("failed to ack bus address")
if not i2c_write(busno, addr):
raise I2CError("failed to ack data address")
for i in range(n):
if not i2c_write(busno, data[i]) and (
i < n - 1 or ack_last):
raise I2CError("failed to ack write data")
finally:
i2c_stop(busno)
@kernel
def i2c_read_many(busno, busaddr, addr, data):
"""Transfer multiple bytes from a device.
:param busno: I2c bus number
:param busaddr: 8 bit I2C device address (LSB=0)
:param addr: 8 bit data address
:param data: List of integers to be filled with the data read.
One entry ber byte.
"""
m = len(data)
i2c_start(busno)
try:
if not i2c_write(busno, busaddr):
raise I2CError("failed to ack bus address")
if not i2c_write(busno, addr):
raise I2CError("failed to ack data address")
i2c_restart(busno)
if not i2c_write(busno, busaddr | 1):
raise I2CError("failed to ack bus read address")
for i in range(m):
data[i] = i2c_read(busno, ack=i < m - 1)
finally:
i2c_stop(busno)
class PCA9548:
"""Driver for the PCA9548 I2C bus switch.
I2C transactions not real-time, and are performed by the CPU without
involving RTIO.
On the KC705, this chip is used for selecting the I2C buses on the two FMC
connectors. HPC=1, LPC=2.
"""
def __init__(self, dmgr, busno=0, address=0xe8, core_device="core"):
self.core = dmgr.get(core_device)
self.busno = busno
self.address = address
@kernel
def select(self, mask):
"""Enable/disable channels.
:param mask: Bit mask of enabled channels
"""
i2c_write_byte(self.busno, self.address, mask)
@kernel
def set(self, channel):
"""Enable one channel.
:param channel: channel number (0-7)
"""
self.select(1 << channel)
@kernel
def readback(self):
return i2c_read_byte(self.busno, self.address)
class TCA6424A:
"""Driver for the TCA6424A I2C I/O expander.
I2C transactions not real-time, and are performed by the CPU without
involving RTIO.
On the NIST QC2 hardware, this chip is used for switching the directions
of TTL buffers."""
def __init__(self, dmgr, busno=0, address=0x44, core_device="core"):
self.core = dmgr.get(core_device)
self.busno = busno
self.address = address
@kernel
def _write24(self, addr, value):
i2c_write_many(self.busno, self.address, addr,
[value >> 16, value >> 8, value])
@kernel
def set(self, outputs):
"""Drive all pins of the chip to the levels given by the
specified 24-bit word.
On the QC2 hardware, the LSB of the word determines the direction of
TTL0 (on a given FMC card) and the MSB that of TTL23.
A bit set to 1 means the TTL is an output.
"""
outputs_le = (
((outputs & 0xff0000) >> 16) |
(outputs & 0x00ff00) |
(outputs & 0x0000ff) << 16)
self._write24(0x8c, 0) # set all directions to output
self._write24(0x84, outputs_le) # set levels