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spi: add coredevice support

This commit is contained in:
Robert Jördens 2016-02-29 00:38:50 +01:00
parent d63a63531a
commit 8b2b278457
1 changed files with 88 additions and 0 deletions

88
artiq/coredevice/spi.py Normal file
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from artiq.language.core import *
from artiq.language.types import *
@syscall
def spi_write(time_mu: TInt64, channel: TInt32, addr: TInt32, data: TInt32
) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall
def spi_read(time_mu: TInt64, channel: TInt32, addr: TInt32) -> TInt32:
raise NotImplementedError("syscall not simulated")
SPI_DATA_ADDR, SPI_XFER_ADDR, SPI_CONFIG_ADDR = range(3)
(
SPI_OFFLINE,
SPI_ACTIVE,
SPI_PENDING,
SPI_CS_POLARITY,
SPI_CLK_POLARITY,
SPI_CLK_PHASE,
SPI_LSB_FIRST,
SPI_HALF_DUPLEX,
) = (1 << i for i in range(8))
class SPIMaster:
"""Core device Serial Peripheral Interface (SPI) bus master.
:param ref_period: clock period of the SPI core.
:param channel: channel number of the SPI bus to control.
"""
def __init__(self, dmgr, ref_period, channel):
self.core = dmgr.get("core")
self.ref_period_mu = int(seconds_to_mu(ref_period, self.core), 64)
self.channel = channel
self.write_div = 0
self.read_div = 0
# a full transfer takes prep_mu + xfer_mu
self.prep_mu = int(0, 64)
# chaned transfers can happen every xfer_mu
self.xfer_mu = int(0, 64)
# The second transfer of a chain be written ref_period_mu
# after the first. Read data is available every xfer_mu starting
# a bit before prep_mu + xfer_mu.
@portable
def predict_xfer_mu(self, write_length, read_length):
# this is only the intrinsic bit cycle duration
return self.ref_period_mu*(
write_length*self.write_div +
read_length*self.read_div)
@portable
def predict_prep_mu(self, write_div):
return self.ref_period_mu*(
2 + # intermediate transfers
# one write_div for the wait+idle cycle
self.write_div)
@kernel
def set_config(self, flags=0, write_div=6, read_div=6):
self.write_div = write_div
self.read_div = read_div
self.prep_mu = self.predict_prep_mu(write_div)
spi_write(now_mu(), self.channel, SPI_CONFIG_ADDR, flags |
((write_div - 2) << 8) | ((read_div - 2) << 20))
delay_mu(self.ref_period_mu)
@kernel
def set_xfer(self, chip_select=0, write_length=0, read_length=0):
self.xfer_mu = self.predict_xfer_mu(write_length, read_length)
spi_write(now_mu(), self.channel, SPI_XFER_ADDR,
chip_select | (write_length << 16) | (read_length << 24))
delay_mu(self.ref_period_mu)
@kernel
def write(self, data):
spi_write(now_mu(), self.channel, SPI_DATA_ADDR, data)
delay_mu(self.prep_mu + self.xfer_mu)
@kernel
def read(self):
r = spi_read(now_mu(), self.channel, SPI_DATA_ADDR)
delay_mu(self.ref_period_mu)
return r