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nix-servo/fast-servo/pyfastservo/dac.py

182 lines
5.1 KiB
Python

# This file is part of Fast Servo Software Package.
#
# Copyright (C) 2023 Jakub Matyas
# Warsaw University of Technology <jakubk.m@gmail.com>
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
import mmap
import os
import spidev
from common import (
CH0_HIGH_WORD_ADDR,
CH0_LOW_WORD_ADDR,
CH1_HIGH_WORD_ADDR,
CH1_LOW_WORD_ADDR,
CTRL_ADDR,
MAP_MASK,
PAGESIZE,
)
# /dev/spidev2.0 <=> spidev<BUS>.<DEVICE>
MAIN_DAC_BUS = 2
MAIN_DAC_DEVICE = 0
DAC_VERSION = 0x0A
def main_dac_init():
spi = spidev.SpiDev()
try:
spi.open(MAIN_DAC_BUS, MAIN_DAC_DEVICE)
spi.max_speed_hz = 5000
spi.mode = 0b00 # CPOL = 0 CPHA = 0
spi.cshigh = True
spi_buffer = [0x00, 0x10] # software reset
spi.xfer2(spi_buffer)
spi_buffer = [0x00, 0x00] # release software reset
spi.xfer2(spi_buffer)
spi_buffer = [
0x80,
0x00,
] # for some reason it is needed to read the reset address for reset to actually reset
rx_buffer = spi.xfer2(spi_buffer)
spi_buffer = [0x9F, 0x00] # hardware version
rx_buffer = spi.xfer2(spi_buffer)
if rx_buffer[1] != DAC_VERSION:
print(f"Unrecognized device: 0x{rx_buffer[1]:02X}")
print("=== Contents of spi buffer after DAC VERSION read back: ===")
print(f"0x{rx_buffer[0]:02X}{rx_buffer[1]:02X}")
spi_buffer = [0x82, 00]
rx_buffer = spi.xfer2(spi_buffer)
print(f"0x{rx_buffer[0]:02X}{rx_buffer[1]:02X}")
# set to 2's complement and I to be first of pair on data input pads
spi_buffer = [0x02, 0xB4]
rx_buffer = spi.xfer2(spi_buffer)
spi_buffer = [0x82, 00]
rx_buffer = spi.xfer2(spi_buffer)
print(f"0x{rx_buffer[0]:02X}{rx_buffer[1]:02X}")
for i in range(10):
spi_buffer = [0x94, 0x00]
rx_buffer = spi.xfer2(spi_buffer)
print(f"0x{rx_buffer[0]:02X}{rx_buffer[1]:02X}")
finally:
spi.close()
def read_from_memory(address, n_bytes):
assert n_bytes <= 4
addr = address
try:
f = os.open("/dev/mem", os.O_SYNC | os.O_RDWR)
with mmap.mmap(
f,
PAGESIZE,
mmap.MAP_SHARED,
mmap.PROT_READ | mmap.PROT_WRITE,
offset=addr & ~MAP_MASK,
) as mem:
start_addr = addr & MAP_MASK
stop_addr = start_addr + 4
# print(f"addr: 0x{addr:x}\tstart_addr: 0x{start_addr}\tstop_addr: 0x{stop_addr}")
contents = mem[start_addr:stop_addr]
read_value = list(contents)[:n_bytes]
finally:
os.close(f)
return read_value
def write_to_memory(address, value):
value_bytes = value.to_bytes(4, "little")
addr = address
try:
f = os.open("/dev/mem", os.O_SYNC | os.O_RDWR)
with mmap.mmap(
f,
PAGESIZE,
mmap.MAP_SHARED,
mmap.PROT_READ | mmap.PROT_WRITE,
offset=addr & ~MAP_MASK,
) as mem:
start_addr = addr & MAP_MASK
stop_addr = start_addr + 4
mem[start_addr:stop_addr] = value_bytes
contents = mem[start_addr:stop_addr]
finally:
os.close(f)
def manual_override(enable=True):
reg_contents = read_from_memory(CTRL_ADDR, 1)[0]
print(f"REG contents: 0b{reg_contents:03b}")
to_write = reg_contents | 0b1 if enable else reg_contents & 0b110
write_to_memory(CTRL_ADDR, to_write)
def power_down(channel, power_down=True):
assert channel in (0, 1)
bitmask = 1 << (channel + 1) & 0b111
reg_contents = read_from_memory(CTRL_ADDR, 1)[0]
value = (1 if power_down else 0) << (channel + 1)
reg_contents &= ~bitmask
to_write = reg_contents | value
write_to_memory(CTRL_ADDR, to_write)
reg_contents = read_from_memory(CTRL_ADDR, 1)[0]
print(f"REG contents: 0b{reg_contents:03b}")
def write_sample(channel, sample):
assert channel in (0, 1)
if channel == 0:
addresses = [CH0_HIGH_WORD_ADDR, CH0_LOW_WORD_ADDR]
else:
addresses = [CH1_HIGH_WORD_ADDR, CH1_LOW_WORD_ADDR]
low_word_value = sample & 0xFF
high_word_value = (sample >> 8) & 0x3F
values = [high_word_value, low_word_value]
for addr, value in zip(addresses, values):
write_to_memory(addr, value)
def write_ramp():
signal = [i for i in range(16384)]
for value in signal:
write_sample(0, value)
def main():
main_dac_init()
power_down(0, False)
power_down(1, False)
if __name__ == "__main__":
main()