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

import mmap
import os
import logging
import time

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

import spidev
from pyfastservo.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 spi_write(spi, address, value):
    spi.xfer2([address, value])

def spi_read(spi, address):
    rx_buffer = spi.xfer2([0x80 | address, 0x00])
    return rx_buffer[1]

def hard_reset(spi):
    spi_write(spi, 0x00, 0x10)  # Software reset
    spi_write(spi, 0x00, 0x00)  # Release software reset
    spi_read(spi, 0x00)         # Read reset address (necessary for reset to take effect)

def check_version(spi):
    version = spi_read(spi, 0x1F)
    if version == DAC_VERSION:
        print(f"Verified DAC version: 0x{version:02X}")
    else:
        print(f"Unrecognized device version: 0x{version:02X}")

def set_data_control_and_output_mode(spi, mode='differential'):
    try:
        current_reg = spi_read(spi, 0x02)
        logger.info(f"Current data control register value: 0x{current_reg:02X}")

        new_reg = 0xB4

        if mode == 'differential':
            new_reg &= ~0x03
        elif mode == 'single_ended':
            new_reg = (new_reg & ~0x01) | 0x02
        else:
            logger.error(f"Invalid output mode: {mode}")
            return

        spi_write(spi, 0x02, new_reg)

        verify_reg = spi_read(spi, 0x02)
        if verify_reg == new_reg:
            logger.info(f"Data control set and output mode successfully set to {mode}")
            logger.info(f"New data control register value: 0x{verify_reg:02X}")
        else:
            logger.error(f"Failed to set data control and output mode. Expected: 0x{new_reg:02X}, Got: 0x{verify_reg:02X}")
    except Exception as e:
        logger.error(f"Error setting data control and output mode: {e}")


def wait_for_clock_sync(spi):
    max_attempts = 10
    for attempt in range(max_attempts):
        clkmode = spi_read(spi, 0x14)
        if not clkmode & 0x10:
            print(f"Clock synchronized after {attempt + 1} attempts")
            break
        if attempt == max_attempts - 1:
            print("Warning: Clock synchronization not achieved")
        time.sleep(0.001)


def enable_dac_outputs(spi):
    try:
        # Read current power-down register value
        power_down_reg = spi_read(spi, 0x01)
        logger.info(f"Current power-down register value: 0x{power_down_reg:02X}")

        if not (power_down_reg & ((1 << 4) | (1 << 3))):
            logger.info("DAC outputs are already enabled")
            return

        new_power_down_reg = power_down_reg & ~((1 << 4) | (1 << 3))
        spi_write(spi, 0x01, new_power_down_reg)

        # Verify the write operation
        verify_power_down_reg = spi_read(spi, 0x01)
        if verify_power_down_reg == new_power_down_reg:
            logger.info("DAC outputs successfully enabled")
        else:
            logger.error(f"Failed to enable DAC outputs. Expected: 0x{new_power_down_reg:02X}, Got: 0x{verify_power_down_reg:02X}")
    except Exception as e:
        logger.error(f"Error enabling DAC outputs: {e}")


def set_dac_constant_output(value=0xFFFF):
    try:
        max_value = 0x3FFF  # 14-bit maximum (2^14 - 1)
        value = min(value, max_value)
        
        # Split the value into high and low words
        low_word_value = value & 0xFF
        high_word_value = (value >> 8) & 0x3F
        
        # Write to Channel 0
        write_to_memory(CH0_HIGH_WORD_ADDR, high_word_value)
        write_to_memory(CH0_LOW_WORD_ADDR, low_word_value)
        
        # Write to Channel 1
        write_to_memory(CH1_HIGH_WORD_ADDR, high_word_value)
        write_to_memory(CH1_LOW_WORD_ADDR, low_word_value)
        
        logger.info(f"DAC outputs set to constant value: 0x{value:04X}")
        logger.info("Please verify the output using an oscilloscope")
        
    except Exception as e:
        logger.error(f"Error setting DAC constant output: {e}")


def configure_dac_for_hardware(spi):
    try:
        # Enable internal reference
        power_down_reg = spi_read(spi, 0x01)
        power_down_reg &= ~(1 << 0)  # Clear EXTREF bit for internal reference
        spi_write(spi, 0x01, power_down_reg)
        logger.info("Internal reference enabled")

        # Set RREF to default 10 kΩ for 1.0V reference
        spi_write(spi, 0x0D, 0x00)
        logger.info("RREF set to 10 kΩ for 1.0V reference")

        # Enable on-chip IRSET and QRSET
        irset_value = 0xA0                  # 10100000
        spi_write(spi, 0x04, irset_value)   # IRSET
        spi_write(spi, 0x07, irset_value)   # QRSET

        # Disable internal termination resistors
        ircml_value = 0x00
        spi_write(spi, 0x05, ircml_value)  # IRCML
        spi_write(spi, 0x08, ircml_value)  # QRCML

        spi_write(spi, 0x02, 0xB4)

        # Verify settings
        irset_read = spi_read(spi, 0x04)
        qrset_read = spi_read(spi, 0x07)
        ircml_read = spi_read(spi, 0x05)
        qrcml_read = spi_read(spi, 0x08)
        data_control_read = spi_read(spi, 0x02)
        
        if (irset_read == irset_value and qrset_read == irset_value and
            ircml_read == ircml_value and qrcml_read == ircml_value and
            data_control_read == 0xB4):
            logger.info("DAC configured for 20mA output with external termination")
        else:
            logger.error(f"DAC configuration failed. IRSET: 0x{irset_read:02X}, QRSET: 0x{qrset_read:02X}, "
                         f"IRCML: 0x{ircml_read:02X}, QRCML: 0x{qrcml_read:02X}, "
                         f"Data Control: 0x{data_control_read:02X}")

    except Exception as e:
        logger.error(f"Error configuring DAC: {e}")

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 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 = False

        hard_reset(spi)
        check_version(spi)

        configure_dac_for_hardware(spi)
        set_data_control_and_output_mode(spi, 'differential')
        wait_for_clock_sync(spi)
        enable_dac_outputs(spi)

        power_down(0, False)
        power_down(1, False)

        manual_override(True)

        set_dac_constant_output(0x1FFF)

        # Verify control register
        reg_contents = read_from_memory(CTRL_ADDR, 1)[0]
        logger.info(f"Control register contents after setting: 0b{reg_contents:03b}")

        # Verify channel settings
        ch0_high = read_from_memory(CH0_HIGH_WORD_ADDR, 1)[0]
        ch0_low = read_from_memory(CH0_LOW_WORD_ADDR, 1)[0]
        ch1_high = read_from_memory(CH1_HIGH_WORD_ADDR, 1)[0]
        ch1_low = read_from_memory(CH1_LOW_WORD_ADDR, 1)[0]
        logger.info(f"Channel 0: 0x{ch0_high:02X}{ch0_low:02X}, Channel 1: 0x{ch1_high:02X}{ch1_low:02X}")
    except Exception as e:
        print(f"Error initializing DAC: {e}")

    finally:
        spi.close()


def main():
    main_dac_init()
    
if __name__ == "__main__":
    main()