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394 lines
15 KiB
Python
394 lines
15 KiB
Python
""""RTIO driver for the Analog Devices AD53[67][0123] family of multi-channel
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Digital to Analog Converters.
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Output event replacement is not supported and issuing commands at the same
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time is an error.
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"""
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# Designed from the data sheets and somewhat after the linux kernel
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# iio driver.
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from numpy import int32
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from artiq.language.core import (kernel, portable, delay_mu, delay, now_mu,
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at_mu)
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from artiq.language.units import ns, us
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from artiq.coredevice import spi2 as spi
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SPI_AD53XX_CONFIG = (0*spi.SPI_OFFLINE | 1*spi.SPI_END |
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0*spi.SPI_INPUT | 0*spi.SPI_CS_POLARITY |
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0*spi.SPI_CLK_POLARITY | 1*spi.SPI_CLK_PHASE |
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0*spi.SPI_LSB_FIRST | 0*spi.SPI_HALF_DUPLEX)
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AD53XX_CMD_DATA = 3 << 22
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AD53XX_CMD_OFFSET = 2 << 22
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AD53XX_CMD_GAIN = 1 << 22
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AD53XX_CMD_SPECIAL = 0 << 22
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AD53XX_SPECIAL_NOP = 0 << 16
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AD53XX_SPECIAL_CONTROL = 1 << 16
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AD53XX_SPECIAL_OFS0 = 2 << 16
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AD53XX_SPECIAL_OFS1 = 3 << 16
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AD53XX_SPECIAL_READ = 5 << 16
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AD53XX_SPECIAL_AB0 = 6 << 16
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AD53XX_SPECIAL_AB1 = 7 << 16
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AD53XX_SPECIAL_AB2 = 8 << 16
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AD53XX_SPECIAL_AB3 = 9 << 16
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AD53XX_SPECIAL_AB = 11 << 16
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# incorporate the channel offset (8, table 17) here
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AD53XX_READ_X1A = 0x008 << 7
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AD53XX_READ_X1B = 0x048 << 7
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AD53XX_READ_OFFSET = 0x088 << 7
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AD53XX_READ_GAIN = 0x0C8 << 7
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AD53XX_READ_CONTROL = 0x101 << 7
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AD53XX_READ_OFS0 = 0x102 << 7
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AD53XX_READ_OFS1 = 0x103 << 7
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AD53XX_READ_AB0 = 0x106 << 7
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AD53XX_READ_AB1 = 0x107 << 7
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AD53XX_READ_AB2 = 0x108 << 7
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AD53XX_READ_AB3 = 0x109 << 7
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@portable
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def ad53xx_cmd_write_ch(channel, value, op):
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"""Returns the word that must be written to the DAC to set a DAC
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channel register to a given value.
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:param channel: DAC channel to write to (8 bits)
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:param value: 16-bit value to write to the register
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:param op: The channel register to write to, one of
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:const:`AD53XX_CMD_DATA`, :const:`AD53XX_CMD_OFFSET` or
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:const:`AD53XX_CMD_GAIN`.
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:return: The 24-bit word to be written to the DAC
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"""
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return op | (channel + 8) << 16 | (value & 0xffff)
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@portable
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def ad53xx_cmd_read_ch(channel, op):
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"""Returns the word that must be written to the DAC to read a given
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DAC channel register.
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:param channel: DAC channel to read (8 bits)
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:param op: The channel register to read, one of
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:const:`AD53XX_READ_X1A`, :const:`AD53XX_READ_X1B`,
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:const:`AD53XX_READ_OFFSET`, :const:`AD53XX_READ_GAIN` etc.
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:return: The 24-bit word to be written to the DAC to initiate read
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"""
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return AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_READ | (op + (channel << 7))
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# maintain function definition for backward compatibility
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@portable
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def voltage_to_mu(voltage, offset_dacs=0x2000, vref=5.):
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"""Returns the 16-bit DAC register value required to produce a given output
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voltage, assuming offset and gain errors have been trimmed out.
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The 16-bit register value may also be used with 14-bit DACs. The additional
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bits are disregarded by 14-bit DACs.
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Also used to return offset register value required to produce a given
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voltage when the DAC register is set to mid-scale.
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An offset of V can be used to trim out a DAC offset error of -V.
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:param voltage: Voltage in SI units.
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Valid voltages are: [-2*vref, + 2*vref - 1 LSB] + voltage offset.
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:param offset_dacs: Register value for the two offset DACs
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(default: 0x2000)
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:param vref: DAC reference voltage (default: 5.)
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:return: The 16-bit DAC register value
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"""
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code = int(round((1 << 16) * (voltage / (4. * vref)) + offset_dacs * 0x4))
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if code < 0x0 or code > 0xffff:
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raise ValueError("Invalid DAC voltage!")
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return code
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class _DummyTTL:
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@portable
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def on(self):
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pass
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@portable
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def off(self):
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pass
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class AD53xx:
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"""Analog devices AD53[67][0123] family of multi-channel Digital to Analog
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Converters.
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:param spi_device: SPI bus device name
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:param ldac_device: LDAC RTIO TTLOut channel name (optional)
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:param clr_device: CLR RTIO TTLOut channel name (optional)
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:param chip_select: Value to drive on SPI chip select lines during
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transactions (default: 1)
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:param div_write: SPI clock divider for write operations (default: 4,
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50MHz max SPI clock with {t_high, t_low} >=8ns)
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:param div_read: SPI clock divider for read operations (default: 8, not
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optimized for speed, but cf data sheet t22: 25ns min SCLK edge to SDO
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valid)
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:param vref: DAC reference voltage (default: 5.)
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:param offset_dacs: Initial register value for the two offset DACs, device
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dependent and must be set correctly for correct voltage to mu
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conversions. Knowledge of his state is not transferred between
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experiments. (default: 8192)
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:param core_device: Core device name (default: "core")
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"""
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kernel_invariants = {"bus", "ldac", "clr", "chip_select", "div_write",
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"div_read", "vref", "core"}
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def __init__(self, dmgr, spi_device, ldac_device=None, clr_device=None,
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chip_select=1, div_write=4, div_read=16, vref=5.,
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offset_dacs=8192, core="core"):
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self.bus = dmgr.get(spi_device)
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self.bus.update_xfer_duration_mu(div_write, 24)
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if ldac_device is None:
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self.ldac = _DummyTTL()
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else:
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self.ldac = dmgr.get(ldac_device)
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if clr_device is None:
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self.clr = _DummyTTL()
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else:
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self.clr = dmgr.get(clr_device)
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self.chip_select = chip_select
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self.div_write = div_write
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self.div_read = div_read
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self.vref = vref
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self.offset_dacs = offset_dacs
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self.core = dmgr.get(core)
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@kernel
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def init(self, blind=False):
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"""Configures the SPI bus, drives LDAC and CLR high, programmes
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the offset DACs, and enables overtemperature shutdown.
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This method must be called before any other method at start-up or if
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the SPI bus has been accessed by another device.
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:param blind: If ``True``, do not attempt to read back control register
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or check for overtemperature.
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"""
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self.ldac.on()
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self.clr.on()
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self.bus.set_config_mu(SPI_AD53XX_CONFIG, 24, self.div_write,
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self.chip_select)
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self.write_offset_dacs_mu(self.offset_dacs)
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if not blind:
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ctrl = self.read_reg(channel=0, op=AD53XX_READ_CONTROL)
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if ctrl == 0xffff:
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raise ValueError("DAC not found")
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if ctrl & 0b10000:
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raise ValueError("DAC over temperature")
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delay(25*us)
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self.bus.write( # enable power and overtemperature shutdown
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(AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_CONTROL | 0b0010) << 8)
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if not blind:
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ctrl = self.read_reg(channel=0, op=AD53XX_READ_CONTROL)
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if (ctrl & 0b10111) != 0b00010:
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raise ValueError("DAC CONTROL readback mismatch")
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delay(15*us)
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@kernel
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def read_reg(self, channel=0, op=AD53XX_READ_X1A):
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"""Read a DAC register.
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This method advances the timeline by the duration of two SPI transfers
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plus two RTIO coarse cycles plus 270 ns and consumes all slack.
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:param channel: Channel number to read from (default: 0)
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:param op: Operation to perform, one of :const:`AD53XX_READ_X1A`,
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:const:`AD53XX_READ_X1B`, :const:`AD53XX_READ_OFFSET`,
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:const:`AD53XX_READ_GAIN` etc. (default: :const:`AD53XX_READ_X1A`).
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:return: The 16 bit register value
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"""
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self.bus.write(ad53xx_cmd_read_ch(channel, op) << 8)
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self.bus.set_config_mu(SPI_AD53XX_CONFIG | spi.SPI_INPUT, 24,
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self.div_read, self.chip_select)
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delay(270*ns) # t_21 min sync high in readback
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self.bus.write((AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_NOP) << 8)
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self.bus.set_config_mu(SPI_AD53XX_CONFIG, 24, self.div_write,
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self.chip_select)
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# FIXME: the int32 should not be needed to resolve unification
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return self.bus.read() & int32(0xffff)
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@kernel
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def write_offset_dacs_mu(self, value):
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"""Program the OFS0 and OFS1 offset DAC registers.
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Writes to the offset DACs take effect immediately without requiring
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a LDAC. This method advances the timeline by the duration of two SPI
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transfers.
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:param value: Value to set both offset DAC registers to
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"""
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value &= 0x3fff
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self.offset_dacs = value
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self.bus.write((AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_OFS0 | value) << 8)
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self.bus.write((AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_OFS1 | value) << 8)
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@kernel
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def write_gain_mu(self, channel, gain=0xffff):
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"""Program the gain register for a DAC channel.
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The DAC output is not updated until LDAC is pulsed (see :meth load:).
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This method advances the timeline by the duration of one SPI transfer.
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:param gain: 16-bit gain register value (default: 0xffff)
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"""
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self.bus.write(
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ad53xx_cmd_write_ch(channel, gain, AD53XX_CMD_GAIN) << 8)
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@kernel
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def write_offset_mu(self, channel, offset=0x8000):
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"""Program the offset register for a DAC channel.
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The DAC output is not updated until LDAC is pulsed (see :meth load:).
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This method advances the timeline by the duration of one SPI transfer.
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:param offset: 16-bit offset register value (default: 0x8000)
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"""
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self.bus.write(
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ad53xx_cmd_write_ch(channel, offset, AD53XX_CMD_OFFSET) << 8)
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@kernel
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def write_offset(self, channel, voltage):
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"""Program the DAC offset voltage for a channel.
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An offset of +V can be used to trim out a DAC offset error of -V.
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The DAC output is not updated until LDAC is pulsed (see :meth load:).
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This method advances the timeline by the duration of one SPI transfer.
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:param voltage: the offset voltage
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"""
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self.write_offset_mu(channel, voltage_to_mu(voltage, self.offset_dacs,
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self.vref))
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@kernel
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def write_dac_mu(self, channel, value):
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"""Program the DAC input register for a channel.
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The DAC output is not updated until LDAC is pulsed (see :meth load:).
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This method advances the timeline by the duration of one SPI transfer.
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"""
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self.bus.write(
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ad53xx_cmd_write_ch(channel, value, AD53XX_CMD_DATA) << 8)
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@kernel
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def write_dac(self, channel, voltage):
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"""Program the DAC output voltage for a channel.
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The DAC output is not updated until LDAC is pulsed (see :meth load:).
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This method advances the timeline by the duration of one SPI transfer.
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"""
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self.write_dac_mu(channel, voltage_to_mu(voltage, self.offset_dacs,
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self.vref))
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@kernel
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def load(self):
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"""Pulse the LDAC line.
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Note that there is a <= 1.5us "BUSY" period (t10) after writing to a
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DAC input/gain/offset register. All DAC registers may be programmed
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normally during the busy period, however LDACs during the busy period
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cause the DAC output to change *after* the BUSY period has completed,
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instead of the usual immediate update on LDAC behaviour.
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This method advances the timeline by two RTIO clock periods.
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"""
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self.ldac.off()
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delay_mu(2*self.bus.ref_period_mu) # t13 = 10ns ldac pulse width low
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self.ldac.on()
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@kernel
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def set_dac_mu(self, values, channels=list(range(40))):
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"""Program multiple DAC channels and pulse LDAC to update the DAC
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outputs.
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This method does not advance the timeline; write events are scheduled
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in the past. The DACs will synchronously start changing their output
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levels `now`.
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If no LDAC device was defined, the LDAC pulse is skipped.
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See :meth load:.
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:param values: list of DAC values to program
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:param channels: list of DAC channels to program. If not specified,
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we program the DAC channels sequentially, starting at 0.
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"""
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t0 = now_mu()
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# t10: max busy period after writing to DAC registers
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t_10 = self.core.seconds_to_mu(1500*ns)
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# compensate all delays that will be applied
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delay_mu(-t_10-len(values)*self.bus.xfer_duration_mu)
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for i in range(len(values)):
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self.write_dac_mu(channels[i], values[i])
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delay_mu(t_10)
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self.load()
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at_mu(t0)
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@kernel
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def set_dac(self, voltages, channels=list(range(40))):
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"""Program multiple DAC channels and pulse LDAC to update the DAC
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outputs.
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This method does not advance the timeline; write events are scheduled
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in the past. The DACs will synchronously start changing their output
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levels `now`.
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If no LDAC device was defined, the LDAC pulse is skipped.
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:param voltages: list of voltages to program the DAC channels to
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:param channels: list of DAC channels to program. If not specified,
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we program the DAC channels sequentially, starting at 0.
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"""
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values = [voltage_to_mu(voltage, self.offset_dacs, self.vref)
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for voltage in voltages]
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self.set_dac_mu(values, channels)
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@kernel
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def calibrate(self, channel, vzs, vfs):
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""" Two-point calibration of a DAC channel.
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Programs the offset and gain register to trim out DAC errors. Does not
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take effect until LDAC is pulsed (see :meth load:).
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Calibration consists of measuring the DAC output voltage for a channel
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with the DAC set to zero-scale (0x0000) and full-scale (0xffff).
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Note that only negative offsets and full-scale errors (DAC gain too
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high) can be calibrated in this fashion.
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:param channel: The number of the calibrated channel
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:params vzs: Measured voltage with the DAC set to zero-scale (0x0000)
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:params vfs: Measured voltage with the DAC set to full-scale (0xffff)
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"""
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offset_err = voltage_to_mu(vzs, self.offset_dacs, self.vref)
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gain_err = voltage_to_mu(vfs, self.offset_dacs, self.vref) - (
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offset_err + 0xffff)
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assert offset_err <= 0
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assert gain_err >= 0
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self.core.break_realtime()
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self.write_offset_mu(channel, 0x8000-offset_err)
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self.write_gain_mu(channel, 0xffff-gain_err)
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@portable
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def voltage_to_mu(self, voltage):
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"""Returns the 16-bit DAC register value required to produce a given
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output voltage, assuming offset and gain errors have been trimmed out.
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The 16-bit register value may also be used with 14-bit DACs. The
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additional bits are disregarded by 14-bit DACs.
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:param voltage: Voltage in SI units.
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Valid voltages are: [-2*vref, + 2*vref - 1 LSB] + voltage offset.
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:return: The 16-bit DAC register value
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"""
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return voltage_to_mu(voltage, self.offset_dacs, self.vref)
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