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ad9914: optimize extended-resolution mode

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This commit is contained in:
Sebastien Bourdeauducq 2018-05-13 23:01:06 +08:00
parent c8d91b297d
commit 663d8e66ba
1 changed files with 38 additions and 17 deletions
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55
artiq/coredevice/ad9914.py
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@ -30,8 +30,6 @@ AD9914_REG_DRGBL = 0x15
AD9914_REG_DRGBH = 0x17
AD9914_REG_DRGAL = 0x19
AD9914_REG_DRGAH = 0x1b
AD9914_REG_FTWL = 0x2d
AD9914_REG_FTWH = 0x2f
AD9914_REG_POW = 0x31
AD9914_REG_ASF = 0x33
AD9914_REG_USR0 = 0x6d
@ -71,10 +69,11 @@ class AD9914:
self.write_duration_mu = 5 * self.rtio_period_mu
self.dac_cal_duration_mu = 147000 * self.rtio_period_mu
self.init_duration_mu = 10 * self.write_duration_mu + self.dac_cal_duration_mu
self.init_sync_duration_mu = 18 * self.write_duration_mu + 2 * self.dac_cal_duration_mu
self.set_duration_mu = 6 * self.write_duration_mu
self.init_duration_mu = 13 * self.write_duration_mu + self.dac_cal_duration_mu
self.init_sync_duration_mu = 21 * self.write_duration_mu + 2 * self.dac_cal_duration_mu
self.set_duration_mu = 7 * self.write_duration_mu
self.set_x_duration_mu = 7 * self.write_duration_mu
self.exit_x_duration_mu = 3 * self.write_duration_mu
self.continuous_phase_comp = 0
@ -93,9 +92,14 @@ class AD9914:
delay_mu(-self.init_duration_mu)
self.write(AD9914_GPIO, (1 << self.channel) << 1);
# Note another undocumented "feature" of the AD9914:
# Programmable modulus breaks if the digital ramp enable bit is
# not set at the same time.
self.write(AD9914_REG_CFR1H, 0x0000) # Enable cosine output
self.write(AD9914_REG_CFR2L, 0x8900) # Enable matched latency
self.write(AD9914_REG_CFR2H, 0x0080) # Enable profile mode
self.write(AD9914_REG_CFR2H, 0x0089) # Enable profile mode + programmable modulus + DRG
self.write(AD9914_REG_DRGAL, 0) # Programmable modulus A = 0
self.write(AD9914_REG_DRGAH, 0)
self.write(AD9914_REG_DRGBH, 0x8000) # Programmable modulus B == 2**31
self.write(AD9914_REG_DRGBL, 0x0000)
self.write(AD9914_REG_ASF, 0x0fff) # Set amplitude to maximum
@ -141,7 +145,9 @@ class AD9914:
self.write(AD9914_REG_CFR4H, 0x0005) # Disable DAC calibration
self.write(AD9914_FUD, 0)
self.write(AD9914_REG_CFR1H, 0x0000) # Enable cosine output
self.write(AD9914_REG_CFR2H, 0x0080) # Enable profile mode
self.write(AD9914_REG_CFR2H, 0x0089) # Enable profile mode + programmable modulus + DRG
self.write(AD9914_REG_DRGAL, 0) # Programmable modulus A = 0
self.write(AD9914_REG_DRGAH, 0)
self.write(AD9914_REG_DRGBH, 0x8000) # Programmable modulus B == 2**31
self.write(AD9914_REG_DRGBL, 0x0000)
self.write(AD9914_REG_ASF, 0x0fff) # Set amplitude to maximum
@ -196,8 +202,8 @@ class AD9914:
self.write(AD9914_GPIO, (1 << self.channel) << 1)
self.write(AD9914_REG_FTWL, ftw & 0xffff)
self.write(AD9914_REG_FTWH, (ftw >> 16) & 0xffff)
self.write(AD9914_REG_DRGFL, ftw & 0xffff)
self.write(AD9914_REG_DRGFL, (ftw >> 16) & 0xffff)
# We need the RTIO fine timestamp clock to be phase-locked
# to DDS SYSCLK, and divided by an integer self.sysclk_per_mu.
@ -265,18 +271,22 @@ class AD9914:
self.turns_to_pow(phase), phase_mode,
self.amplitude_to_asf(amplitude))
# Extended resolution functions
# Extended-resolution functions
@kernel
def set_mu_x(self, xftw, amplitude=0x0fff):
"""Set the DDS frequency and amplitude with an extended-resolution
(63-bit) frequency tuning word.
Phase control is not implemented in this mode; the phase offset
can assume any value.
After this function has been called, exit extended-resolution mode
before calling functions that use standard-resolution mode.
"""
delay_mu(-self.set_x_duration_mu)
self.write(AD9914_GPIO, (1 << self.channel) << 1)
# Enable programmable modulus.
# Note another undocumented "feature" of the AD9914:
# Programmable modulus breaks if the digital ramp enable bit is
# not set at the same time.
self.write(AD9914_REG_CFR2H, 0x0089)
self.write(AD9914_REG_DRGAL, xftw & 0xffff)
self.write(AD9914_REG_DRGAH, (xftw >> 16) & 0x7fff)
self.write(AD9914_REG_DRGFL, (xftw >> 31) & 0xffff)
@ -285,6 +295,14 @@ class AD9914:
self.write(AD9914_FUD, 0)
@kernel
def exit_x(self):
"""Exits extended-resolution mode."""
delay_mu(-self.exit_x_duration_mu)
self.write(AD9914_GPIO, (1 << self.channel) << 1)
self.write(AD9914_REG_DRGAL, 0)
self.write(AD9914_REG_DRGAH, 0)
@portable(flags={"fast-math"})
def frequency_to_xftw(self, frequency):
"""Returns the frequency tuning word corresponding to the given
@ -301,7 +319,10 @@ class AD9914:
@kernel
def set_x(self, frequency, amplitude=1.0):
"""Like ``set_mu_x``, but uses Hz and turns."""
"""Like ``set_mu_x``, but uses Hz and turns.
Note that the precision of ``float`` is less than the precision
of the extended frequency tuning word.
"""
self.set_mu_x(self.frequency_to_xftw(frequency),
self.amplitude_to_asf(amplitude))