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test_ad9910: relax SYNC window 

Signed-off-by: Robert Jördens <rj@quartiq.de>
This commit is contained in:
Robert Jördens 2018-11-06 17:37:48 +01:00
parent 172633c7da
commit 6c00ab57c0
1 changed files with 4 additions and 5 deletions
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9
artiq/coredevice/ad9910.py
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@ -414,7 +414,7 @@ class AD9910:
self.cpld.io_update.pulse(1*us)
@kernel
def tune_sync_delay(self, sync_delay_seed=8):
def tune_sync_delay(self, sync_delay_seed=9):
"""Find a stable SYNC_IN delay.
This method first locates the smallest SYNC_IN validity window at
@ -430,8 +430,8 @@ class AD9910:
"""
dt = 14 # 1/(f_SYSCLK*75ps) taps per SYSCLK period
max_delay = dt # 14*75ps > 1ns
max_window = dt//4 + 1 # 2*75ps*4 = 600ps high > 1ns/2
min_window = max(0, max_window - 2) # 2*75ps hold, 2*75ps setup
max_window = dt//4 + 1 # 75ps*4 = 300ps setup and hold
min_window = 1 # 1*75ps setup and hold
for window in range(max_window - min_window + 1):
window = max_window - window
for in_delay in range(max_delay):
@ -446,9 +446,8 @@ class AD9910:
# integrate SMP_ERR statistics for a few hundred cycles
# delay(10*us)
err = urukul_sta_smp_err(self.cpld.sta_read())
err = (err >> (self.chip_select - 4)) & 1
delay(40*us) # slack
if not err:
if not (err >> (self.chip_select - 4)) & 1:
window -= min_window # add margin
self.set_sync(in_delay, window)
self.clear_smp_err()