I am working on using external trigger to trigger DAQ2 TX and RX in sync. I have modified the HDL design to enable External Sync, link to the change I made https://github.com/analogdevicesinc/hdl/compare/main...jerryxuqwq:hdl:main.
I can successfully arm and trigger both RX and TX at the same time by using a external signal, observed using "iio_attr -d axi-ad9680-hpc sync_start_enable". The delay of RX is constant.
However, the delay between the trigger signal and the TX signal is not constant when measured by external scope.
1. Do I need to sync the TX DMA?
2. Is the TX initialized by the hardware trigger or software?
3. Is there a way to reliability trigger TX using external trigger port or software trigger?
My experiment setup is shown by the ascii art:
+--------------------+ +---------------------+ +---------+
| Signal Generator |---sync--| DAQ2 External Trigger|---TX--->| Scope |
+--------------------+ +---------------------+ +---------+
| ^
| |
(Also connected to Scope to measure sync reference)----+
I set the scope trigger on the TX signal and comparing the delay between the sync pulse from Signal Generator. The delay changes in different trigger.
My python code to generate the signal is shown as below:
import time
import adi
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
from scipy import signal
dev = adi.DAQ2("ip:analog.local")
def measure_phase_and_delay(chan0, chan1, window=None):
assert len(chan0) == len(chan1)
if window == None:
window = len(chan0)
phases = []
delays = []
indx = 0
sections = len(chan0) // window
for sec in range(sections):
chan0_tmp = chan0[indx : indx + window]
chan1_tmp = chan1[indx : indx + window]
indx = indx + window + 1
cor = np.correlate(chan0_tmp, chan1_tmp, "full")
# plt.plot(np.real(cor))
# plt.plot(np.imag(cor))
# plt.plot(np.abs(cor))
# plt.show()
i = np.argmax(np.abs(cor))
m = cor[i]
sample_delay = len(chan0_tmp) - i - 1
phases.append(np.angle(m) * 180 / np.pi)
delays.append(sample_delay)
return (np.mean(phases), np.mean(delays))
def gen_tone(fc, fs, NN):
N = NN / 8
fc = int(fc / (fs / N)) * (fs / N)
ts = 1 / float(fs)
t = np.arange(0, N * ts, ts)
i = np.cos(2 * np.pi * t * fc) * 2 ** 15
q = np.sin(2 * np.pi * t * fc) * 2 ** 15
Xn = i + 1j * q
# Xn = np.pad(Xn, int(NN - N))
Xn = np.pad(Xn, (0, int(NN - N)), "constant")
return Xn
# Configure properties
print("--Setting up chip")
dev._ctx.set_timeout(3000)
dev.rx_enabled_channels = [0]
dev.tx_enabled_channels = [0]
RUNS = 100
N = int(1024*8)
dev.rx_buffer_size = N
dev.tx_cyclic_buffer = False
fs = int(dev.sample_rate)
iq1 = gen_tone(fs / 20, fs, N)
print("TX SYNC START AVAILABLE:", dev.tx_sync_start_available)
print("RX SYNC START AVAILABLE:", dev.rx_sync_start_available)
# dev._rxadc.reg_write(0x4a3, 25)
so = []
po = []
# Collect data
for r in range(RUNS):
dev.rx_sync_start = "arm"
dev.tx_sync_start = "arm"
if not ("arm" == dev.tx_sync_start == dev.rx_sync_start):
raise Exception(
"Unexpected SYNC status: TX "
+ dev.tx_sync_start
+ " RX: "
+ dev.rx_sync_start
)
dev.tx_destroy_buffer()
dev.rx_destroy_buffer()
dev._rx_init_channels()
dev.tx(iq1)
#dev.tx_sync_start = "trigger_manual"
input("Press Enter to continue...")
if not ("disarm" == dev.tx_sync_start == dev.rx_sync_start):
raise Exception(
"Unexpected SYNC status: TX "
+ dev.tx_sync_start
+ " RX: "
+ dev.rx_sync_start
)
dev.rx_sync_start = "arm"
dev.tx_sync_start = "arm"
if not ("arm" == dev.tx_sync_start == dev.rx_sync_start):
raise Exception(
"Unexpected SYNC status: TX "
+ dev.tx_sync_start
+ " RX: "
+ dev.rx_sync_start
)
input("Press Enter to continue...")
