From 79315d3d1bfd58a5ffdb789f8641ead0f1eb80c9 Mon Sep 17 00:00:00 2001
From: Florian Agbuya <fa@m-labs.ph>
Date: Tue, 20 Aug 2024 10:03:30 +0800
Subject: [PATCH] test nixbld

---
 fast-servo/pyfastservo/loopback.py | 49 ++++++++++++++++++++++++++++++
 flake.nix                          |  2 +-
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 fast-servo/pyfastservo/loopback.py

diff --git a/fast-servo/pyfastservo/loopback.py b/fast-servo/pyfastservo/loopback.py
new file mode 100644
index 0000000..12f0a8e
--- /dev/null
+++ b/fast-servo/pyfastservo/loopback.py
@@ -0,0 +1,49 @@
+import time
+from pyfastservo import adc, dac
+from pyfastservo.common import (
+    ADC_CH0_HIGH_ADDR,
+    ADC_CH0_LOW_ADDR,
+    CH0_HIGH_WORD_ADDR,
+    CH0_LOW_WORD_ADDR,
+    read_from_memory,
+    write_to_memory
+)
+###
+
+def read_adc():
+    adc_value = adc.read_adc_channel(ADC_CH0_HIGH_ADDR, ADC_CH0_LOW_ADDR)
+    return adc_value
+
+def write_dac(value):
+    dac.set_dac_output(value)
+
+def read_dac():
+    high_word = read_from_memory(CH0_HIGH_WORD_ADDR, 1)[0]
+    low_word = read_from_memory(CH0_LOW_WORD_ADDR, 1)[0]
+    return (high_word << 8) | low_word
+
+def perform_loopback_test(test_value):
+    print(f"Setting DAC output to {test_value}...")
+    write_dac(test_value)
+    time.sleep(0.1)  # Allow time for the signal to stabilize
+
+    print("Reading ADC value...")
+    adc_value = read_adc()
+    print(f"ADC readback: {adc_value}")
+
+    print("Reading DAC value...")
+    dac_value = read_dac()
+    print(f"DAC readback: {dac_value}")
+
+    if abs(test_value - adc_value) <= 2 and abs(test_value - dac_value) <= 2:
+        print("Loopback test PASSED!")
+    else:
+        print("Loopback test FAILED!")
+        print(f"Expected: {test_value}, ADC: {adc_value}, DAC: {dac_value}")
+
+def main():
+    test_value = 0x2000  # Mid-range value (8192 in decimal)
+    perform_loopback_test(test_value)
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/flake.nix b/flake.nix
index 962210d..80f79f3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -481,7 +481,7 @@
         inherit migen misoc vivado;
       };
       packages.armv7l-linux = {
-        inherit fast-servo-gateware linien-server;
+        inherit fast-servo-gateware linien-server pyfastservo;
       } //
       (board-package-set { board = "zc706"; }) //
       (board-package-set { board = "fast-servo"; });