loopback read CH1

fast-servo/pyfastservo/adc.py

@@ -152,6 +152,8 @@ def configure_ltc2195():
         main_adc_test_mode(spi, False)
         verify_adc_registers(spi, {0x02: 0x11})  # Verify test mode is off
         
+        print_adc_channels()
+
         enable_adc_afe()
 
     finally:

fast-servo/pyfastservo/dac.py

@@ -127,13 +127,13 @@ def configure_ad9117():
         configure_dac(spi)
         dac_self_calibration(spi)
 
+        # Enable DAC outputs
+        spi_write(spi, 0x01, spi_read(spi, 0x01) & ~((1 << 4) | (1 << 3)))
+
         power_down(0, False)
         power_down(1, False)
         manual_override(True)
 
-        # Enable DAC outputs
-        spi_write(spi, 0x01, spi_read(spi, 0x01) & ~((1 << 4) | (1 << 3)))
-
         print("AD9117 configuration completed successfully")
         return True
 

fast-servo/pyfastservo/loopback.py

@@ -0,0 +1,48 @@
+import time
+from pyfastservo import adc, dac
+from pyfastservo.common import (
+    ADC_CH1_HIGH_ADDR,
+    ADC_CH1_LOW_ADDR,
+    CH1_HIGH_WORD_ADDR,
+    CH1_LOW_WORD_ADDR,
+    read_from_memory,
+    write_to_memory
+)
+
+def read_adc():
+    adc_value = adc.read_adc_channel(ADC_CH1_HIGH_ADDR, ADC_CH1_LOW_ADDR)
+    return adc_value
+
+def write_dac(value):
+    dac.set_dac_output(value)
+
+def read_dac():
+    high_word = read_from_memory(CH1_HIGH_WORD_ADDR, 1)[0]
+    low_word = read_from_memory(CH1_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()

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"; });