Unaccurate measurments vs nrf connect

[klaudiawro]

Hello i am using the API for an automated production script, one of the steps is measuring power consumption, the API works as intended maybe 50% of the time, the other times it returns values that are very low (0.03 - 0.08 mA) compared to what it should be (around 2.7mA) when the same pcb is measured with nrf connect the correct value is disaplayed, this is the code that is used:

def connect_ppk2_mp():
stem.usb.setPortEnable(USBHubPort.PPK2)
ppk2s_connected = PPK2_API.list_devices()
global ppk2_test

if len(ppk2s_connected) == 1:
    ppk2_port = ppk2s_connected[0][0]
    ppk2_serial = ppk2s_connected[0][1]
else:
    print(f"error: none.or.too.many.connected.PPK2: {ppk2s_connected}")
    sys.exit(1)

ppk2_test = PPK2_API(ppk2_port, exclusive=True)

ppk2_test.ser.reset_input_buffer()
ppk2_test.ser.reset_output_buffer()
sleep(0.1)

ppk2_test.get_modifiers()
ppk2_test.use_source_meter()
ppk2_test.set_source_voltage(3000)
ppk2_test.toggle_DUT_power('ON')

sleep(0.1)
ppk2_ready_event.set()

def measure_current_ppk2_mp(seconds):
all_samples = []
start_time = time.time()

# Clear buffer to ensure fresh data
ppk2_test.get_data()
sleep(0.1)

# Start measuring and allow stabilization
ppk2_test.start_measuring()
time.sleep(0.2)

end_time = start_time + float(seconds)

while time.time() < end_time:
    read_data = ppk2_test.get_data()
    if read_data:
        samples, _ = ppk2_test.get_samples(read_data)
        all_samples.extend(samples)  # Keep all data (no [::100] filtering)

ppk2_test.stop_measuring()

if all_samples:
    average = sum(all_samples) / len(all_samples)
    print(len(all_samples))
    print(f"{average:.6f} mA")
    return f"{average:.6f}"

print("error: current measuring failed")
return "0.000000"

For the record, i am using the PPK2_MP version

[furhadjidda]

you might want to toggle_DUT_power("ON") before starting the measurement. I had missed this in my script before i could get it to work.