plotter/main.py

Prints the shield's readings four times a second as label:value pairs, for a serial plotter: the temperature from the raw sensor (A1) and through the amplifier, the encoder position, the selected channel (0 or 3), the pot and VBUS voltages. The Phyduino's LED blinks while it runs.

Pressing the knob switches between A0 and A3. It only tells the code where JP2 is, so move JP2 to match (A3 is JP2 on EXT). Green LED: A0, red LED: A3, both on: the A3 ADC did not respond (until the next press). The two temperatures should agree to within about 3 °C; the raw sensor line is coarser and noisier.

Connect

JP3 (VIO) on 3.3 V, JP4 on 5 V, JP1 on INT and JP2 on INT (A0) to start.

Uses

encoder(): Encoder.position(), Encoder.on_press(); set_output_pin(), temperature(), temperature_from_volts(), raw_sensor_volts(), pot_volts(), green_led, red_led; mcu.Led, mcu.vbus_volts()

# Prints the shield's readings four times a second as label:value pairs, for a
# serial plotter: the temperature from the raw sensor (A1) and through the
# amplifier, the encoder position, the selected channel (0 or 3), the pot and
# VBUS voltages. The Phyduino's LED blinks while it runs.
#
# Needs analog_shield.py on the board, JP3 (VIO) on 3.3 V, JP4 on 5 V and JP1
# on INT (the on-board sensor). Starts reading the amplifier on A0 (JP2 on INT).
# Pressing the knob switches between A0 and A3: it only tells the code where
# JP2 is, so move JP2 to match (A3 is JP2 on EXT). Green LED: A0, red LED: A3,
# both on: the A3 ADC did not respond (until the next press).
#
# The two temperatures should agree to within about 3 C. The raw sensor line is
# coarser and noisier, as the RP2040's ADC reads A1 with no amplifier.
 
import analog_shield as shield
import phyduino as mcu
import time
 
_channel = "A0"
 
def channel_select():
    """Event handler for Encoder switch press."""
    global _channel
    _channel = "A3" if _channel == "A0" else "A0"
    shield.set_output_pin(_channel)
    shield.green_led.value(_channel == "A0")
    shield.red_led.value(_channel == "A3")
 
 
# Set up board before entering loop
Knob = shield.encoder()
 
shield.green_led.on()
shield.red_led.off()
shield.set_output_pin(_channel)
 
Knob.on_press(channel_select)     # Set up event handler for button press
BuiltinLed = mcu.Led()
BuiltinLed.on()
 
while True:
    BuiltinLed.toggle()
 
    try:
        AmpTemperature = shield.temperature()
    except OSError:                 # External ADC did not respond.
        shield.green_led.on()       # indicate error has occurred.
        shield.red_led.on()
        time.sleep(0.25)
        continue
 
    EncoderCount = Knob.position()
    PotVoltage = shield.pot_volts()
    RawTemp = shield.temperature_from_volts(shield.raw_sensor_volts())
    VBusVoltage = mcu.vbus_volts()
    SelectedChannel = 0 if _channel == "A0" else 3
 
    print("RawTemp:%.1f,Temp:%.1f,EncPosition:%d,Channel:%d,Pot:%.3f,Vbus:%.2f"
          % (RawTemp, AmpTemperature, EncoderCount, SelectedChannel, PotVoltage, VBusVoltage))
 
    time.sleep(0.25)