phyduino/analog_shield/amplifier_chain/main.py

Prints the amplifier's gain and offset, then once a second the sensor's voltage read directly on A1, the same worked out from the amplifier's output, the amplifier's output (also on J8 pin 4) and the divided signal on A3.

Connect

JP4 on 5 V, JP1 on INT and JP2 on EXT. A meter on J8 pin 4 should match the opamp column.

Uses

raw_sensor_volts(), sensor_volts(), amplifier_volts(), output_volts(), amplifier_gain(), amplifier_offset_volts(); mcu.analog_averaging()

# Prints the voltage at each stage of the temperature amplifier, once a
# second, as columns:
#   A1       the sensor's voltage, read directly
#   sensor   the sensor's voltage, worked out back from the amplifier's output
#   opamp    the amplifier's output (J8 pin 4), sensor * gain - offset
#   A3       the amplifier's output after the R14/R15 divider
#
# Needs analog_shield.py on the board, JP4 on 5 V, JP1 on INT and JP2 on EXT.
# Check the opamp column with a meter on J8 pin 4. With JP1 on EXT, the
# sensor on J1 is measured instead.
 
import time  # sleep() for pauses
 
import analog_shield as shield  # the Analog Shield library, used as shield.<name>
import phyduino as mcu  # the Phyduino Pico library, used as mcu.<name>
 
mcu.analog_averaging(16)  # average 16 samples per reading: steadier
 
print("gain %.3f, offset %.3f V" % (shield.amplifier_gain(), shield.amplifier_offset_volts()))
print("A1      sensor  opamp   A3")
 
while True:  # repeats until stopped: Interrupt in PyCharm, or mpremote soft-reset
    print("%.3f   %.3f   %.3f   %.3f" % (
        shield.raw_sensor_volts(),
        shield.sensor_volts(),
        shield.amplifier_volts(),
        shield.output_volts(),
    ))
    time.sleep(1)