arduino/phyduino_pico/usb_pd_power/main.py

Asks a USB-PD charger for up to MAX_VOLTS, then prints the board's profiles, the contract and the measured VBUS once a second.

Arduino has no match for this, so this uses mcu.usb_pd() and mcu.uart() from phyduino.py.

A charger takes the only USB-C port, so there is no USB connection to the computer while it is plugged in. Copy this main.py to the board so it runs by itself, and watch the output on UART0 (TX on D1, 115200 baud) with a USB-serial adapter. The green POK2 LED lights for the second profile (9 V), POK3 for the third (the 12, 15 or 20 V of MAX_VOLTS).

Warning

VBUS also feeds the VIN pin, so VIN follows the contract: disconnect anything on VIN that can't take the voltage you ask for.

The request lasts until the board loses power.

Output

Profiles: 5 V 2 A, 9 V 1 A
Contract: offer 2, 1.00 A    VBUS 9.01 V

# USB-PD power: asks a USB-PD charger for up to MAX_VOLTS, then prints the
# board's profiles, the contract and the measured VBUS once a second.
#
# A charger takes the only USB-C port, so there is no USB connection to the
# computer while it is plugged in. Copy this main.py to the board so it runs
# by itself, and watch the output on UART0 (TX on D1, 115200 baud)
# with a USB-serial adapter. The green POK2 LED lights for the second
# profile (9 V), POK3 for the third (the 12, 15 or 20 V of MAX_VOLTS).
#
# VBUS also feeds the VIN pin, so VIN follows the contract: disconnect
# anything on VIN that can't take the voltage you ask for.
# The request lasts until the board loses power.
 
from arduino import *  # the Arduino-style functions: pinMode(), digitalWrite(), delay(), ...
import phyduino as mcu  # the Phyduino Pico library, for mcu.usb_pd() and mcu.uart()
 
MAX_VOLTS = 9  # 5, 9, 12, 15 or 20
 
serial = None  # the serial port for the output; setup() fills this in
usb = None  # the USB-PD controller; setup() fills this in
 
 
def report(text):
    """Prints text, and sends it out of UART0 too, as USB is taken by the charger."""
    print(text)
    serial.write(text + "\r\n")  # "\r\n" ends the line for a serial terminal
 
 
def setup():
    global serial, usb  # setup() fills in both
    serial = mcu.uart(0)  # UART0: TX on D1, 115200 bits per second
    usb = mcu.usb_pd()  # the on-board STUSB4500 USB-PD controller
    usb.request(MAX_VOLTS)  # ask the charger for up to MAX_VOLTS
    # profiles() lists the (volts, amps) the board offers; "%g" drops trailing zeros.
    report("Profiles: " + ", ".join("%g V %g A" % p for p in usb.profiles()))
 
 
def loop():
    volts, amps = usb.contract()  # what the charger agreed to supply
    position = usb.contract_position()  # which charger offer is in use; 0 if none
    if position:  # 0 counts as false
        report("Contract: offer %d, %.2f A    VBUS %.2f V" % (position, amps, volts))
    else:
        report("No PD contract (plain USB)    VBUS %.2f V" % volts)
    delay(1000)  # once a second
 
 
# Do not edit below this line: it runs setup() once, then loop() over and over.
def main():
    setup()  # runs once, at the start
    while True:  # repeats until stopped: Interrupt in PyCharm, or mpremote soft-reset
        loop()
 
 
# True when this file is run, but not when another file imports it.
if __name__ == "__main__":
    main()