phyduino/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.

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.
 
import time  # sleep() for pauses
 
import phyduino as mcu  # the Phyduino Pico library, used as mcu.<name>
 
MAX_VOLTS = 9  # 5, 9, 12, 15 or 20
 
serial = mcu.uart(0)  # UART0: TX on D1, 115200 bits per second
 
 
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
 
 
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()))
 
while True:  # repeats until stopped: Interrupt in PyCharm, or mpremote soft-reset
    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)
    time.sleep(1)  # once a second