Drive Strength

Drive strength controls the output current. The default is 4mA, but you can set 2mA, 4mA, 8mA, or 12mA with the drive subcommand.

To measure output current, connect an ammeter (be careful!) and run:

L:/>gpio 1 func:sio dir:out pull:none drive:2mA put:1
L:/>gpio 1 func:sio dir:out pull:none drive:4mA put:1
L:/>gpio 1 func:sio dir:out pull:none drive:8mA put:1
L:/>gpio 1 func:sio dir:out pull:none drive:12mA put:1

To measure sink current:

L:/>gpio 1 func:sio dir:out pull:none drive:2mA put:0
L:/>gpio 1 func:sio dir:out pull:none drive:4mA put:0
L:/>gpio 1 func:sio dir:out pull:none drive:8mA put:0
L:/>gpio 1 func:sio dir:out pull:none drive:12mA put:0

Results for Pico and Pico 2:

Output current:

drive setting	Pico	Pico 2
2mA	20.2mA	20.3mA
4mA	30.0mA	30.0mA
8mA	48.0mA	48.7mA
12mA	56.5mA	57.1mA

Sink current:

drive setting	Pico	Pico 2
2mA	25.6mA	27.6mA
4mA	37.5mA	40.6mA
8mA	61.2mA	67.1mA
12mA	72.2mA	79.0mA

The set drive strength is only a rough guide; actual current depends on load and circuit characteristics. Higher settings allow more current, which may help with high-load devices.