printing to terminal with `elf2uf2` (without a probe) on the pico/pico w

[anandijain]

hello and apologies if this isn't the best place to ask this.

i am trying to run a basic hello world program that prints to the terminal on my pico w.

im able to get examples/rp/src/bin/wifi-blinky.rs example to work by following the instruction in the embassy book (replacing probe-rs with elf2uf2-rs in .cargo/config.toml: https://embassy.dev/book/#_how_to_deploy_to_rp2040_without_a_debugging_probe

my issue is I just can't seem to get any terminal output using info! commands. is it possible to log information to my terminal without a debug probe? i am new to embedded programming

my code is here. when i do a cargo run --release --bin hello_world, I can see that the pico is getting flashed (because of the page and address info):

PS C:\Users\anand\src\embedded\pico_w_rust_test> c r --release --bin hello_world
   Compiling pico_w_rust_test v0.1.0 (C:\Users\anand\src\embedded\pico_w_rust_test)
...
     Running `elf2uf2-rs --deploy --serial --verbose target\thumbv6m-none-eabi\release\hello_world`
Found pico uf2 disk E:\
Detected FLASH binary
Mapped segment 0x10000100->0x100001c0 (0x10000100->0x100001c0)
Mapped segment 0x100001c0->0x10003804 (0x100001c0->0x10003804)
Mapped segment 0x10003804->0x10003e30 (0x10003804->0x10003e30)
Mapped segment 0x10003e30->0x1000402c (0x20000000->0x200001fc)
Mapped segment 0x10000000->0x10000100 (0x10000000->0x10000100)
Transfering program to pico
Page 0 / 65 0x10000000
Page 1 / 65 0x10000100
Page 2 / 65 0x10000200
...
Page 64 / 65 0x10004000

PS C:\Users\anand\src\embedded\pico_w_rust_test> 

So it seems like everything runs (just like with the wifi_blinky example). but no output in my terminal

any help would be greatly appreciated! thank you!

[JonathanPlasse]

Hello, Without debug probe, you cannot use defmt logging. If you have another pico, you could make it into a probe and use it on the other. Or as an alternative, you can use the usb_serial.rs example to read and write message to the Pico. You can then use pyserial read and write to the usb serial or any other similar program. This is the code I use on Linux.

import serial

def main():
    with serial.Serial(
        port="/dev/serial/by-id/usb-Embassy_USB-serial_example_12345678-if00",
        baudrate=921600,
        timeout=1,
    ) as ser:
        while ser.is_open:
            message = input()
            if len(message) == 0:
                message = " "
            ser.write(message.encode())
            while ser.in_waiting == 0:
                pass
            response = ser.read(ser.in_waiting)
            print(response.decode())

if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass