RP235x support

[brandonros]

Do we know enough yet what we need to do to be able to support RP2350 instead of just RP2040?

[CBJamo]

Initial support is coming in #3243, though much work remains.

[BjornTheProgrammer]

I've preordered the Raspberry Pi Pico 2 and would be willing to test it on actual hardware and write/verify some examples.

[ionspin]

I've got a couple of Tiny2350 from pimoroni, got blinky to work without much trouble except that elf2uf2 would work because of hard float in the executable.

elf2uf2-rs ./target/thumbv8m.main-none-eabihf/debug/blinky                                                                                                                                                                            
Error: "HARD-FLOAT not supported"

Worked around that by using picotool and this small script:
picotool-run.sh

picotool uf2 convert -t elf $1 out.uf2
picotool load out.uf2
picotool reboot

in .cargo/config.toml for the runner

This is a quick workaround until we get support in elf2uf2 for thumbv8m.main-none-eabihf or full probe-rs support.

[CBJamo]

JP has a pull request for elf2uf2-rs to allow use with the rp2350. JoNil/elf2uf2-rs#33

[thejpster]

However, I recommend switching to picotool because it's faster and doesn't require mounting the disk drive. Binary releases are available from https://github.com/raspberrypi/pico-sdk-tools/releases

[ionspin]

I'm running into a bit of issue, I'm getting different behavior after picotool reboot and resetting the RP2350 (using reset button on Tiny2350, or just unplugging the Pico2). After picotool reboot it works fine every time, but the reset gets it into a partially broken state.

This is more or less the current setup, it's reproducible if I remove the USB part and just leave the blinky loop

#[embassy_executor::main]
async fn main(spawner: Spawner) {
    let peripherals = embassy_rp::init(Default::default());


    let other_side_channel = OTHER_SIDE_CHANNEL.init(Channel::new());

    UsbHandler::new(peripherals.USB, other_side_channel, spawner, true);


    
    let delay = 100;

    let mut counter = 0;
    #[cfg(feature = "tiny2350")]
    {
        let mut red_led = Output::new(peripherals.PIN_18, Level::Low);
        let mut green_led = Output::new(peripherals.PIN_19, Level::Low);
        let mut blue_led = Output::new(peripherals.PIN_20, Level::Low);
        green_led.set_high();
        blue_led.set_high();
        red_led.set_high();
        loop {
            log::info!("Tick {}", counter);
            counter += 1;
            red_led.set_low();
            Timer::after_millis(delay).await;

            red_led.set_high();
            Timer::after_millis(delay).await;

            green_led.set_low();
            Timer::after_millis(delay).await;

            green_led.set_high();
            Timer::after_millis(delay).await;

            blue_led.set_low();
            Timer::after_millis(delay).await;

            blue_led.set_high();
            Timer::after_millis(delay).await;
        }
    }

    #[cfg(feature = "pico2")]
    {
        let mut led =  Output::new(peripherals.PIN_25, Level::Low);
        led.set_low();
        loop {
            log::info!("Tick {}", counter);
            counter += 1;
            led.set_high();
            Timer::after_millis(delay).await;
            led.set_low();
            Timer::after_millis(delay).await;
        }
    }

}

On picotool reboot the blinks and log-over-usb works fine, as expected, but when using reset on Tiny2350 or unplugging and plugging in on Pico2, the blinks are not there, while log-over-usb gets set up most of the time.

Any clues on why this is happening? I'm planning to solder the headers tomorrow so I can try to set up UART and see if I get more info that way.

[ionspin]

I don't think this is correct:

embassy/embassy-rp/src/clocks.rs

Line 515 in 423e5d7

// Configure tick generation on the 2040. On the 2350 the timers are driven from the sysclk.

I suspect picotool reboot initializes ticks, and embassy-rp does not, here's my log collected through defmt-uart

0.037927 INFO  Defmt serial test
0.038167 INFO  USB: config_descriptor used: 94
0.038175 INFO  USB: bos_descriptor used: 12
0.038182 INFO  USB: msos_descriptor used: 0
0.038188 INFO  USB: control_buf size: 256
0.038432 INFO  Defmt tick 0
0.238699 INFO  Defmt tick 1
0.364565 DEBUG SET_CONFIGURATION: configured
0.365786 DEBUG Set line coding to: LineCoding { stop_bits: One, data_bits: 8, parity_type: None, data_rate: 9600 }
0.438751 INFO  Defmt tick 2
0.537203 DEBUG Set dtr true, rts true
0.638785 INFO  Defmt tick 3
0.838805 INFO  Defmt tick 4
1.038821 INFO  Defmt tick 5
1.238837 INFO  Defmt tick 6
1.438854 INFO  Defmt tick 7
1.638870 INFO  Defmt tick 8
1.838886 INFO  Defmt tick 9
2.038903 INFO  Defmt tick 10
2.238919 INFO  Defmt tick 11




0.000000 INFO  Defmt serial test
0.000000 INFO  USB: config_descriptor used: 94
0.000000 INFO  USB: bos_descriptor used: 12
0.000000 INFO  USB: msos_descriptor used: 0
0.000000 INFO  USB: control_buf size: 256
0.000000 INFO  Defmt tick 0
0.000000 DEBUG SET_CONFIGURATION: configured
0.000000 DEBUG Set line coding to: LineCoding { stop_bits: One, data_bits: 8, parity_type: None, data_rate: 9600 }
0.000000 DEBUG Set dtr true, rts true

First part is picotool reboot and second is manual restart, note the timestamps

I'll try to submit a pull request for this today if I'm right and setting ticks up fixes it.

[CBJamo]

Nice catch. When doing the initial support I loaded all my firmware using the uf2 method, and so the usb bootloader must've set up timer0 for me. Since the bootrom source is available it'd probably be a good idea to take a look through for anything else it was doing for me.

[brandonros]

just calling this out for anybody in case they weren’t aware

https://hackaday.com/2024/09/04/the-worsening-raspberry-pi-rp2350-e9-erratum-situation/

[ionspin]

I'm working on adding TRNG support, hopefully I'll have a draft this weekend.

[sndnvaps]

It otc 14. Is any progress for the RP2350 Pico2...

[CBJamo]

Embassy doesn't have board specific code, but embassy does support the rp2350, yes. Check out the examples here: https://github.com/embassy-rs/embassy/tree/main/examples/rp23