TinyUF2 in pico-ice-sdk

[josuah]

Hello, and thank you for this open-source implementation of TinyUF2!

We are using it as part of an SDK, to provide UF2 flashing for an iCE40 FPGA board.
An RP2040 MCU is handling USB and connected to the FPGA (to start and stop it, i/o with it...) and its flash (for programming it).
The TinyUF2 bootloader have been reduced to a "smol" library that is now part of the pico-ice-sdk.

https://github.com/tinyvision-ai-inc/pico-ice-sdk/tree/main/src/tinyuf2

[josuah]

To be sure, is the license compatible with integration in the pico-ice-sdk?

[hathach]

since pico-ice-sdk is MIT license, and TinyUF2 is also MIT. I think we are all good.

[josuah]

Thank you for the confirmation! I will make sure to clean-up the LICENSE file to specify the origin of the various components involved after the project is completed.

[josuah]

The way it turned out, the TinyUF2 library we came-up with from your implementation could eventually be integrated directly into TinyUSB, just like it was done for DFU.

The TinyUF2 code you implemented is really portable, helping a lot with this.

Does it make sense?

[josuah]

I confirm, this works very well!
https://github.com/tinyvision-ai-inc/pico-ice-sdk/blob/develop/CMakeLists.txt#L56-L59

I needed to copy then modify main.c to allow to cohabitate with the rest of the firmware, and declare an MSC interface in the existing usb_descriptors.c (the normal TinyUSB way).

This appears to work well! :)

It is used to program an FPGA and these UF2 toolbox was developed for this occasion: https://github.com/tinyvision-ai-inc/uf2-utils

Thank you for the advises!

[hathach]

glad that works for you. How differences is your main.c ? If not too much, we can actually make pico-ice as part of tinyuf2, maybe under port/rp2040_ice. This may come handy if there is more boards with pico + ice combo in the future ?

[josuah]

Apologies for the long silence, I was on the leave.

Reviewing again, the only change needed was to remove main() (because there is another main for the user application running at the same time) and adding a board definition file.

If everything but main() is moved to a separate file, then it would be possible to use TinyUF2 as a library.

There are other dependencies from the pico-ice-sdk:

• ice_spi.c - bit-banged SPI because of wrong pinout of early version, but now it is good to convert it to hardware SPI,
• ice_flash.c - flash I/O commands to program it.
• pico_ice.h - RP2040 board definition that will be upstreamed in the future.

Two ways to do it I can think of:

• using the pico-ice-sdk to provide a maintained version of these small functions
• we provide an implementation of these functions directly into the board definition.

if there is more boards with pico + ice combo in the future

There are a few hobby projects already around, but do not seems largely produced for now... Maybe more soon!

[hathach]

no problems, we are all busy. I think either having low level flash as local files of tinyuf2 or including pico-ice-sdk as submodule are OK. We don't have to get it right at the first time, we only need to make it convenience for us (maintainer) and other maker with same flashing (probably with different led, flash device etc ..) currently ice-pico is the only variant so there should be no problems. We could update/upgrade it later when needed. Feel free to submit PR whenever you have time to do so, I am sure will help to review it.

[josuah]

Many thanks for your openness.
I will do my best!