11–20 of 22 posts
In principle, you could boot the RP2040 over SWD. It'd be much more difficult to code, but the possibility is there...
https://github.com/pimoroni/picovision/blob/main/drivers/dv_...
This is awesome. I've had similar ideas but wasn't able to do any prototyping yet as I only have Pico 2 boards that don't expose the CSn pin in the pinout. Rather than UART booting every time I thought it might be nice to use UART Boot just as a way to deliver the firmware update to the sub chip - so the UART image you load would just be a program that accepts a larger image (over UART again) and would write to the f…
In principle, you could boot the RP2040 over SWD. It'd be much more difficult to code, but the possibility is there...
We (Pimoroni) actually shipped this technique in PicoVision, used to load the “GPU” firmware (an RP2040 used to offload the HDMI signal generation) at runtime- https://github.com/pimoroni/picovision/blob/main/drivers/dv_...
This is great for making audio modules, where the firmware is be small and operates on a big audio buffer. Since the biggest available PSRAM chips are 8MB, this combined 16 MB could hold around 3 minutes of mono 16-bit audio, which allows for a very nice multi track looper.
Another way (in case there's no other MCU to help with uart bootstrap) would be to add a logic chip to multiplex the CS line between Flash and the first PSRAM - copy firmware to flash and then switch to using ram.
Earlier quoted context omitted.
We (Pimoroni) actually shipped this technique in PicoVision, used to load the “GPU” firmware (an RP2040 used to offload the HDMI signal generation) at runtime- https://github.com/pimoroni/picovision/blob/main/drivers/dv_...
What are the advantages of doing this instead booting it through UART? Speed perhaps?
this is also how some BLE controller boot.
Later, Espressif took that chip, modified bootrom to be able to boot from an SPI flash as well, and marketed that variant as "ESP8266". Serial bootloader was kept as a debug/programming interface, and that was inherited to ESP32 and later chips. All of which can boot directly from serial.
Are there any off-the-shelf hobbyist boards that expose QSPI CSn (pin 75 on the RP2350B?) and QPI_SD1-3 signals to a header or pin? Doesn't seem like the official Pico 2 or the Adafruit or Pimoroni versions of the Pico 2 expose access to these signals without modifying the board, which most people won't be able to do.
In principle, you could boot the RP2040 over SWD. It'd be much more difficult to code, but the possibility is there...
Are you implying the SWD signals would send the RAM contents every time? If I had to do that, I would first use a logic analyzer like Saleae to capture the SWD signals of a JLink performing the necessary operations to load the image into RAM. Then figure out, from the bytes that get send and received, whatever needs to be parameterized, and where to put the image data itself, perhaps by capturing different scenarios,…