Welcome to ch554_sdcc Discussions!

[nerdralph]

👋 Welcome!

Feel free to use discussions for things that aren't really issues or explicit feature requests.

[prosper00]

Awesome project! This is an exciting little chip. I've been wanting to learn 8051 development as well as USB for a while now, and this seems like a great little platform to tinker with. I've got a few sleeves of chips in the mail, and am starting to get things set up.

Perhaps a bit ambitious for me, but, ultimately I'd love to write a firmware to use these chips as SPI to USB bridges, and a companion library for Arduino. My end goal would be to use these to provide USB-host and USB-device functions to other microcontrollers via SPI. This way, I could do most of the development and debugging of my firmwares on some other chip with a better development and debugging environment (and a greater flash cycle capacity), and implement the USB functions on the CH55x.

[nerdralph]

That's an interesting and ambitious idea. When you say Arduino, if you are referring to AVR, I don't think the debugging environment is any better. If you are talking about ARM Cortex-M devices, then sure, they have much better debugging infrastructure (SW-DP).

There's a couple things I like better with SDCC than avr-gcc. The first is inline asm is way easier with SDCC. It took me years to figure out gcc's inline asm constraints well enough to write functional inline asm... and I still wouldn't consider myself an expert.
https://www.avrfreaks.net/forum/avr-gcc-inline-assembler-concrete-documentation

The other thing is rather basic, but quite handy. SDCC allows extern __sbit definitions. So for example in a bit-bang I2C library you could declare:

extern __sbit I2C_SDA;
extern __sbit I2C_SCL;

Then in main.c, you could include the library header, and define I2C_SDA and I2C_SCL to use your chosen port/pin.

[prosper00]

Actually, I wouldn't write it specifically for Arduino. I'd probably do it up in plain C, and make it as platform-independent as I could - so that I could use it in as many different environments and platforms as possible. At present, i like the stm8 and stm32. Both have debug