More progress today:
"Daniel aka CyReVolt 🐢: Transferring code to the CVITek 1800B worked with my tool. There was no output on the UART though. I'll see if the SRAM address is different, which isn't described in the manual. UART0 seems to have the same base address per the manual."
"plat/cv180x/include/platform_def.h
296: #define VC_RAM_BASE 0x3BC00000 // Shadow_vc_mem"
"Daniel aka CyReVolt 🐢: aha aha - 0x3BC00000 - neither "VC RAM" nor that address is mentioned in the manual"
"Daniel aka CyReVolt 🐢: THAT WORKS! VROOM VROOM! 🥳"
"I have now successfully run my own code on
- Duo (CV1800B)
- Duo 256M (SG2002)
- Duo S (SG2000)
The CV1800B has its SRAM at a different base address.
UART0 is mapped to the same address for all three."
His "own code" is written in Rust. Blergh for some people, ++ for others :-)
A note on chip names and companies ... Sophgo bought Cvitech a year or two ago, so CV1800B and SG200* share lineage. Also, a well informed Chinese person on Telegram said a couple of days ago that Sophgo and Radxa are parts of the same company, or fall under the same umbrella company (Bitmain?). I just found this repo, which lends support to this:
https://github.com/radxa/bm-bootloader-arm64