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+--- Thread: Faster OS test deployments - Faster UART? (/showthread.php?tid=20190)
Faster OS test deployments - Faster UART? - WhiteHexagon - 02-11-2026
I have an SD Card extender for booting my under-development OS. But I'm tired of switching it in/out for each build every few minutes. So I had the idea to just transmit my builds over the UART interface!
The UART seems to default to 115,200 (from u-boot?) and is working fine with my serial USB adapter. However this baud rate is going to be too slow for my 10MB debug builds.
So I wanted to try 1.5Mbps with the UART divisor of 0x1, but it doesnt seem to work (using linux util 'screen' but also tried my own Zig UART code).
My question is, how do I set the APB2 clock dividers and UART0 divider to match any of the standard baud rates please? and is there a limit on UART0? I seem to recall a limit elsewhere related to the modem, but I cant find the details now.
Also, from what I brute forced so far, it seems like I can only approximate other baud settings? In fact the default UART divider of 0xd seems to also be an approximation? Is that the best I can do here?
Alternative would be to get the USB port working, but I think that might be quite a bit more challenging...