(08-08-2020, 04:44 PM)Skirmisher Wrote: I'm looking around for appropriate level-shifting adapters, trying to find one that supports the RP64's default baud rate of 1.5M. Does anyone have such a device to recommend?
I suggest looking up the data sheet for the chip on any adapter you consider buying. The data sheet will say what speeds are supported. (You can usually find it quickly by searching the pdf for "bps" or "baud".) If the product listing doesn't state what chip is used, avoid it.
Do not trust the speed claims in cheap adapter product listings. I bought one that claimed to support 1.5mbps, but that claim was a lie. It has a CP2102 chip, and produces garbage at the RockPro64's default speed. Many other adapters use the same chip. I later looked up the chip's data sheet, which confirms that speed is not supported.
You can configure u-boot to pass a slower bit rate to the kernel and successfully launch linux that way, but some of the early boot process messages will still be sent at the default speed, so troubleshooting anything that early will be troublesome with an adapter that can't handle it.
