Can't get 11.0-RELEASE to boot on Banana PI M3
Hal Murray
hmurray at megapathdsl.net
Fri Nov 25 10:58:01 UTC 2016
sperber at deinprogramm.de said:
> Ah, thanks ... but that's not standard RS232, right? (BPI homepages says
> "TTL".) If it isn't, what kind of hardware connects to that?
The normal setup for RS232 is that the transmit and receive signals come out
of a big chip (SOC, or PCI UART, or USB UART, or ...) and then go through a
level converter which is typically a MAX-232 or one of many clones or
variants. The "TTL" is telling you that it doesn't have that level converter
chip.
You can either add a level converter chip and then plug it into a real RS-232
port, or find some setup that also doesn't have the level converter and
speaks TTL levels. Adafruit and probably many others sell a USB UART without
the level converter for applications like this.
https://www.adafruit.com/product/954
Sometimes, TTL means 3V CMOS levels and 5V from real TTL/CMOS will fry your
expensive chip. Best to check carefully. The above part says 3V. It also
has an extra power wire that you get to ignore.
--
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