Date: Fri, 25 Nov 2016 02:57:51 -0800 From: Hal Murray <hmurray@megapathdsl.net> To: Michael Sperber <sperber@deinprogramm.de> Cc: freebsd-arm@freebsd.org, hmurray@megapathdsl.net Subject: Re: Can't get 11.0-RELEASE to boot on Banana PI M3 Message-ID: <20161125105751.8F15A406061@ip-64-139-1-69.sjc.megapath.net> In-Reply-To: Message from Michael Sperber <sperber@deinprogramm.de> of "Fri, 25 Nov 2016 11:03:27 %2B0100." <y9loa13ub9s.fsf@jellaby.local>
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sperber@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. -- These are my opinions. I hate spam.
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