Date: Fri, 25 Nov 2016 06:07:25 -0800 From: Mark Millard <markmi@dsl-only.net> To: Michael Sperber <sperber@deinprogramm.de> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Can't get 11.0-RELEASE to boot on Banana PI M3 Message-ID: <9211EF99-1E69-4BC0-91CC-DF6604FE8655@dsl-only.net> In-Reply-To: <20161125105751.8F15A406061@ip-64-139-1-69.sjc.megapath.net> References: <20161125105751.8F15A406061@ip-64-139-1-69.sjc.megapath.net>
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On 2016-Nov-25, at 2:57 AM, Hal Murray <hmurray at megapathdsl.net> wrote: > 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 I use one of those from adafruit for a BPi-M3, a RPI2B V1.1, or a Pine64. > 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. === Mark Millard markmi at dsl-only.nethelp
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