Yes, you're right, that's clearly nonsense.
Why would the E3 generate an inverted signal, anyway? If it's just the raw output from the processor (which I think it is) then it should be standard TTL levels, because it's supposed to be fed into something like a MAX232 for conversion to RS232 levels. Inverting it but leaving it at TTL seems very odd.
On Thu, 4 Apr 2019, 14:25 Sean Furey, sean-lists-e3-hacking@furey.me.uk wrote:
On Thu, Apr 04, 2019 at 12:18:56PM +0200, David Given wrote:
Provided the E3 and the USB device ran off isolated supplies, you might
be
able to get away with connecting the 5V (or whatever) on the USB adapter
to
the GND on the jack. That would cause the logic levels to be interpreted inverted.
I'd have thought that would make the USB dev see the E3's 0V - 5V as 5V - 10V, and the E3 to see the USB's 0V - 5V as -5V - 0V. Which doesn't sound like it helps - am I missing something?
Sean
e3-hacking mailing list e3-hacking@earth.li https://www.earth.li/mailman/listinfo/e3-hacking