this post was submitted on 21 Jun 2023
2 points (100.0% liked)

Ask Electronics

3481 readers
1 users here now

For questions about component-level electronic circuits, tools and equipment.

Rules

1: Be nice.

2: Be on-topic (eg: Electronic, not electrical).

3: No commercial stuff, buying, selling or valuations.

4: Be safe.

founded 2 years ago
MODERATORS
DavideAndrea@discuss.tchncs.de
linker3000@discuss.tchncs.de
2
SBC UART debug troubleshooting (discuss.tchncs.de)
submitted 2 years ago by MaximGun@discuss.tchncs.de to c/askelectronics@discuss.tchncs.de
7 comments fedilink hide all child comments
 

Right to the point: On a BPI-R3, should connecting the UART debug pins directly to the appropriate pins on a DB9 USB serial adapter (rx->tx, tx->rx, gnd->gnd) work? Because I’m just getting a garbled mess in my serial console. I’ve tried all different baud rates. I’m using a high quality serial adapter (Keyspan Tripp Lite). I’ve tried on Linux and Windows. I assume I’m missing something stupid.

To make matters more annoying, I have a $5 almost certainly counterfeit USB serial adapter with USB on one end and DuPont connectors on the other end and it works fine, so at this point my problem is mostly academic. I would like to know what I’m doing wrong, though.

you are viewing a single comment's thread
view the rest of the comments
[–] th_in_gs@lemmy.sdf.org 2 points 2 years ago

I suspect your serial converter is expecting a ‘real’ RS232 signal, with its old-school now-weird voltage levels.

Your USB serial adapter is probably using 5V or 3V so-called ‘TTL’ signaling (which in the real world is mostly cross-compatible between 5V and 3V)

Good explanation here: https://www.sparkfun.com/tutorials/215