Turris MOX: which pins are for UART

MOX hardware
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1

I apologize for OT, which pins should I connect to Hacker Pack / serial console?

2

Hello,

You can take a look at our documentation, where we have GPIO layout together with photo, how it should be connected to Turris MOX.

Be aware that the serial cable, which was for Turris Omnia cannot be used!

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3

Perfect, thank you, I have Hacker Pack for MOX.
And what pin I can connect to when I have a +POE module connected at the same time?

4

Of course, it is still possible to connect a serial console with the use of a PoE module. The pins for this console are also on the PoE module. Thank you for your feedback and we will add this information to our documentation.

5

Ping. I just (finally!) received my Mox with PoE module and I have no clue how to connect the UART. It looks like the header on the PoE module is not documented at all.

Also what exactly do you mean by this sentence?

Use 6 pin cable. Always connect the red Vin wire for proper operation:

Red wireļ¼š V in , Black wireļ¼š GND , White wireļ¼š RXD , Green wireļ¼š TXD , Yellow wireļ¼š RTS , Blue wireļ¼š CTS

Since the red wire is typically hardwired to +5V VBUS on many USB-to-serial cables, connecting it can easily result is frying 1V8 MOX. I would rather recommend against connecting the red cable at all, just like the photo shows. And why do you insist on using 6pin cable if only 3 wires are connected?

6

Thanks for bringing this up, fixed the unfortunate wording.

Regarding the PoE pinout, no idea at the moment, will get back to you on Monday.

7

Thank you, but this is still insufficient:

Where to? On the pinout, there is no signal named Vin. Connecting it to +1V8 could possibly fry Mox (as 5 volts can be coming from the USB), connecting to +12V will probably fry the USB cable as it is rated for 5 volts max.

I propose this text:

Take extra care when connecting the red wire. On some cables, this is directly connected to +5V USB power. In that case, keep it disconnected, as connecting it will fry the Mox. However on some cables like 6-wire USB cable supplied in some hacker packs, the red wire powers the cable itself and has to be connected to a +1V8 pin.

8

I wanted to figure out why the MOX isnā€™t netbooting, and I thought Iā€™d watch what it spits out to the serial link.

I only have a 3V USB->UART cable at home, so I built this circuit that should translate the 3V levels to 1.8V: https://forum.odroid.com/viewtopic.php?f=53&t=4758 (with the only difference that I used BC547C transistor). I connected the connector according to the guide at https://doc.turris.cz/doc/en/troubleshooting/serial_link#turris_mox to pins 5, 6, 13 and 14 (yes, I had to connect the red wire).

But as soon as I connect it and boot up MOX, both white and red cable show 1.8 V, green shows 1.3 V, and it never changes regardless of what I type in the terminal. Also, the terminal remains blank.

I connect to the terminal using command screen /dev/ttyUSB3 9600.

So whatā€™s wrong here? Do I expect MOX to do something itā€™s not designed to do? Or do I just need to buy a proper 1.8V USB->UART cable? If so, do you have any recommendations where to get it in Prague?

9

OK, Iā€™ve reverse-engineered that and put it into the community docs.

BTW, since MOXes are being shipped already, could we get the full schematics of it?

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10

Can anyone point at some USB serial devices (on amazon and/or aliexpress) that are 1.8V ?

11

TTL-232RG-VREG1V8-WE from FTDI is what you want if you want to go the safe but expensive way. There are, of course, some cheap chinese thingies, but trust them (e.g. Given the pinout details for the UART, can I assume 3.3 V as voltage?).

12

I bought: https://www.amazon.ca/gp/product/B07TXVRQ7V/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 and it worked great. The colours on the supplied ribbon cable are daft, so look at them carefully. You probably want to align the RED with VCC side. That lines up ā€œWHITEā€ correctly, but then you wind up with Black for TX, and Brown for GND, which as I say, is a daft choice of this maker. Or use your own jumpers or the right colour, but mine were annoyingly short, so I used theirs.

I also ordered: https://www.amazon.ca/gp/product/B085ZHQ496/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 which is 1/5 the price, but I havenā€™t received it yet.