Working with 1-wire bus on nRF5340

Question

Hi there!

I'm trying to make the DS18b20 sensor work with nRF5340 under nRF Connect SDK.
I tried a Zephyr example (ncs/zephyr/samples/sensor/ds18b20), and, after some debugging, it worked fine, I got the temperature values.

After porting all 1-wire-related changes (device tree, prj.conf, changes in sources) to openthread/cli_mqtt-sn example, I get stuck. All that I got is a errors from the Zephyr 1-wire driver:
<err> w1_serial: tx_rx_error reset_present
[00:19:41.145,965] <err> DS18B20: No 1-Wire slaves connected

But, on the same board, with the same connections, the example from Zephyr works fine, so it is not about the not connected device.
I think UART1 is actually not working. I tried to connect an oscilloscope - and with vanilla Zephyr example, we got something on the 1-wire bus (which is actually uart RX and TX connected together), and with modified Nordic Openthread CLI example we have nothing on the bus:

Zephyr vanilla:
1-wire bus with Zephyr example

Modified Nordic:

I bring all 1-wire and uart-related stuff from the Zephyr example to the Nordic one, and .config files in build/zephyr look the same in UART 1 part.
But, for some reason, with the Nordic example, it doesn't work...

Can you please point me to a working Nordic nRF Connect-related example for a 1-wire bus, please?

Thanks in advance!

Dmitry Sysoletin · Answer

It seems like I've figured it out. With Zephyr (vanilla) firmware, pins 1.1 (port 1, pin 1) and 1.2 work normally, but with Nordic additions over Zephyr - looks like they're beginning to act differently. Here https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf5340%2Fchapters%2Fpin.html&cp=3_0_0_8_0 we have information about pin 1.02 and 1.03 are "specially designed for high-speed TWI". Despite that those pins work fine under Zephyr vanilla, Nordic additions seem to be changing those pins' mode. 
 Using different pins (1.11 and 1.12) solved my problem, now DS18b20 example works as part of the Nordic Openthread CLI example.