Microcontroller does not receive data via UART after the level converter

[backstreet.devisor]

Good Day.

I am using a custom board with a nRF52840 (3.3V) microcontroller. GNSS RYS8830 (1.8V) is installed on the board and connected to the microcontroller via UART1 through a transistor level converter (see schematic). The data from the microcontroller successfully reaches the GNSS.  But the responses from the GNSS do not reach the microcontroller on pin P0.17 (although they are there, I can see this through the connected TTL to the computer). The strange thing is that after the transistor on the P0.17 line the voltage is 2V, although it should be 3.3V.

Could you please advise me what could be the problem?

I am programming a custom board via nRF52840DK. 

Thanks.

[Jared]

Hi,

Can you disconnect the TTL to the PC and probe P0.17 and P0.18 to either a logical analyzer or a oscilloscope, what do you measure? How high are the amplitude of the serial signals now?

Btw, you can always decrease the GPIO signals on the nRF52840 by adjusting VDD to 1V8 by setting REGOUT0 to 1V8. The condition is that you're using the board in high voltage mode,

regards

Jared 

[backstreet.devisor]

Thank you Jared.

Can you please tell me if I can set only the UART pins to 1.8V?

[Jared]

Hi,

That is not possible unfortunately, all GPIOs share the same voltage level.

regards

Jared