nRF52832 SPI voltage level switch circuit doesn't work

[kejun]

I met a big issue when implement the voltage level switch. I used nRF52832's SPI to communicate with an ECG sensor which has 1.8V SPI. The issue is that, 3.3V signal from nRF can switch to 1.8V in ECG side (such as ECG_SPI_SCLK and ECG_SPI_DOUT), but the 1.8V signal from ECG side CAN'T change to 3.3V in nRF side (such as ECG_SPI_DIN). TXS0108 has been used several times in my design and works very well. Is there any tricky I don't know in nRF application?

Thanks

[Roger Clark]

So are you saying that the voltage level shifter is not working for you ?

From what you've said the 1.8V SPI device is happy to accept CLK and MOSI but the nRF device can't accept the MISO signal as the voltage of a logic 1 is too low (as it would be 1.8V)

So all you need is the level shifter ic to effectively amplify the 1.8V from the EGC's MISO signal.