ST25R3914-AQWT MISO signal is shifted to 1.2V

[PSHAH.1]

I am Using ST25R3914-AQWT NFC chip as a Slave Device and Renesas RL78 as Master device for SPI communication. 

When I tried to interface both controller MISO signal is shifted to 1.2V

[Tesla DeLorean]

Would suggest you're wiring it wrong.Show a wiring diagram or schematic. ​

[Travis Palmer · Accepted solution]

Hello PSHAH.1,

A schematic diagram would be indeed helpful.

Our chip sets typically have the VDD_IO supply. It sources the internal level shifter. VDD_IO should be at the MCUs SPI level.

e.g. if the MCU is running at 3.3V, also VDD_IO should be put to 3.3V. VDD of the ST25R can be set to any value specified in the datasheet.

If the MCU is supplied via 3.3V and VDD_IO is driven by 5V, it could explain a shift in the MISO signal.

please let me know, if this helped!

BR Travis

[PSHAH.1]

Thank you for reply this issue is resolved. there was some stack issue now SPI is working perfectly ok