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PSHAH.1
PSHAH.1
Associate
August 6, 2022
Solved

ST25R3914-AQWT MISO signal is shifted to 1.2V

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

This topic has been closed for replies.
Travis Palmer
Travis PalmerBest answer
ST Employee
August 30, 2022

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

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3 replies

Tesla DeLorean
Tesla DeLorean
Guru
August 6, 2022

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

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Travis Palmer
Travis PalmerBest answer
ST Employee
August 30, 2022

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
PSHAH.1Author
Associate
September 27, 2022

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

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