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ST25RU3993 - reading registers

Question asked by Piotr Szwajda on Apr 10, 2018
Latest reply on May 7, 2018 by João Carlos Silva dos Santos



I'm building an UHF RFID reader using ST25RU3993 and I have a problem reading the registers. The idea is to connect the IC to NodeMCU or Arduino (both are programmed using Arduino IDE at this stage).

I connected MISO to MISO and MOSI to MOSI (I’m assuming there is an error in the datasheet Figure 3 p.15)

After enabling the IC (EN = 1) and waiting 1 second I try to read registers, but the IC does not respond to my SPI messages. I can see NCS, CLK and MOSI signals on the oscilloscope, but the MISO is always LOW. My code reads registers 0x00 to 0x24. The SPI was set to MODE1 (NodeMCU outputs data on rising edge and captures it on Falling edge as instructed in the datasheet p.15).

I tried different frequencies: 1kbps, 100kbps, 1Mbps, 2Mbps and 5Mbps.

According to the datasheet the IC should be in NORMAL mode and therefore the SPI communication should be possible after enabling the device.

I also see voltages at some of the pins (voltage regulators) so the device is powered up and is working. At least some parts of it. I have been assembling the board at home so there is a possibility that I fried it. I don’t want to buy a new chip before I’m sure this one is damaged.

Is there anything that I’m doing wrong? Did I forget about some procedure?

Please help!