PN7150 with Arduino connection error

[NZBI226]

We're making a design with PN7150 and Arduino to detect NFC tag. I have worked the schematic out according to typical application schematic in PN7150 datasheet.

When I2CADR0 and I2CARDR1 are connected to ground, serial monitor showed two i2c addresses 0x28 and 0x7C at the first scanning. When I2CADR0 and I2CARDR1 are connected to PVDD( 3,3V), serial monitor showed two i2c addresses 0x2B and 0x7C at the first scanning. And then only 0x7C can be scanned. But 7-bits slave addresses of PN7150 are from 0x28 to 0x2B. After running DetecTags example of PN7150 arduino library, at the initialization we got the error " Error while setting up the mode, check connections."

https://github.com/ElectronicCats/ElectronicCats-PN7150/tree/master/examples/DetectTags

I have also tested the voltage of all the pins. In the principle, VDD(PAD) should be 3,3V or 1,8V. But when 3,3V voltage didn't connect to VDD(PAD), the voltage of VDD(PAD) is already around 4,5V.

1. Are all the connections of my schematic correct?
2.Which reasons result in the false voltage on VDD(PAD)?
3. Is PN7150 after the first scanning in Power Off Mode?

Thanks in advance and any advice is welcome.

[Fabian_R]

Hello, thank you for using our products.

We do recommend you please explore the possibility of using our boards to create your solution, keep in mind that Arduino is an 8-bit MCU, which might be missing the last bit of the I2C address. As you can see in the next lines, the reason you are getting 0x28 is that you are missing the last bit. The same case for 0x2B.

(I2CADR0 and I2CADR1) = GND

0x50 -> 101 0000

0x28 -> 10 1000

(I2CADR0 and I2CADR1 )= 3V3

0x56 -> 1010110

0x2B -> 101011

Regarding the VDD(PAD) issue, I'll first have to know if you are using our PN7150 Evaluation board and, be sure that the connections are as we recommend in our AN11841 Section 4.