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PN512 7-bit I2C address

Question asked by Per Ekelund on Mar 23, 2018

I have a custom board for the PN512 that uses I2C addressing. I'm havning a hard time understanding a behaviour that im experiencing:

 

For I2C mode with "three" bit address, the A1 pin should be set HIGH as per datasheet:

 

 

A0 (EA) should be set low, as per datasheet:

 

Then the pins D5, D6 and D7 can be used to set the I2C address:

 



NXP sets the upper 4 bytes to 0101b. I am setting the remaining bits to 111b. So the 7-bit address should be 0101111b = 2F. Instead i detect a unstable I2C address on the bus after power up, either 3F or 07...The chip works in this condition anyway (on these addresses). In an attemt to understand this I changed the A0 (EA) pin to HIGH, and the chip registered on the expected address, 2F. I also changed around D4, D4 and D6 and was able to set addressed that was correct.

 

So it seems that th A0 (EA) pin is "flipped", it should be HIGH for the three bit addressing to work. That is inconsistent with the datasheet?

 

Thank you

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