is there a difference between ST25R3911 and ST25R3911B?

[SD.5]

We are moving from ST25R3911 to the latest version ST25R3911B with the firmware and the other circuitry remains the same. But we are seeing the reduction in operating distance for the cards.

[XP.1]

Hi Ulysses,

for measuring Phase we have used the Measure-Phase-Direct Command 0xD9 and read out the A/D output register 20H

Regards

Xavier

[Ulysses HERNIOSUS · Accepted solution]

Hi Xavier,

this procedure sounds right, I assume you delay sufficiently/wait for the termination interrupt in between?!

Any chance that you can do smith charts as in AN4914 for some trim values?

The AN4914 presents also that the similar algorithms can easily be implemented in SW (measuring 16 points and picking the best - I recommend the one with highest amplitude). Could this be an acceptable change which solves the issue for you?

I am suspecting a minor change of behavior of the internal algorithm (between ST25R3911 and ST25R3911B) when the target phase is not reachable, but would need to do more investigation here.

Regards, Ulysses