Hi,
We are developing a prototype containing a st25r3916b nfc reader. When the prototype is idle it goes into sleep mode and wakes up through the wakeup function.
When we actively poll for a card from our MCU we can read a UID from a distance of about 7cm (which is great for us). However, in wakeup mode with a trigger on inductive amplitude we have found a reliable detection distance of about 3 cm.
Is this to be expected? We found that by changing d_res of the tx_driver registry we can increase/decrease the amplitude of the field in wakeup mode. With low d_res values the wakeup mode triggers constantly, only at a d_res of 36.6% can we get a reliable card detection (at +- 3 cm) with a delta around 20. If we set the wakeup delta very high for low d_res values, it doesn't trigger constantly but then we have to hold the card really close to the antenna, defeating the purpose.
Are there other knobs we can turn to try to get reliable detection in wakeup mode from a greater distance? Ammod setting of the tx_driver register doesn't appear to do something.
As additional info: The ST25 C libs are used as a reference, the prototype is being built in Rust.
Thanks!
Sander
