Hello,
I start testing with the STEVAL-M25R16B Board and use this Time the self compiled Demo from ST
to test it. All works find.
Then i made an own PCB with Reader IC and Antenna on it and connect it to your MCU /Display Board.
The Board is connected to 3.3V, GND and the SPI / IRQ Lines.
The Antenna on my PCB is very small, only 21x26mm. Inductance measured with Siglent VNA 770nH.
( 0.5mm Track Width, 0.3mm Distance, 3 Turns)
The from your Tools calculated Values and my final Values after tuning differ..
My Result: L=270nH, Cemv 680pF, Cs 220pF, CTune 430pF, Rs 0.68R
I tuned the Circuit using my VNA and get a Reading Distance of about 25mm for 14443 Keyfobs and Cards
and about 6cm for ISO15693 Card.
This all works fine. Smith Chart looks perfect.
The Rx Voltage is about 1.5Vpp. The Voltage Divider Capacitors are 33p/120p.ST25R
Problem: Tags are working but in Emulate Mode i got no Reaction. With the Original Antenna (66x66mm) all is fine.
Need a little help how to go on...
