I have this setup where a MinPro 3.3V is interfaced with a Mifare MFRC522 RFID reader. Power is from a 3.7V lipo cell via a Adafruit charger cum booster. ( https://www.adafruit.com/product/1944)
Problem is simple :
When i use the FTDI232 programming interface the MFRC522 reads very well. The Vcc to it is then 2.9V.
But at the same time if I power up from the LiPo cell, it just does not read. The Vcc to it is then 3.2V.
Is the PowerBoost module oscillator messing up things for the MFRC522 ?? Any other ideas ??