Hello, 1) With your SparkFunThingPlus-STM32F405 card, the PB12 pin (cardDetect) is not connected to reader card pin 10.  2) There is a short circuit with the card reader double pin 10  Error in the card reader manufacturer's datasheet and red correction  Erase thermal-break, pin 10 will no longer be grounded  Thanks to make a revision of this board