FL-176 LF RFID RX (#248)

* pulldown ibutton pin during rfid read
* enable and handle COMP interrupts
* send events from comparator IRQ and handle in app
* manchester encode
* successfully read em4100
* read-emulate
* led

applications/lf-rfid/em4100.c

@@ -43,11 +43,13 @@ void prepare_data(uint32_t ID, uint32_t VENDOR, uint8_t* data) {
 
     data[63] = 0; // stop bit
 
+    /*
     printf("em data: ");
     for(uint8_t i = 0; i < 64; i++) {
         printf("%d ", data[i]);
     }
     printf("\n");
+    */
 }
 
 void em4100_emulation(uint8_t* data, GpioPin* pin) {
@@ -65,4 +67,4 @@ void em4100_emulation(uint8_t* data, GpioPin* pin) {
 
     gpio_write(pin, false);
     taskEXIT_CRITICAL();
-}
+}