diff --git a/software/firmware_module/module_rev3/src/mctrl.c b/software/firmware_module/module_rev3/src/mctrl.c
index 94ebdaf..90286bb 100644
--- a/software/firmware_module/module_rev3/src/mctrl.c
+++ b/software/firmware_module/module_rev3/src/mctrl.c
@@ -173,7 +173,7 @@ ISR(TIMER1_COMPA_vect)
                 absolute_pos -= STEPS_PER_REV;
             }
             // detect home position
-            if ((PIND & (1 << PD3)) == 0)
+            if ((PIND & (1 << PD4)) == 0)
             {
                 if (lastSens == 0)
                 {
diff --git a/software/firmware_module/module_rev3/src/rs458.c b/software/firmware_module/module_rev3/src/rs458.c
index 5b8bc18..2fb86a0 100644
--- a/software/firmware_module/module_rev3/src/rs458.c
+++ b/software/firmware_module/module_rev3/src/rs458.c
@@ -12,9 +12,9 @@
 void rs485_init()
 {
     // init I/O
-    DDRD &= ~(1 << PD0);                          // BUS_DIR & TX is OUTPUT
+    DDRD &= ~(1 << PD0);                          // RX is INPUT
     DDRD |= (1 << PD3) | (1 << PD2) | (1 << PD1); // BUS_DIR & TX is OUTPUT
-    PORTD &= 0x07;                                // clear PD0-PD4
+    PORTD &= 0xE0;                                // clear PD0-PD4
     // init UART
     UBRRH = (BAUDRATE >> 8);
     UBRRL = BAUDRATE;                                    // set baud rate