diff --git a/variants/grand_central_m4/variant.cpp b/variants/grand_central_m4/variant.cpp
index 9af51600..65874f7e 100644
--- a/variants/grand_central_m4/variant.cpp
+++ b/variants/grand_central_m4/variant.cpp
@@ -53,16 +53,15 @@ const PinDescription g_APinDescription[]=
   // 13 (LED)
   { PORTB,  1, PIO_DIGITAL, PIN_ATTR_PWM_E, No_ADC_Channel, TC7_CH1, TC7_CH1,  EXTERNAL_INT_1 },
 
-  // 14..21 - Analog pins
-  // --------------------
-  { PORTA,  2, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel0, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 },
-  { PORTA,  5, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel5, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 },
-  { PORTB,  3, PIO_ANALOG, (PIN_ATTR_ANALOG|PIN_ATTR_PWM_E), ADC_Channel15, TC6_CH1, TC6_CH1, EXTERNAL_INT_3 },
-  { PORTC,  0, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel10, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_0 },
-  { PORTC,  1, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel11, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_1 },
-  { PORTC,  2, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel4, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 },
-  { PORTC,  3, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel5, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_3 },
-  { PORTB,  4, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel6, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4 },
+  // 14..21 - UARTS
+  { PORTB,  16, PIO_SERCOM, PIN_ATTR_PWM_E, No_ADC_Channel, TC6_CH0, TC6_CH0, EXTERNAL_INT_0 }, // UART3_TX
+  { PORTB,  17, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_1 }, // UART3_RX
+  { PORTC,  22, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, // UART2_TX
+  { PORTC,  23, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, // UART2_RX
+  { PORTB,  12, PIO_SERCOM, PIN_ATTR_PWM_F, No_ADC_Channel, TCC3_CH0, NOT_ON_TIMER, EXTERNAL_INT_12 }, // UART1_TX
+  { PORTB,  13, PIO_SERCOM, PIN_ATTR_PWM_F, No_ADC_Channel, TCC3_CH1, NOT_ON_TIMER, EXTERNAL_INT_13 }, // UART1_RX
+  { PORTB,  20, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4 }, //same as SDA
+  { PORTB,  21, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 }, //same as SCL
 
   // 22..53 - Extra Digital Pins
   // ----------------------
@@ -127,15 +126,16 @@ const PinDescription g_APinDescription[]=
   { PORTD,  8, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER,  EXTERNAL_INT_3 }, // MOSI
   { PORTD,  9, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER,  EXTERNAL_INT_4 }, // SCK
 
-  //67..74 - UARTS
-  { PORTB,  16, PIO_SERCOM, PIN_ATTR_PWM_E, No_ADC_Channel, TC6_CH0, TC6_CH0, EXTERNAL_INT_0 }, // UART3_TX
-  { PORTB,  17, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_1 }, // UART3_RX
-  { PORTC,  22, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, // UART2_TX
-  { PORTC,  23, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_6 }, // UART2_RX
-  { PORTB,  12, PIO_SERCOM, PIN_ATTR_PWM_F, No_ADC_Channel, TCC3_CH0, NOT_ON_TIMER, EXTERNAL_INT_12 }, // UART1_TX
-  { PORTB,  13, PIO_SERCOM, PIN_ATTR_PWM_F, No_ADC_Channel, TCC3_CH1, NOT_ON_TIMER, EXTERNAL_INT_13 }, // UART1_RX
-  { PORTB,  20, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4 }, //same as SDA
-  { PORTB,  21, PIO_SERCOM, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 }, //same as SCL
+  // 67..74 - Analog pins
+  // --------------------
+  { PORTA,  2, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel0, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 },
+  { PORTA,  5, PIO_ANALOG, PIN_ATTR_ANALOG, ADC_Channel5, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_5 },
+  { PORTB,  3, PIO_ANALOG, (PIN_ATTR_ANALOG|PIN_ATTR_PWM_E), ADC_Channel15, TC6_CH1, TC6_CH1, EXTERNAL_INT_3 },
+  { PORTC,  0, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel10, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_0 },
+  { PORTC,  1, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel11, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_1 },
+  { PORTC,  2, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel4, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_2 },
+  { PORTC,  3, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel5, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_3 },
+  { PORTB,  4, PIO_ANALOG, PIN_ATTR_ANALOG_ALT, ADC_Channel6, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_4 },
 
   // 75..76 - RX/TX LEDS
   // --------------------
diff --git a/variants/grand_central_m4/variant.h b/variants/grand_central_m4/variant.h
index 61c2d3da..a91025a9 100644
--- a/variants/grand_central_m4/variant.h
+++ b/variants/grand_central_m4/variant.h
@@ -93,7 +93,7 @@ extern "C"
 /*
  * Analog pins
  */
-#define PIN_A0               (14ul)
+#define PIN_A0               (67ul)
 #define PIN_A1               (PIN_A0 + 1)
 #define PIN_A2               (PIN_A0 + 2)
 #define PIN_A3               (PIN_A0 + 3)
@@ -152,22 +152,22 @@ static const uint8_t ATN = PIN_ATN;
 #define PAD_SERIAL1_RX       (SERCOM_RX_PAD_1)
 
 // Serial2
-#define PIN_SERIAL2_RX       (72ul)
-#define PIN_SERIAL2_TX       (71ul)
+#define PIN_SERIAL2_RX       (19ul)
+#define PIN_SERIAL2_TX       (18ul)
 #define PAD_SERIAL2_TX       (UART_TX_PAD_0)
 #define PAD_SERIAL2_RX       (SERCOM_RX_PAD_1)
 #define SERCOM_SERIAL2		 sercom4
 
 // Serial3
-#define PIN_SERIAL3_RX       (70ul)
-#define PIN_SERIAL3_TX       (69ul)
+#define PIN_SERIAL3_RX       (17ul)
+#define PIN_SERIAL3_TX       (16ul)
 #define PAD_SERIAL3_TX       (UART_TX_PAD_0)
 #define PAD_SERIAL3_RX       (SERCOM_RX_PAD_1)
 #define SERCOM_SERIAL3		 sercom1
 
 // Serial4
-#define PIN_SERIAL4_RX       (68ul)
-#define PIN_SERIAL4_TX       (67ul)
+#define PIN_SERIAL4_RX       (15ul)
+#define PIN_SERIAL4_TX       (14ul)
 #define PAD_SERIAL4_TX       (UART_TX_PAD_0)
 #define PAD_SERIAL4_RX       (SERCOM_RX_PAD_1)
 #define SERCOM_SERIAL4		 sercom5