mimxrt: Define UART 0 on MIMXRT boards.

UART 0 is attached to the Debug USB port. The settings are
115200 Baud, 8N1.
For MIMXRT1010_EVK this is identical to UART1. For the other boards,
this is an additional UART.

ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.h

@@ -9,12 +9,13 @@
 #define MICROPY_HW_NUM_PIN_IRQS (2 * 32)
 
 // Define mapping logical UART # to hardware UART #
-// LPUART1 on D0/D1 -> 1
-// LPUART3 on A0/D4 -> 3
-// LPUART4 on D6/D7 -> 2
+// LPUART1 on USB_DBG  -> 0
+// LPUART1 on D0/D1    -> 1
+// LPUART3 on A0/D4    -> 3
+// LPUART4 on D6/D7    -> 2
 
 #define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
-#define MICROPY_HW_UART_INDEX   { 0, 1, 4 }
+#define MICROPY_HW_UART_INDEX   { 1, 1, 4, 3 }
 
 #define IOMUX_TABLE_UART \
     { IOMUXC_GPIO_10_LPUART1_TXD }, { IOMUXC_GPIO_09_LPUART1_RXD }, \

ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.h

@@ -10,16 +10,17 @@
 #define MICROPY_HW_NUM_PIN_IRQS (3 * 32)
 
 // Define mapping logical UART # to hardware UART #
-// RX/TX   HW-UART    Logical UART
-// D3/D5   LPUART1    Not usable, Since D3 is blocked.
-// D0/D1   LPUART2 -> 1
-// D6/D9   LPUART3 -> 2
-// D10/D12 LPUART5 -> 3
-// D14/D15 LPUART8 -> 4
-// A0/A1   LPUART4 -> 5
+// RX/TX      HW-UART    Logical UART
+// DEBUG USB  LPUART1 -> 0
+// D3/D5      LPUART1    Not usable, Since D3 is blocked.
+// D0/D1      LPUART2 -> 1
+// D6/D9      LPUART3 -> 2
+// D10/D12    LPUART5 -> 3
+// D14/D15    LPUART8 -> 4
+// A0/A1      LPUART4 -> 5
 
 #define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
-#define MICROPY_HW_UART_INDEX   { 0, 2, 3, 5, 8, 4 }
+#define MICROPY_HW_UART_INDEX   { 1, 2, 3, 5, 8, 4 }
 
 #define IOMUX_TABLE_UART \
     { IOMUXC_GPIO_AD_B0_06_LPUART1_TX }, { IOMUXC_GPIO_AD_B0_07_LPUART1_RX }, \

ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.h

@@ -9,16 +9,17 @@
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
 // Define mapping logical UART # to hardware UART #
-// LPUART3 on D0/D1  -> 1
-// LPUART2 on D7/D6  -> 2
-// LPUART6 on D8/D9  -> 3
-// LPUART8 on A1/A0  -> 4
+// LPUART1 on USB_DBG  -> 0
+// LPUART3 on D0/D1    -> 1
+// LPUART2 on D7/D6    -> 2
+// LPUART6 on D8/D9    -> 3
+// LPUART8 on A1/A0    -> 4
 
 #define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
-#define MICROPY_HW_UART_INDEX   { 0, 3, 2, 6, 8 }
+#define MICROPY_HW_UART_INDEX   { 1, 3, 2, 6, 8 }
 
 #define IOMUX_TABLE_UART \
-    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B0_12_LPUART1_TX }, { IOMUXC_GPIO_AD_B0_13_LPUART1_RX }, \
     { IOMUXC_GPIO_AD_B1_02_LPUART2_TX }, { IOMUXC_GPIO_AD_B1_03_LPUART2_RX }, \
     { IOMUXC_GPIO_AD_B1_06_LPUART3_TX }, { IOMUXC_GPIO_AD_B1_07_LPUART3_RX }, \
     { 0 }, { 0 }, \

ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.h

@@ -9,16 +9,17 @@
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
 // Define mapping logical UART # to hardware UART #
-// LPUART3 on D0/D1  -> 1
-// LPUART2 on D7/D6  -> 2
-// LPUART6 on D8/D9  -> 3
-// LPUART8 on A1/A0  -> 4
+// LPUART1 on USB_DBG  -> 0
+// LPUART3 on D0/D1    -> 1
+// LPUART2 on D7/D6    -> 2
+// LPUART6 on D8/D9    -> 3
+// LPUART8 on A1/A0    -> 4
 
 #define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
-#define MICROPY_HW_UART_INDEX   { 0, 3, 2, 6, 8 }
+#define MICROPY_HW_UART_INDEX   { 1, 3, 2, 6, 8 }
 
 #define IOMUX_TABLE_UART \
-    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B0_12_LPUART1_TX }, { IOMUXC_GPIO_AD_B0_13_LPUART1_RX }, \
     { IOMUXC_GPIO_AD_B1_02_LPUART2_TX }, { IOMUXC_GPIO_AD_B1_03_LPUART2_RX }, \
     { IOMUXC_GPIO_AD_B1_06_LPUART3_TX }, { IOMUXC_GPIO_AD_B1_07_LPUART3_RX }, \
     { 0 }, { 0 }, \

ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.h

@@ -9,16 +9,17 @@
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
 // Define mapping logical UART # to hardware UART #
-// LPUART3 on D0/D1  -> 1
-// LPUART2 on D7/D6  -> 2
-// LPUART6 on D8/D9  -> 3
-// LPUART8 on A1/A0  -> 4
+// LPUART1 on USB_DBG  -> 0
+// LPUART3 on D0/D1    -> 1
+// LPUART2 on D7/D6    -> 2
+// LPUART6 on D8/D9    -> 3
+// LPUART8 on A1/A0    -> 4
 
 #define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
-#define MICROPY_HW_UART_INDEX   { 0, 3, 2, 6, 8 }
+#define MICROPY_HW_UART_INDEX   { 1, 3, 2, 6, 8 }
 
 #define IOMUX_TABLE_UART \
-    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B0_12_LPUART1_TX }, { IOMUXC_GPIO_AD_B0_13_LPUART1_RX }, \
     { IOMUXC_GPIO_AD_B1_02_LPUART2_TX }, { IOMUXC_GPIO_AD_B1_03_LPUART2_RX }, \
     { IOMUXC_GPIO_AD_B1_06_LPUART3_TX }, { IOMUXC_GPIO_AD_B1_07_LPUART3_RX }, \
     { 0 }, { 0 }, \

ports/mimxrt/machine_uart.c

@@ -269,7 +269,7 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
 
     // Get UART bus.
     int uart_id = mp_obj_get_int(args[0]);
-    if (uart_id < 1 || uart_id > MICROPY_HW_UART_NUM) {
+    if (uart_id < 0 || uart_id > MICROPY_HW_UART_NUM || uart_index_table[uart_id] == 0) {
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("UART(%d) doesn't exist"), uart_id);
     }
 
@@ -286,11 +286,15 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
     LPUART_GetDefaultConfig(&self->config);
 
     // Configure board-specific pin MUX based on the hardware device number.
-    lpuart_set_iomux(uart_hw_id);
+    bool uart_present = lpuart_set_iomux(uart_hw_id);
 
-    mp_map_t kw_args;
-    mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
-    return machine_uart_init_helper(self, n_args - 1, args + 1, &kw_args);
+    if (uart_present) {
+        mp_map_t kw_args;
+        mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
+        return machine_uart_init_helper(self, n_args - 1, args + 1, &kw_args);
+    } else {
+        return mp_const_none;
+    }
 }
 
 // uart.init(baud, [kwargs])