Adding support for the 'Plus' board variant of SeeedStudio XIAO nrf52840, works with Sense variants as well (#5479)

* adding support for SeeedStudio XIAO BLE Plus and Sense Plus boards;

* adjusting definitions for UARTs on XIAO BLE Plus;

* fixed buid tag on XIAO BLE Plus;

* tested by building some examples; fixed UART nomenclature;

* added xiao-ble-plus to GNUmakefile smoketests;

src/machine/board_xiao-ble-plus.go

@@ -0,0 +1,136 @@
+//go:build xiao_ble_plus
+
+// This file contains the pin mappings for the Seeed XIAO BLE nRF52840 [Plus, Sense Plus] boards.
+//
+// Seeed XIAO BLE is an ultra-small size, ultra-low power Bluetooth development board based on the Nordic nRF52840.
+// It features an onboard Bluetooth antenna, onboard battery charging chip, and 21*17.5mm thumb size, which makes it ideal for IoT projects.
+//
+// Seeed XIAO BLE nRF52840 Sense is a tiny Bluetooth LE development board designed for IoT and AI applications.
+// It features an onboard antenna, 6 Dof IMU, microphone, all of which make it an ideal board to run AI using TinyML and TensorFlow Lite.
+//
+// SoftDevice (s140v7) is pre-flashed on this board already.
+// See https://github.com/tinygo-org/bluetooth
+//
+// - https://www.seeedstudio.com/Seeed-XIAO-BLE-nRF52840-p-5201.html
+// - https://www.seeedstudio.com/Seeed-XIAO-BLE-Sense-nRF52840-p-5253.html
+// - https://www.seeedstudio.com/Seeed-Studio-XIAO-nRF52840-Sense-Plus-p-6360.html
+//
+// - https://wiki.seeedstudio.com/XIAO_BLE/
+// - https://github.com/Seeed-Studio/ArduinoCore-mbed/tree/master/variants/SEEED_XIAO_NRF52840_SENSE
+package machine
+
+const HasLowFrequencyCrystal = true
+
+// Digital Pins
+const (
+	D0  Pin = P0_02
+	D1  Pin = P0_03
+	D2  Pin = P0_28
+	D3  Pin = P0_29
+	D4  Pin = P0_04
+	D5  Pin = P0_05
+	D6  Pin = P1_11
+	D7  Pin = P1_12
+	D8  Pin = P1_13
+	D9  Pin = P1_14
+	D10 Pin = P1_15
+	D11 Pin = P0_15
+	D12 Pin = P0_19
+	D13 Pin = P1_01
+	D14 Pin = P0_09
+	D15 Pin = P0_10
+	D16 Pin = P0_31
+	D17 Pin = P1_03
+	D18 Pin = P1_05
+	D19 Pin = P1_07
+)
+
+// Analog pins
+const (
+	A0 Pin = P0_02
+	A1 Pin = P0_03
+	A2 Pin = P0_28
+	A3 Pin = P0_29
+	A4 Pin = P0_04
+	A5 Pin = P0_05
+)
+
+// Onboard LEDs
+const (
+	LED       = LED_CHG
+	LED1      = LED_RED
+	LED2      = LED_GREEN
+	LED3      = LED_BLUE
+	LED_CHG   = P0_17
+	LED_RED   = P0_26
+	LED_GREEN = P0_30
+	LED_BLUE  = P0_06
+)
+
+// UART pins
+const (
+	UART_RX_PIN  = P1_12
+	UART_TX_PIN  = P1_11
+	UART1_RX_PIN = P0_09
+	UART1_TX_PIN = P0_10
+)
+
+// I2C pins
+const (
+	// Defaults to internal
+	SDA_PIN = SDA1_PIN
+	SCL_PIN = SCL1_PIN
+
+	// I2C0 (external) pins
+	SDA0_PIN = P0_04
+	SCL0_PIN = P0_05
+
+	// I2C1 (internal) pins
+	SDA1_PIN = P0_07
+	SCL1_PIN = P0_27
+)
+
+// I2S pins
+const (
+	I2S_SCK_PIN = P0_19
+	I2S_WS_PIN  = P1_01
+	I2S_SD_PIN  = P0_15
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN = P1_13
+	SPI0_SDO_PIN = P1_14
+	SPI0_SDI_PIN = P1_15
+)
+
+// Peripherals
+const (
+	LSM_PWR = P1_08 // IMU (LSM6DS3TR) power
+	LSM_INT = P0_11 // IMU (LSM6DS3TR) interrupt
+
+	MIC_PWR = P1_10 // Microphone (MSM261D3526H1CPM) power
+	MIC_CLK = P1_00
+	MIC_DIN = P0_16
+)
+
+// NFC pins
+const (
+	NFC1_PIN = P0_09
+	NFC2_PIN = P0_10
+)
+
+// USB CDC identifiers
+const (
+	usb_STRING_PRODUCT      = "XIAO nRF52840 Sense"
+	usb_STRING_MANUFACTURER = "Seeed"
+)
+
+var (
+	usb_VID uint16 = 0x2886
+	usb_PID uint16 = 0x8045
+)
+
+var (
+	DefaultUART = UART0
+)