adding raytac mdbt50q rx dongle support

https://github.com/adafruit/Adafruit_nRF52_Arduino/pull/328

src/boards/raytac_mdbt50q_rx/board.h

@@ -0,0 +1,72 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef RAYTAC_MDBT50Q_RX_H
+#define RAYTAC_MDBT50Q_RX_H
+
+#define _PINNUM(port, pin)    ((port)*32 + (pin))
+
+/*------------------------------------------------------------------*/
+/* LED
+ *------------------------------------------------------------------*/
+#define LEDS_NUMBER       1
+#define LED_PRIMARY_PIN   _PINNUM(1, 13)
+#define LED_STATE_ON      0
+
+/*------------------------------------------------------------------*/
+/* BUTTON
+ *------------------------------------------------------------------*/
+#define BUTTONS_NUMBER  2
+
+#define BUTTON_1       _PINNUM(0, 15)
+#define BUTTON_2       _PINNUM(0, 10)
+#define BUTTON_PULL    NRF_GPIO_PIN_PULLUP
+
+/*------------------------------------------------------------------*/
+/* UART
+ *------------------------------------------------------------------*/
+#define RX_PIN_NUMBER  20
+#define TX_PIN_NUMBER  17
+#define CTS_PIN_NUMBER 15
+#define RTS_PIN_NUMBER 13
+#define HWFC           false
+
+// Used as model string in OTA mode
+#define BLEDIS_MANUFACTURER  "Raytac"
+#define BLEDIS_MODEL         "MDBT50Q-RX"
+
+//--------------------------------------------------------------------+
+// USB
+//--------------------------------------------------------------------+
+#define USB_DESC_VID           0x239A
+#define USB_DESC_UF2_PID       0x0029
+#define USB_DESC_CDC_ONLY_PID  0x002A
+
+//------------- UF2 -------------//
+#define UF2_PRODUCT_NAME  "Raytac MDBT50Q-RX"
+#define UF2_VOLUME_LABEL  "MDBT50QBOOT"
+#define UF2_BOARD_ID      "nRF52840-MDBT50Q_RX-v1"
+#define UF2_INDEX_URL     "https://www.raytac.com/product/ins.php?index_id=89"
+
+#endif // RAYTAC_MDBT50Q_RX_H

src/boards/raytac_mdbt50q_rx/board.mk

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+MCU_SUB_VARIANT = nrf52840