nrf: Add board definition for nRF52840-MDK-USB-Dongle.

ports/nrf/README.md

@@ -41,6 +41,7 @@ This is a port of MicroPython to the Nordic Semiconductor nRF series of chips.
   * [PCA10056](http://www.nordicsemi.com/eng/Products/nRF52840-Preview-DK)
   * [PCA10059](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-Dongle)
   * [Particle Xenon](https://docs.particle.io/xenon/)
+  * [nRF52840 MDK USB Dongle](boards/nrf52840-mdk-usb-dongle/README.md)
 * nRF9160
   * [PCA10090](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF9160-DK)
   * [Actinius Icarus](https://www.actinius.com/icarus)

ports/nrf/boards/memory.ld

@@ -1,14 +1,17 @@
 
 /* Flash layout: softdevice     | application     | filesystem */
 /* RAM layout:   softdevice RAM | application RAM */
-_sd_size       = DEFINED(_sd_size) ? _sd_size : 0;
+
+_ram_start     = DEFINED(_ram_start) ? _ram_start : 0x20000000;
+_flash_start   = DEFINED(_flash_start) ? _flash_start : 0;
+_sd_size       = DEFINED(_sd_size) ? _sd_size : _flash_start;
 _sd_ram        = DEFINED(_sd_ram)  ? _sd_ram : 0;
 _fs_size       = DEFINED(_fs_size) ? _fs_size : 64K; /* TODO: set to 0 if not using the filesystem */
 _app_size      = _flash_size - _sd_size - _fs_size;
 _app_start     = _sd_size;
 _fs_start      = _sd_size + _app_size;
 _fs_end        = _fs_start + _fs_size;
-_app_ram_start = 0x20000000 + _sd_ram;
+_app_ram_start = _ram_start + _sd_ram;
 _app_ram_size  = _ram_size - _sd_ram;
 _heap_start    = _ebss;
 _heap_end      = _ram_end - _stack_size;

ports/nrf/boards/nrf52840-mdk-usb-dongle/README.md

@@ -0,0 +1,49 @@
+nRF52840 MDK USB Dongle
+=======================
+
+The *[nRF52840 MDK USB
+Dongle](https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle)* is a small,
+low-cost development board in a USB dongle form-factor powered by an nRF52840
+with 1MB flash and 256KB RAM.
+
+This device is pre-installed with [Open
+Bootloader](https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle/programming/),
+allowing DFU upgrades over USB using Nordic [nRF
+Connect](https://www.nordicsemi.com/Software-and-tools/Development-Tools/nRF-Connect-for-desktop)
+or [nrfutil](https://github.com/NordicSemiconductor/pc-nrfutil/). To support
+Open Bootloader, the flash and memory layout must be adjusted slightly (details
+[here](https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial))
+from the typical nRF build; this board definition ensure the appropriate build
+configuration is used for MicroPython.
+
+
+Pinout
+------
+
+The [pinout
+diagram](https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle/#pinout-diagram)
+provides an overview of the available pins and their capabilities. All pins are
+available in MicroPython, using the pin numbers labelled in the diagram
+(excluding the leading port number, *P0*).
+
+The three LEDs are available either through the usual `Pin` mechanism - pins
+22-24 - or by `board.LED(n)` where n can be 1, 2 or 3.
+
+
+Build instructions
+------------------
+
+Follow the standard [nRF Port build instructions](../../README.md); but use
+`nrf52840-mdk-usb-dongle` as the value for `BOARD`:
+
+    make BOARD=nrf52840-mdk-usb-dongle
+
+The build artifacts will be created in `build-nrf52840-mdk-usb-dongle`. Once
+built, the easiest way to deploy to the device is to open `firmware.hex` using
+*nRF Connect* and select *Write*. Detailed instructions can be found on the
+[developer
+wiki](https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle/programming/). 
+
+**Note** that the regular method of deployment for the MicroPython nRF port
+(using `make deploy`) will *not* operate correctly and will overwrite the
+bootloader.

ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.h

@@ -0,0 +1,71 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Matt Trentini
+ *
+ * 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.
+ */
+
+#define MICROPY_HW_BOARD_NAME        "MDK-USB-DONGLE"
+#define MICROPY_HW_MCU_NAME          "NRF52840"
+#define MICROPY_PY_SYS_PLATFORM      "nrf52840-MDK-USB-Dongle"
+
+#define MICROPY_PY_MACHINE_UART      (1)
+#define MICROPY_PY_MACHINE_HW_PWM    (1)
+#define MICROPY_PY_MACHINE_HW_SPI    (1)
+#define MICROPY_PY_MACHINE_TIMER     (1)
+#define MICROPY_PY_MACHINE_RTCOUNTER (1)
+#define MICROPY_PY_MACHINE_I2C       (1)
+#define MICROPY_PY_MACHINE_ADC       (1)
+#define MICROPY_PY_MACHINE_TEMP      (1)
+
+#define MICROPY_HW_ENABLE_RNG        (1)
+
+#define MICROPY_HW_USB_CDC           (1)
+
+#define MICROPY_HW_HAS_LED           (1)
+#define MICROPY_HW_LED_COUNT         (3)
+#define MICROPY_HW_LED_PULLUP        (1)
+
+#define MICROPY_HW_LED1              (22)  // LED1 GREEN
+#define MICROPY_HW_LED2              (23)  // LED2 RED
+#define MICROPY_HW_LED3              (24)  // LED3 BLUE
+
+// UART config
+#define MICROPY_HW_UART1_RX          (7)
+#define MICROPY_HW_UART1_TX          (8)
+#define MICROPY_HW_UART1_CTS         (9)
+#define MICROPY_HW_UART1_RTS         (10)
+#define MICROPY_HW_UART1_HWFC        (1)
+
+// SPI0 config
+#define MICROPY_HW_SPI0_NAME         "SPI0"
+
+#define MICROPY_HW_SPI0_SCK          (19)
+#define MICROPY_HW_SPI0_MOSI         (20)
+#define MICROPY_HW_SPI0_MISO         (21)
+
+#define MICROPY_HW_PWM0_NAME         "PWM0"
+#define MICROPY_HW_PWM1_NAME         "PWM1"
+#define MICROPY_HW_PWM2_NAME         "PWM2"
+#define MICROPY_HW_PWM3_NAME         "PWM3"
+
+#define HELP_TEXT_BOARD_LED          "1,2,3"

ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.mk

@@ -0,0 +1,7 @@
+MCU_SERIES = m4
+MCU_VARIANT = nrf52
+MCU_SUB_VARIANT = nrf52840
+SOFTDEV_VERSION = 6.1.1
+LD_FILES += boards/nrf52840-mdk-usb-dongle/nrf52840_open_bootloader.ld boards/nrf52840_1M_256k.ld
+
+NRF_DEFINES += -DNRF52840_XXAA

ports/nrf/boards/nrf52840-mdk-usb-dongle/nrf52840_open_bootloader.ld

@@ -0,0 +1,2 @@
+_ram_start   = 0x20000008;
+_flash_start = 0x1000;

ports/nrf/boards/nrf52840-mdk-usb-dongle/pins.csv

@@ -0,0 +1,17 @@
+P2,P2,ADC1_CH0
+P3,P3,ADC1_CH1
+P4,P4,ADC1_CH2
+P5,P5,ADC1_CH3
+P6,P6
+P7,P7
+P8,P8
+P9,P9
+P10,P10
+USER,P18,P18
+P19,P19
+P20,P20
+P21,P21
+LED_G,P22,P22
+LED_R,P23,P23
+LED_B,P24,P24
+P25,P25