Add board support for keithp.com SnekBoard

This is another SAMDG2118A design with built-in 9V motor controllers
that are designed to be used with Lego PowerFunctions devices.

Signed-off-by: Keith Packard <keithp@keithp.com>

ports/atmel-samd/boards/snekboard/board.c

@@ -0,0 +1,38 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Scott Shawcroft 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.
+ */
+
+#include "boards/board.h"
+
+void board_init(void)
+{
+}
+
+bool board_requests_safe_mode(void) {
+    return false;
+}
+
+void reset_board(void) {
+}

ports/atmel-samd/boards/snekboard/mpconfigboard.h

@@ -0,0 +1,39 @@
+#define MICROPY_HW_BOARD_NAME "Keith.com SnekBoard"
+#define MICROPY_HW_MCU_NAME "samd21g18"
+
+#define MICROPY_HW_LED_STATUS   (&pin_PA02)
+
+#define MICROPY_HW_NEOPIXEL (&pin_PB11)
+
+#define SPI_FLASH_MOSI_PIN          &pin_PB22
+#define SPI_FLASH_MISO_PIN          &pin_PB03
+#define SPI_FLASH_SCK_PIN           &pin_PB23
+#define SPI_FLASH_CS_PIN            &pin_PA27
+
+// These are pins not to reset.
+#define MICROPY_PORT_A        (PORT_PB11)
+#define MICROPY_PORT_B        ( 0 )
+#define MICROPY_PORT_C        ( 0 )
+
+
+// If you change this, then make sure to update the linker scripts as well to
+// make sure you don't overwrite code.
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
+
+#define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
+
+#define BOARD_HAS_CRYSTAL 0
+
+#define DEFAULT_I2C_BUS_SCL (&pin_PA08)	/* ANALOG 5 */
+#define DEFAULT_I2C_BUS_SDA (&pin_PA09)	/* ANALOG 6 */
+
+//#define DEFAULT_SPI_BUS_SCK (&pin_PB11)
+//#define DEFAULT_SPI_BUS_MOSI (&pin_PB10)
+//#define DEFAULT_SPI_BUS_MISO (&pin_PA12)
+
+#define DEFAULT_UART_BUS_RX (&pin_PB08)	/* ANALOG 1 */
+#define DEFAULT_UART_BUS_TX (&pin_PB09)	/* ANALOG 2 */
+
+// USB is always used internally so skip the pin objects for it.
+#define IGNORE_PIN_PA24     1
+#define IGNORE_PIN_PA25     1

ports/atmel-samd/boards/snekboard/mpconfigboard.mk

@@ -0,0 +1,16 @@
+LD_FILE = boards/samd21x18-bootloader-external-flash.ld
+USB_VID = 0x239A
+USB_PID = 0x8023
+USB_PRODUCT = "SnekBoard"
+USB_MANUFACTURER = "keithp.com"
+
+CHIP_VARIANT = SAMD21G18A
+CHIP_FAMILY = samd21
+
+SPI_FLASH_FILESYSTEM = 1
+EXTERNAL_FLASH_DEVICE_COUNT = 1
+EXTERNAL_FLASH_DEVICES = "W25Q16JV_IQ"
+LONGINT_IMPL = MPZ
+
+CFLAGS_INLINE_LIMIT = 60
+SUPEROPT_GC = 0

ports/atmel-samd/boards/snekboard/pins.c

@@ -0,0 +1,25 @@
+#include "shared-bindings/board/__init__.h"
+
+STATIC const mp_rom_map_elem_t board_global_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_A1), MP_ROM_PTR(&pin_PB08) },
+    { MP_ROM_QSTR(MP_QSTR_A2), MP_ROM_PTR(&pin_PB09) },
+    { MP_ROM_QSTR(MP_QSTR_A3), MP_ROM_PTR(&pin_PA06) },
+    { MP_ROM_QSTR(MP_QSTR_A4), MP_ROM_PTR(&pin_PA07) },
+    { MP_ROM_QSTR(MP_QSTR_A5), MP_ROM_PTR(&pin_PA08) },
+    { MP_ROM_QSTR(MP_QSTR_A6), MP_ROM_PTR(&pin_PA09) },
+    { MP_ROM_QSTR(MP_QSTR_A7), MP_ROM_PTR(&pin_PA10) },
+    { MP_ROM_QSTR(MP_QSTR_A8), MP_ROM_PTR(&pin_PA11) },
+    { MP_ROM_QSTR(MP_QSTR_POWER1), MP_ROM_PTR(&pin_PA12) },
+    { MP_ROM_QSTR(MP_QSTR_DIR1), MP_ROM_PTR(&pin_PA16) },
+    { MP_ROM_QSTR(MP_QSTR_POWER2), MP_ROM_PTR(&pin_PA13) },
+    { MP_ROM_QSTR(MP_QSTR_DIR2), MP_ROM_PTR(&pin_PA17) },
+    { MP_ROM_QSTR(MP_QSTR_POWER3), MP_ROM_PTR(&pin_PA18) },
+    { MP_ROM_QSTR(MP_QSTR_DIR3), MP_ROM_PTR(&pin_PA20) },
+    { MP_ROM_QSTR(MP_QSTR_POWER4), MP_ROM_PTR(&pin_PA19) },
+    { MP_ROM_QSTR(MP_QSTR_DIR4), MP_ROM_PTR(&pin_PA21) },
+    { MP_ROM_QSTR(MP_QSTR_NEOPIXEL), MP_ROM_PTR(&pin_PB11) },
+    { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&board_i2c_obj) },
+    { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&board_spi_obj) },
+    { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&board_uart_obj) },
+};
+MP_DEFINE_CONST_DICT(board_module_globals, board_global_dict_table);