Add new board: Nucleo-F042K6

Signed-off-by: Riku Viitanen <riku.viitanen@protonmail.com>

boards/nucleo-f042k6.h

@@ -0,0 +1,37 @@
+#ifndef __BOARD_H__
+#define __BOARD_H__
+
+#include <stdbool.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+
+/*
+ * Board definitions for ST's Nucleo-32 reference board with STM32F042K6
+ *      https://www.st.com/en/evaluation-tools/nucleo-f042k6.html
+ *
+ * The USB port on the board is connected to an onboard ST-LINK.
+ * F042's actual USB port is exposed on the pin headers:
+ * 
+ *  USB | Nucleo-F042
+ * -----|--------------
+ *  D-  | CN3-13 (D10)
+ *  D+  | CN3-5 (D2)
+ *  5V  | CN4-4, (5V)
+ *  GND | CN4-2, (GND)
+ *
+ */
+
+#define BOARD_USE_DEBUG_PINS_AS_GPIO false
+
+#define BOARD_RCC_LED                RCC_GPIOB
+#define BOARD_PORT_LED               GPIOB
+#define BOARD_PIN_LED                GPIO3
+
+/* Only LED, high active, use as idle. */
+#define BOARD_LED_HIGH_IS_BUSY       false
+
+/* STM32F0x2 has internal USB pullup. */
+
+/* Currently you can only use SPI1, since it has highest clock. */
+
+#endif /* __BOARD_H__ */

boards/nucleo-f042k6.mk

@@ -0,0 +1,4 @@
+ARCH_FLAGS = -DSTM32F0 -mthumb -mcpu=cortex-m0 -msoft-float
+LDSCRIPT   = boards/ld/stm32f04xz6.ld
+LIBOPENCM3 = libopencm3/lib/libopencm3_stm32f0.a
+OPENCM3_MK = lib/stm32/f0