add nrf52840 blehr support

board/Nordic_NRF52840/BSP/Src/mcu_init.c

@@ -0,0 +1,63 @@
+#include "nrf_delay.h"
+#include "nrf_gpio.h"
+#include "nrf_rtc.h"
+#include "simple_uart.h"
+#include "main.h"
+
+/* for printf */
+
+#pragma import(__use_no_semihosting)
+
+struct __FILE
+{
+    int handle;
+};
+
+FILE __stdout;
+
+void _sys_exit(int x)
+{
+    x = x;
+}
+
+int fputc(int ch, FILE *f)
+{
+    simple_uart_put ((uint8_t) ch);
+    return ch;
+}
+
+void _ttywrch(int ch)
+{
+	ch = ch;
+}
+
+void SysTick_Handler(void)
+{
+    tos_knl_irq_enter();
+    tos_tick_handler ();
+    tos_knl_irq_leave();
+}
+
+/** @brief Function starting the internal LFCLK XTAL oscillator.
+ */
+static void lfclk_config(void)
+{
+    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
+    NRF_CLOCK->EVENTS_LFCLKSTARTED  = 0;
+    NRF_CLOCK->TASKS_LFCLKSTART     = 1;
+
+    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {
+        ;
+    }
+
+    NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
+}
+
+void board_init(void)
+{
+    lfclk_config();
+
+    nrf_gpio_range_cfg_output(LED_START, LED_STOP);
+    simple_uart_config(RTS_PIN_NUMBER, TX_PIN_NUMBER, CTS_PIN_NUMBER, RX_PIN_NUMBER, HWFC);
+}
+