nuttx实战项目2：蓝牙有线通信板之一，nsh串口调试

NuttX STM32F205 调试笔记

经过各种调试，整理如下：

程序最开始跑飞
- 出现 hard fault 异常。
- 怀疑是 Bootloader 干扰，通过在 .config 中关闭 Bootloader 才能正确进入执行顺序。
UART1 宏定义问题
- 最开始 board 中 UART1 宏设置不正确。
- 通过删除不必要的设置，并增加调试配置，在 GDB 中观察到可以输出，但程序一直等待接收。
- 强行退出后，NSH 线程挂掉。
串口波特率问题
- 通过示波器测得串口最小单位为 18.4 μs。
- 将串口设置成 56000 波特后可以正常通信。
- 怀疑晶振频率未正确配置，最终修改如下：

diff 复制代码

kelland@HP-Desktop-PC:~/nuttx_new_stm32f205/nuttx$ git diff .
diff --git a/boards/arm/stm32/photon/include/board.h b/boards/arm/stm32/photon/include/board.h
index 3adecc20f6..3401890eca 100644
--- a/boards/arm/stm32/photon/include/board.h
+++ b/boards/arm/stm32/photon/include/board.h
@@ -66,11 +66,11 @@
 
 /* HSI - 16 MHz RC factory-trimmed
  * LSI - 32 KHz RC
- * HSE - On-board crystal frequency is 26MHz
+ * HSE - On-board crystal frequency is 12MHz
  * LSE - 32.768 kHz
  */
 
-#define STM32_BOARD_XTAL        26000000ul
+#define STM32_BOARD_XTAL        12000000ul
 #define STM32_HSI_FREQUENCY     16000000ul
 #define STM32_LSI_FREQUENCY     32000
@@ -90,7 +90,7 @@
  *         = 48,000,000
  */
 
-#define STM32_PLLCFG_PLLM       RCC_PLLCFG_PLLM(26)
+#define STM32_PLLCFG_PLLM       RCC_PLLCFG_PLLM(12)
 #define STM32_PLLCFG_PLLN       RCC_PLLCFG_PLLN(240)
 #define STM32_PLLCFG_PLLP       RCC_PLLCFG_PLLP_2
 #define STM32_PLLCFG_PLLQ       RCC_PLLCFG_PLLQ(5)
@@ -228,6 +228,13 @@
 #  define GPIO_USART1_TX GPIO_USART1_TX_1
 #endif
 
+/* UART2 */
+
+#ifdef CONFIG_STM32_USART2
+#  define GPIO_USART2_RX GPIO_USART2_RX_1 /* PA3 */
+#  define GPIO_USART2_TX GPIO_USART2_TX_1 /* PA2 */
+#endif
+
 /* SPI1 */
 
 #define GPIO_SPI1_MISO   GPIO_SPI1_MISO_1  /* PA6 */
diff --git a/boards/arm/stm32/photon/scripts/photon_jtag.ld b/boards/arm/stm32/photon/scripts/photon_jtag.ld
index 67d7346c05..f1d93d5d3a 100644
--- a/boards/arm/stm32/photon/scripts/photon_jtag.ld
+++ b/boards/arm/stm32/photon/scripts/photon_jtag.ld
@@ -32,7 +32,7 @@
 MEMORY
 {
   flash (rx) : ORIGIN = 0x08000000, LENGTH = 1024K
-  sram (rwx) : ORIGIN = 0x20000000, LENGTH = 112K
+  sram (rwx) : ORIGIN = 0x20000000, LENGTH = 128K
 }
 
 OUTPUT_ARCH(arm)

.config 修改
- 关闭 DFU Bootloader
- 启用 USART2 串口和控制台
kelland@HP-Desktop-PC:~/nuttx_new_stm32f205/nuttx$ diff boards/arm/stm32/photon/configs/nsh/defconfig defconfig
31d30
< CONFIG_PHOTON_DFU_BOOTLOADER=y
45a45

CONFIG_STM32_USART2=y
47c47
< CONFIG_USART1_SERIAL_CONSOLE=y

CONFIG_USART2_SERIAL_CONSOLE=y