Bluepill STM32F103C8 support for Mbed OS 6
Bluepill board support for Mbed OS 6
Warning
It does not work with the Mbed Online Compiler.
This is an example of configuration for the Bluepill board for Mbed OS 6.
It shows how to create a custom board support based on Mbed OS and how to compile a simple Blinky application.
Note this project makes use of the full Mbed OS with RTOS included. It's possible to make changes in the configuration to support the Baremetal profile and reduce memory requirements - see this.
Example application
This repository includes blinky.cpp as an example application to demonstrate how to use the Bluepill custom board support. It's expected to work out of the box using both Mbed CLI and Mbed Studio.
Note this test application can be ignored using the MBED_BLINKY_EXAMPLE macro in mbed_app.json, so you can add your own files and application on top of this project.
You can follow these steps to import and compile with Mbed CLI:
mbed import https://os.mbed.com/users/hudakz/code/mbed-os-bluepill mbed compile -t GCC_ARM -m bluepill
Bluepill and Mbed OS version support
| Bluepill | Mbed OS (hash) | Status |
|---|---|---|
| preview | 6.2.0 (#a2ada74770 ) | Compiles and runs ok |
Updating Mbed OS
Note not every version of Mbed OS is being tested, therefore update at your own risk. Unless strictly required, you should stick to versions of Mbed OS that are known to work ok.
If you do want to udpate Mbed OS, then follow these steps:
cd mbed-os mbed update <mbed-os hash / tag>
Testing
This application has been tested on the Bluepill board and runs ok: it blinks and LED and sends a message over the serial port (115200 bauds - see mbed_app.json).
However, it's recomended to run regression tests based on the Greentea framework whether possible (more details to be added).
Programming with STLink programming utility
The Bluepill board doesn't have a programming interface on board. However, it's easy to connect an external adapter such as the STLink/V2 and get it working in minutes.
Use the STM32 ST-Link utility to program the binary into the device.

Wire the Bluepill to the STLink and serial adapter as follow:
| Bluepill | STLink (20-pin JTAG) | Serial adapter |
|---|---|---|
| SDWIO (CN4) | 7 | - |
| SWCLK (CN4) | 9 | - |
| RESET | 15 | - |
| GND | 4 | GND |
| TX (PA_2) | - | RX |
| RX (PA_3) | - | TX |
ST-LINK/V2 JTAG pintout

This is the pinout of the Bluepill board:

Additional example programs
Bare metal on Bluepill
Bare metal with EventQueue on Bluepill
Warning
The examples above are not meant to be compiled with the online compiler. Follow these steps to import and compile them with Mbed CLI:
mbed import Program's_URL mbed compile -t GCC_ARM -m bluepill
Known issues
- Please check the issues reported.
Diff: TARGET_BLUEPILL/device/system_clock.c
- Revision:
- 0:2577a4fb6e72
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/TARGET_BLUEPILL/device/system_clock.c Wed May 13 12:25:39 2020 +0000
@@ -0,0 +1,232 @@
+/* mbed Microcontroller Library
+* Copyright (c) 2006-2017 ARM Limited
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+/**
+ * This file configures the system clock as follows:
+ *-----------------------------------------------------------------------------
+ * System clock source | 1- PLL_HSE_EXTC | 3- PLL_HSI
+ * | (external 8 MHz clock) | (internal 8 MHz)
+ * | 2- PLL_HSE_XTAL |
+ * | (external 8 MHz xtal) |
+ *-----------------------------------------------------------------------------
+ * SYSCLK(MHz) | 72 | 64
+ *-----------------------------------------------------------------------------
+ * AHBCLK (MHz) | 72 | 64
+ *-----------------------------------------------------------------------------
+ * APB1CLK (MHz) | 36 | 32
+ *-----------------------------------------------------------------------------
+ * APB2CLK (MHz) | 72 | 64
+ *-----------------------------------------------------------------------------
+ * USB capable (48 MHz precise clock) | NO | NO
+ *-----------------------------------------------------------------------------
+ ******************************************************************************
+ */
+
+#include "stm32f1xx.h"
+
+/*!< Uncomment the following line if you need to relocate your vector Table in
+ Internal SRAM. */
+/* #define VECT_TAB_SRAM */
+#define VECT_TAB_OFFSET 0x00000000U /*!< Vector Table base offset field.
+ This value must be a multiple of 0x200. */
+
+
+/* Select the clock sources (other than HSI) to start with (0=OFF, 1=ON) */
+#define USE_PLL_HSE_EXTC (0) /* Use external clock */
+#define USE_PLL_HSE_XTAL (1) /* Use external xtal */
+
+
+#if (USE_PLL_HSE_XTAL != 0) || (USE_PLL_HSE_EXTC != 0)
+uint8_t SetSysClock_PLL_HSE(uint8_t bypass);
+#endif
+
+uint8_t SetSysClock_PLL_HSI(void);
+
+
+/**
+ * @brief Setup the microcontroller system
+ * Initialize the Embedded Flash Interface, the PLL and update the
+ * SystemCoreClock variable.
+ * @note This function should be used only after reset.
+ * @param None
+ * @retval None
+ */
+void SystemInit (void)
+{
+ /* Reset the RCC clock configuration to the default reset state(for debug purpose) */
+ /* Set HSION bit */
+ RCC->CR |= 0x00000001U;
+
+ /* Reset SW, HPRE, PPRE1, PPRE2, ADCPRE and MCO bits */
+#if !defined(STM32F105xC) && !defined(STM32F107xC)
+ RCC->CFGR &= 0xF8FF0000U;
+#else
+ RCC->CFGR &= 0xF0FF0000U;
+#endif /* STM32F105xC */
+
+ /* Reset HSEON, CSSON and PLLON bits */
+ RCC->CR &= 0xFEF6FFFFU;
+
+ /* Reset HSEBYP bit */
+ RCC->CR &= 0xFFFBFFFFU;
+
+ /* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRE/OTGFSPRE bits */
+ RCC->CFGR &= 0xFF80FFFFU;
+
+#if defined(STM32F105xC) || defined(STM32F107xC)
+ /* Reset PLL2ON and PLL3ON bits */
+ RCC->CR &= 0xEBFFFFFFU;
+
+ /* Disable all interrupts and clear pending bits */
+ RCC->CIR = 0x00FF0000U;
+
+ /* Reset CFGR2 register */
+ RCC->CFGR2 = 0x00000000U;
+#elif defined(STM32F100xB) || defined(STM32F100xE)
+ /* Disable all interrupts and clear pending bits */
+ RCC->CIR = 0x009F0000U;
+
+ /* Reset CFGR2 register */
+ RCC->CFGR2 = 0x00000000U;
+#else
+ /* Disable all interrupts and clear pending bits */
+ RCC->CIR = 0x009F0000U;
+#endif /* STM32F105xC */
+
+#if defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F101xG) || defined(STM32F103xE) || defined(STM32F103xG)
+#ifdef DATA_IN_ExtSRAM
+ SystemInit_ExtMemCtl();
+#endif /* DATA_IN_ExtSRAM */
+#endif
+
+#ifdef VECT_TAB_SRAM
+ SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM. */
+#else
+ SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH. */
+#endif
+
+}
+
+/**
+ * @brief Configures the System clock source, PLL Multiplier and Divider factors,
+ * AHB/APBx prescalers and Flash settings
+ * @note This function should be called only once the RCC clock configuration
+ * is reset to the default reset state (done in SystemInit() function).
+ * @param None
+ * @retval None
+ */
+void SetSysClock(void)
+{
+ /* 1- Try to start with HSE and external clock */
+#if USE_PLL_HSE_EXTC != 0
+ if (SetSysClock_PLL_HSE(1) == 0)
+#endif
+ {
+ /* 2- If fail try to start with HSE and external xtal */
+#if USE_PLL_HSE_XTAL != 0
+ if (SetSysClock_PLL_HSE(0) == 0)
+#endif
+ {
+ /* 3- If fail start with HSI clock */
+ if (SetSysClock_PLL_HSI() == 0) {
+ while(1) {
+ // [TODO] Put something here to tell the user that a problem occured...
+ }
+ }
+ }
+ }
+
+ /* Output clock on MCO1 pin(PA8) for debugging purpose */
+ //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_SYSCLK, RCC_MCODIV_1); // 72 MHz or 64 MHz
+}
+
+#if (USE_PLL_HSE_XTAL != 0) || (USE_PLL_HSE_EXTC != 0)
+/******************************************************************************/
+/* PLL (clocked by HSE) used as System clock source */
+/******************************************************************************/
+uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
+{
+ RCC_ClkInitTypeDef RCC_ClkInitStruct;
+ RCC_OscInitTypeDef RCC_OscInitStruct;
+
+ /* Enable HSE oscillator and activate PLL with HSE as source */
+ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
+ if (bypass == 0) {
+ RCC_OscInitStruct.HSEState = RCC_HSE_ON; /* External 8 MHz xtal on OSC_IN/OSC_OUT */
+ } else {
+ RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS; /* External 8 MHz clock on OSC_IN */
+ }
+ RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
+ RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+ RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
+ RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9; // 72 MHz (8 MHz * 9)
+ if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+ return 0; // FAIL
+ }
+
+ /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
+ RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
+ RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK; // 72 MHz
+ RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1; // 72 MHz
+ RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2; // 36 MHz
+ RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1; // 72 MHz
+ if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) {
+ return 0; // FAIL
+ }
+
+ /* Output clock on MCO1 pin(PA8) for debugging purpose */
+ //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSE, RCC_MCODIV_1); // 8 MHz
+
+ return 1; // OK
+}
+#endif
+
+/******************************************************************************/
+/* PLL (clocked by HSI) used as System clock source */
+/******************************************************************************/
+uint8_t SetSysClock_PLL_HSI(void)
+{
+ RCC_ClkInitTypeDef RCC_ClkInitStruct;
+ RCC_OscInitTypeDef RCC_OscInitStruct;
+
+ /* Enable HSI oscillator and activate PLL with HSI as source */
+ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_HSE;
+ RCC_OscInitStruct.HSIState = RCC_HSI_ON;
+ RCC_OscInitStruct.HSEState = RCC_HSE_OFF;
+ RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
+ RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+ RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI_DIV2;
+ RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16; // 64 MHz (8 MHz/2 * 16)
+ if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+ return 0; // FAIL
+ }
+
+ /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
+ RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
+ RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK; // 64 MHz
+ RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1; // 64 MHz
+ RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2; // 32 MHz
+ RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1; // 64 MHz
+ if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) {
+ return 0; // FAIL
+ }
+
+ /* Output clock on MCO1 pin(PA8) for debugging purpose */
+ //HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_1); // 8 MHz
+
+ return 1; // OK
+}
+