Nothing Special / mbed-STM32F103C8

Modification of Mbed-dev library for LQFP48 package microcontrollers: STM32F103C8 (STM32F103C8T6) and STM32F103CB (STM32F103CBT6) (Bluepill boards, Maple mini etc. )

Fork of mbed-STM32F103C8_org by Nothing Special

Library for STM32F103C8 (Bluepill boards etc.).
Use this instead of mbed library.
This library allows the size of the code in the FLASH up to 128kB. Therefore, code also runs on microcontrollers STM32F103CB (eg. Maple mini).
But in the case of STM32F103C8, check the size of the resulting code would not exceed 64kB.

To compile a program with this library, use NUCLEO-F103RB as the target name. !

Changes:

  • Corrected initialization of the HSE + crystal clock (mbed permanent bug), allowing the use of on-board xtal (8MHz).(1)
  • Additionally, it also set USB clock (48Mhz).(2)
  • Definitions of pins and peripherals adjusted to LQFP48 case.
  • Board led LED1 is now PC_13 (3)
  • USER_BUTTON is now PC_14 (4)

    Now the library is complete rebuilt based on mbed-dev v160 (and not yet fully tested).

notes
(1) - In case 8MHz xtal on board, CPU frequency is 72MHz. Without xtal is 64MHz.
(2) - Using the USB interface is only possible if STM32 is clocking by on-board 8MHz xtal or external clock signal 8MHz on the OSC_IN pin.
(3) - On Bluepill board led operation is reversed, i.e. 0 - led on, 1 - led off.
(4) - Bluepill board has no real user button

Information

After export to SW4STM (AC6):

  • add line #include "mbed_config.h" in files Serial.h and RawSerial.h
  • in project properties change Optimisation Level to Optimise for size (-Os)

platform/mbed_application.c

Committer:
mega64
Date:
2017-04-27
Revision:
148:8b0b02bf146f
Parent:
146:03e976389d16

File content as of revision 148:8b0b02bf146f:

/* mbed Microcontroller Library
 * Copyright (c) 2017-2017 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.
 */

#include <stdlib.h>
#include <stdarg.h>
#include "device.h"
#include "platform/mbed_application.h"

#if MBED_APPLICATION_SUPPORT

static void powerdown_nvic(void);
static void powerdown_scb(uint32_t vtor);
static void start_new_application(void *sp, void *pc);

void mbed_start_application(uintptr_t address)
{
    void *sp;
    void *pc;

    // Interrupts are re-enabled in start_new_application
    __disable_irq();

    SysTick->CTRL = 0x00000000;
    powerdown_nvic();
    powerdown_scb(address);

    sp = *((void**)address + 0);
    pc = *((void**)address + 1);
    start_new_application(sp, pc);
}

static void powerdown_nvic()
{
    int isr_count;
    int i;
    int j;

    isr_count = (SCnSCB->ICTR & SCnSCB_ICTR_INTLINESNUM_Msk) >> SCnSCB_ICTR_INTLINESNUM_Pos;
    for (i = 0; i < isr_count; i++) {
        NVIC->ICER[i] = 0xFFFFFFFF;
        NVIC->ICPR[i] = 0xFFFFFFFF;
        for (j = 0; j < 8; j++) {
            NVIC->IP[i * 8 + j] = 0x00000000;
        }
    }
}

static void powerdown_scb(uint32_t vtor)
{
    int i;

    // SCB->CPUID   - Read only CPU ID register
    SCB->ICSR = SCB_ICSR_PENDSVCLR_Msk | SCB_ICSR_PENDSTCLR_Msk;
    SCB->VTOR = vtor;
    SCB->AIRCR = 0x05FA | 0x0000;
    SCB->SCR = 0x00000000;
    // SCB->CCR     - Implementation defined value
    for (i = 0; i < 12; i++) {
#if defined(__CORTEX_M7)
        SCB->SHPR[i] = 0x00;
#else
        SCB->SHP[i] = 0x00;
#endif
    }
    SCB->SHCSR = 0x00000000;
    SCB->CFSR = 0xFFFFFFFF;
    SCB->HFSR = SCB_HFSR_DEBUGEVT_Msk | SCB_HFSR_FORCED_Msk | SCB_HFSR_VECTTBL_Msk;
    SCB->DFSR = SCB_DFSR_EXTERNAL_Msk | SCB_DFSR_VCATCH_Msk |
                SCB_DFSR_DWTTRAP_Msk | SCB_DFSR_BKPT_Msk | SCB_DFSR_HALTED_Msk;
    // SCB->MMFAR   - Implementation defined value
    // SCB->BFAR    - Implementation defined value
    // SCB->AFSR    - Implementation defined value
    // SCB->PFR     - Read only processor feature register
    // SCB->DFR     - Read only debug feature registers
    // SCB->ADR     - Read only auxiliary feature registers
    // SCB->MMFR    - Read only memory model feature registers
    // SCB->ISAR    - Read only instruction set attribute registers
    // SCB->CPACR   - Implementation defined value
}

#if defined (__CC_ARM)

__asm static void start_new_application(void *sp, void *pc)
{
    MOV R2, #0
    MSR CONTROL, R2         // Switch to main stack
    MOV SP, R0
    MSR PRIMASK, R2         // Enable interrupts
    BX R1
}

#elif defined (__GNUC__) || defined (__ICCARM__)

void start_new_application(void *sp, void *pc)
{
    __asm volatile (
        "mov    r2, #0      \n"
        "msr    control, r2 \n" // Switch to main stack
        "mov    sp, %0      \n"
        "msr    primask, r2 \n" // Enable interrupts
        "bx     %1          \n"
        :
        : "l" (sp), "l" (pc)
        : "r2", "cc", "memory"
    );
}

#else

#error "Unsupported toolchain"

#endif

#endif /* MBED_APPLICATION_SUPPORT */