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Frederic Pillon edited this page Mar 6, 2023 · 10 revisions

Custom definitions

Several definitions can be redefined by the end user by different ways:

Quick links

Change interrupt priority values

Default IRQ priorities are defined in the core which can be re-defined using below definitions:

  • UART_IRQ_PRIO
  • EXTI_IRQ_PRIO
  • I2C_IRQ_PRIO
  • RTC_IRQ_PRIO
  • TIM_IRQ_PRIO
  • USBD_IRQ_PRIO

Same for IRQ sub-priorities:

  • UART_IRQ_SUBPRIO
  • EXTI_IRQ_SUBPRIO
  • I2C_IRQ_SUBPRIO
  • RTC_IRQ_SUBPRIO
  • TIM_IRQ_SUBPRIO
  • USBD_IRQ_SUBPRIO

Example:

Using build_opt.h:

-DUSBD_IRQ_PRIO=2 -DUSBD_IRQ_SUBPRIO=2

Custom startup file

Core use a default startup file included thanks CMSIS_STARTUP_FILE definition:

../blob/main/cores/arduino/stm32/startup_stm32yyxx.S

which is defined thanks:

../blob/main/cores/arduino/stm32/stm32_def_build.h

and provided thanks the CMSIS Device from ST (in STM32YYxx/Source/Templates/gcc/):

../blob/main/system/Drivers/CMSIS/Device/ST

It is possible to redefine the CMSIS_STARTUP_FILE or define a custom startup file in the variant.

Redefine the default startup file

Using build_opt.h:

-DCMSIS_STARTUP_FILE=\"mystartup_file.s\"

Then add your mystartup_file.s in the sketch folder (i.e. in a tab of your sketch files).

Example for Nucleo_L476RG:

-DCMSIS_STARTUP_FILE=\"startup_stm32l476xx.s\

Custom startup file in the variant

It required to define CUSTOM_STARTUP_FILE in the boards.txt and add a *.S file in the variant/ folder.

Syntax in the board.txt: xxx.build.startup_file=-DCUSTOM_STARTUP_FILE

Example for Nucleo_L476RG:

Nucleo_64.menu.pnum.NUCLEO_L476RG.build.startup_file=-DCUSTOM_STARTUP_FILE

Then add a *.S file in the variant/NUCLEO_L476RG/ folder.

Important note: file extension must be .S not .s

Custom PinMap array

Each variant provides a PeripheralPins.c including all PinMap arrays per STM32 peripherals: ADC, I2C, SPI, TIM, U(S)ART, USB,...

A pin can be used with several peripheral instances anyway for a dedicated project not all possibilities are required. All those possibilities used FLASH so to save some space, those arrays can be overridden at sketch level as they are defined as WEAK.

Example for the ADC PinMap of the NUCLEO_F103RB:

#ifdef HAL_ADC_MODULE_ENABLED
WEAK const PinMap PinMap_ADC[] = {
  {PA_0,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 0, 0)}, // ADC1_IN0
  {PA_0_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 0, 0)}, // ADC2_IN0
  {PA_1,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 1, 0)}, // ADC1_IN1
  {PA_1_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 1, 0)}, // ADC2_IN1
  {PA_2,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 2, 0)}, // ADC1_IN2
  {PA_2_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 2, 0)}, // ADC2_IN2
  {PA_3,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 3, 0)}, // ADC1_IN3
  {PA_3_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 3, 0)}, // ADC2_IN3
  {PA_4,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 4, 0)}, // ADC1_IN4
  {PA_4_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 4, 0)}, // ADC2_IN4
  {PA_5,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 5, 0)}, // ADC1_IN5
  {PA_5_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 5, 0)}, // ADC2_IN5
  {PA_6,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 6, 0)}, // ADC1_IN6
  {PA_6_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 6, 0)}, // ADC2_IN6
  {PA_7,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 7, 0)}, // ADC1_IN7
  {PA_7_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 7, 0)}, // ADC2_IN7
  {PB_0,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 8, 0)}, // ADC1_IN8
  {PB_0_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 8, 0)}, // ADC2_IN8
  {PB_1,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 9, 0)}, // ADC1_IN9
  {PB_1_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 9, 0)}, // ADC2_IN9
  {PC_0,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 10, 0)}, // ADC1_IN10
  {PC_0_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 10, 0)}, // ADC2_IN10
  {PC_1,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 11, 0)}, // ADC1_IN11
  {PC_1_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 11, 0)}, // ADC2_IN11
  {PC_2,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 12, 0)}, // ADC1_IN12
  {PC_2_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 12, 0)}, // ADC2_IN12
  {PC_3,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 13, 0)}, // ADC1_IN13
  {PC_3_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 13, 0)}, // ADC2_IN13
  {PC_4,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 14, 0)}, // ADC1_IN14
  {PC_4_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 14, 0)}, // ADC2_IN14
  {PC_5,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 15, 0)}, // ADC1_IN15
  {PC_5_ALT1, ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 15, 0)}, // ADC2_IN15
  {NC,        NP,   0}
};
#endif

Project will uses only PA_0 and PA_1 for ADC. Moreover user wants PA_0 use ADC2.

So, it can be redefined at sketch level to define only those pins (-360 bytes):

const PinMap PinMap_ADC[] = {
  {PA_0,      ADC2, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 0, 0)}, // ADC2_IN0
  {PA_1,      ADC1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 1, 0)}, // ADC1_IN1
  {NC,    NP,    0}
};

I2C Timing

Some STM32 series require to compute I2C timing value for the TIMINGR register depending of the specific I2C clock source configuration to ensure correct I2C speed.

As this calculation of all timing values can consume huge time. By default, only the first 8 valid timing will be computed:

#ifndef I2C_VALID_TIMING_NBR
#define I2C_VALID_TIMING_NBR          8U
#endif

It can be redefined thanks the variant.h or build_opt.h or hal_conf_extra.h

Example to compute 64 valid timing value

  • Using build_opt.h:
-DI2C_VALID_TIMING_NBR=64
  • Using variant.h or hal_conf_extra.h:
#define I2C_VALID_TIMING_NBR 64

Higher number ensure lowest clock error but require more time to compute depending of the board.

Moreover, to avoid time spent to compute the I2C timing, it can be defined in the variant.h or build_opt.h or hal_conf_extra.h with:

  • I2C_TIMING_SM for Standard Mode (100kHz)
  • I2C_TIMING_FM for Fast Mode (400kHz)
  • I2C_TIMING_FMP for Fast Mode Plus (1000kHz)

Example for a STM32F0xx using HSI clock as I2C clock source, in variant.h:

#define I2C_TIMING_SM           0x00201D2B
#define I2C_TIMING_FM           0x0010020A

I2C timeout in tick unit

Since core version higher than 1.9.0.

I2C timeout in tick unit can be redefined. Default: 100

#ifndef I2C_TIMEOUT_TICK
#define I2C_TIMEOUT_TICK        100
#endif

It can be redefined thanks the variant.h or build_opt.h or hal_conf_extra.h

Example to decrease or increase I2C timeout in tick unit value

  • Using build_opt.h:
-DI2C_VALID_TIMING_NBR=50
  • Using variant.h or hal_conf_extra.h:
#define I2C_VALID_TIMING_NBR 120

F_CPU

To avoid any issue with F_CPU value, it is defined by default to SystemCoreClock value which is updated automatically after each clock configuration update.

Some libraries use F_CPU at build time for conditional purpose (example Arduino_Core_STM32/#612).

F_CPU can be redefined at build time using build_opt.h or hal_conf_extra.h then it will be possible to define it as a constant.

Important note: user have to ensure to set it to the proper value.

Serial Rx/Tx buffer size

By default, Serial Rx/Tx buffer size are defined like this:

#if !defined(SERIAL_TX_BUFFER_SIZE)
#define SERIAL_TX_BUFFER_SIZE 64
#endif
#if !defined(SERIAL_RX_BUFFER_SIZE)
#define SERIAL_RX_BUFFER_SIZE 64
#endif

Each size can be redefined at build time using build_opt.h or hal_conf_extra.h

A "power of 2" buffer size is recommended to dramatically optimize all the modulo operations for ring buffers.

Example using build_opt.h:

-DSERIAL_RX_BUFFER_SIZE=256 -DSERIAL_TX_BUFFER_SIZE=256

SystemClock_Config

Each variant define a default system clock configuration anyway user can redefine his own system clock configuration at sketch level. For example to change the source clock or decrease frequency. It is important to prefix the new function by extern "C" in ino or cpp file:

extern "C" void SystemClock_Config() {
  // new clock config
}

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