Posted on June 05, 2018 at 09:57 Hi
shivananda.halladama
,
Please do not worry, you are not sound naïve.
Let me answer to your questions (I will number them for easier tracking later).
1. In case of lost of power supply content of RAM is unpredicted and it should be written there again. In case of your code, you should prepare a procedure in your FLASH memory (which will be executed on each repowering the device) which would copy necessary part of the code to SRAM.
2. ok, but please be careful on PA13, PA14 as those pins are used by
#swd
debugger. The best is to configure them as SWD ones (in
#stm32cubemx
you can select this option within SYS peripheral) to be sure that your debugger will be able to connect to MCU. In case you forget it, you can still start your debug session, but the debugger should be connected in 'connect under reset' mode and it should have connected its reset line to NRST pin of the MCU to control reset of the MCU.
3. clock gating is simply disconnecting the clock to given peripheral on the bus (APB, AHB). By default after the reset most of the peripherals (except FLASH, SRAM, NVIC) have the clock gated and you need to connect it before you perform any write to peripheral registers. To connect bus clock to peripherals you are using function (macro) __HAL_RCC_GPIOC_CLK_ENABLE() : to disconnect you are using functions (macros): __HAL_RCC_GPIOC_CLK_DISABLE();. More information you can find in Reset and Clock Configuration section within reference manual (or RCC section in the library)
4. By default after the reset each STM32 is clocked by one of internal RC oscillators without PLL. It is not more than 16MHz, so usually we need higher frequencies, thus we are enabling PLLs, selecting external crystal as a clock source. Higher frequency on the core, buses mean higher current consumption. In your application you should analyze which frequency is optimum for each of peripheral you are using and configure all the prescalers to have those values. You can use for this purpose STM32CubeMX application, there in Clock Configuration tab you can see all the relations among clocking system in you STM
You can refer to PWR section in
#stm32f0%20cube
library. For
#stm32f091rc
based
#nucleo-f0
board you can find example within the path:
.\STM32Cube_FW_F0_V1.9.0\Projects\STM32F091RC-Nucleo\Examples\PWR\PWR_CurrentConsumption\
5.ok
6. DMA is used to copy some data from peripherals to memory in regular time slots without intervention of CPU. You can find a lot of examples within HAL library of your MCU. In example for STM32F091RC family those can be found within the paths (some examples, as there are much more on most of the peripherals):
.\STM32Cube_FW_F0_V1.9.0\Projects\STM32F091RC-Nucleo\Examples\DMA\DMA_FLASHToRAM\
.\STM32Cube_FW_F0_V1.9.0\Projects\STM32F091RC-Nucleo\Examples\ADC\ADC_Sequencer\
Best Regards,
Artur
