Hi Oleg, STM32F746 and STM32F769, although both being from the STM32F7 family, they provide different amounts of internal SRAM. The memory map screenshot you posted is from STM32F769. The screenshot below was taken from the STM32F746 datasheet. As you can see, the STM32F746 parts only provide 256KB of SRAM.
[image: image.png] https://www.st.com/en/microcontrollers-microprocessors/stm32f746ng.html Best regards, Gustavo. On Tue, Aug 4, 2020 at 5:04 PM Oleg Evseev <ev.m...@gmail.com> wrote: > Hi David, > > As I see they are used to define: > CONFIG_RAM_END (CONFIG_RAM_START+CONFIG_RAM_SIZE) > which in turn is used in heap allocation (up_allocateheap). > > By the way I am working with px4 master and custom board stm32f767 > (software very close and based on fmu-v5). > And I used > CONFIG_RAM_SIZE=376832 > CONFIG_RAM_START=0x20020000 > but on reboots start to get random hardfaults (looking on address in log > points to heap allocation functions) and sometimes fails advertising uorb > topics (also heap allocation problem as I see). > > While I'm investigating this I notice this difference with RAM size config > and ask this question (of course it may not be related to my issue). > > > вт, 4 авг. 2020 г. в 22:49, David Sidrane <david.sidr...@nscdg.com>: > >> Both are not used in the source. I would assume it is a legacy C&P from >> the F4, that should be removed. >> >> >> >> *From:* Oleg Evseev [mailto:ev.m...@gmail.com] >> *Sent:* Tuesday, August 04, 2020 12:45 PM >> *To:* dev@nuttx.apache.org >> *Subject:* Re: stm32f7 CONFIG_RAM understanding >> >> >> >> No, internal memory. >> >> >> >> For all boards >> >> stm32f769i-disco\ >> stm32f746-ws\ >> stm32f746g-disco\ >> nucleo-144\ >> >> >> >> but just found that except stm32f769i-disco, it understandably defines >> params for SRAM1 368Kb according to MCU memory map >> >> CONFIG_RAM_SIZE=376832 >> CONFIG_RAM_START=0x20020000 >> >> >> >> вт, 4 авг. 2020 г. в 22:27, Gregory Nutt <spudan...@gmail.com>: >> >> External SRAM? >> >> >> >> On 8/4/2020 1:08 PM, Oleg Evseev wrote: >> >> Hi, >> >> >> >> I wonder why stm32f7 boards has such RAM parameters in defconfigs: >> >> CONFIG_RAM_SIZE=245760 >> CONFIG_RAM_START=0x20010000 >> >> >> >> Where do these numbers come from while memory map is this? >> >> [image: изображение.png] >> >> >> >> --- >> >> With regards, >> >> Oleg >> >> >> >> -- Gustavo Henrique Nihei
