BC66 OpenCPU RAM retention during deep sleep

nestorayuso · February 13, 2020, 3:32pm

Hi,

I am using BC66 FW version BC66NBR01A10 and OpenCPU version BC66_OpenCPU_NB1_SDK_V1.5_S02

Reading docs I think there is not RAM retention during deep sleep. With small example code I confirm RAM content is lost on deep sleep.

SDK provides Ql_SecureData_Store and Ql_SecureData_Read functions to store vital data I don’t want to lose during deep sleep.

Quectel_BC66-OpenCPU_User_Guide_V1.0.pdf says Ql_SecureData_Store saves two blocks of 50bytes each (on RTC RAM I think).

ql_system.h says Ql_SecureData_Store saves two blocks of 2Kbytes each (on Flash).

which one is correct?
If I only can store data in Flash, this solution is not suitable because I will write in Flash every time I enter deep sleep, which is not good for life cycle of flash.

WizIO · February 13, 2020, 3:41pm

Have SRAM… last page is free
For small data … byte [255]

github.com

Wiz-IO/framework-quectel/blob/master/libraries/cpp_bc66.ld#L5


MEMORY
{
	ROM (rx) :  ORIGIN = 0x08292040, LENGTH = 0x00032000
	RAM (rwx) : ORIGIN = 0x001E7000, LENGTH = 0x00019000	
	RETSRAM (rwx) : ORIGIN = 0x4301F00, LENGTH = 256
}


SECTIONS
{
    . = 0x08292040;
	.initdata :
	{ 
	. = ALIGN(4);
		KEEP(*(.initdata));
	}AT > ROM

nestorayuso · February 14, 2020, 11:40am

Any official statement about that?