RAM retention problem

RE: RAM retention problem

strengthstrong — Fri, 09 Nov 2018 09:33:10 GMT

#define __retention __attribute__((section("retention_mem_area0"), zero_init)) // essential

What do you need to add?

RE: RAM retention problem

rakesh_hirur — Tue, 24 Jul 2018 04:50:52 GMT

what about the size of the ".retained section" in placement file ? It is specified as "8" in "ram_retention_softreset_clean". Is it 8 bytes or 8 RAM sections?

RE: RAM retention problem

tesc — Tue, 17 Jul 2018 18:20:20 GMT

That would be the case, yes.

RE: RAM retention problem

enkavak — Mon, 09 Jul 2018 08:35:40 GMT

For every variable do I need to define it like below for ram retention ?

uint32_t ram_value __attribute__((section(".retained_section"))) = 0;

RE: RAM retention problem

Håkon Alseth — Thu, 05 Jul 2018 08:41:05 GMT

Here's an example on how to retain a variable or section with systemoff/soft-reset for SES: devzone.nordicsemi.com/.../ram_5F00_retention_5F00_softreset_5F00_clean.zip

To integrate this into your own project, please note the added section ".retained_section" in the flash_placement.xml file, as this must be added into your project.

Best regards,

Håkon

RE: RAM retention problem

enkavak — Thu, 05 Jul 2018 06:35:14 GMT

A1) I'm using Systemoff

A2) Segger Embedded studio

RE: RAM retention problem

Håkon Alseth — Thu, 05 Jul 2018 06:32:40 GMT

Hi,

In WFE (or sd_app_evt_wait when using the softdevice) there is no need to change the RAM retention settings (assuming using reset values), as WFE will start executing based on where it previously was (just like any C function).

However, if using SystemOFF, then a wakeup will generate a reset condition, thus must of your states are reset. When using SystemOFF, it is not enough just to set the RAM retention in sleep, but you will also need to make sure that your firmware does not clear/overwrite your data at boot up. This is normally done by making a no-init/zero_init section.

Q1. Are you using Systemoff?

Q2: What compiler are you using?

Kind regards,

Håkon