High RAM Application Questions

[Dave_couling]

According to the *.map file the .bss (RAM) usage for my Application is 0x16b8 or 5816 bytes. This is obviously a very high RAM Application, likely due to the abundance of app_timers I use. I am using SDK6.1 and SD7.1. I want to make sure I'm not going to run into RAM issues at RUN-TIME. With this RAM spec in the .map file do I need to modify the gcc_startup_nrf51.s ? Or modify any other files to account for this RAM usage? Any other considerations I should be mindful of? Thank you for your advisement Nordic.

-DC

[RK]

Don't totally understand the question. If the app links without error and fits in the available space, it works, the link script has a check for this. The startup file is entirely generic and just copies things from one place to another, it doesn't matter if it copies 1 byte, 10 bytes or 16Kb.

What issues were you concerned about, perhaps I'm just missing the point?

That is a lot of RAM usage, the map file should tell you what it's all used for, although they're annoyingly tricky to read, you might want to confirm to yourself that it is app timer usage (they use that much??) and not something else.

[RK]

That's odd - I can connect to running boards without a power cycle, it connects then I can halt. I'll try one over battery power later and check it's true in that case as well. There are other options for getting debug info later but they require manually erasing a flash page, dumping the registers and the contents of the stack page, you can try that, it's 30-40 lines of assembler. Then you pull the data off and laboriously cull through it.

So you think that it's the scheduler queue filling up. What do you do if app_sched_event_put() returns NRF_ERROR_NO_MEM? Do you use APP_ERR_CHECK() on it and go to the error handler? can you drop events if you can't queue them, can you at least make it light a different LED so you know this is the case?

A quick look at the code for app_timer says it only calls the scheduler on timeout events.