SPI failure in case of modifications to unrelared code segment

[Jawad]

Hi everyone,

I am using nrf52832 with SDK version 11.0 for an IoT application. I am communicating with Atmel ATWINC 1500 module through SPI in order to connect to Wifi. My code was working fine until I added few new lines of code unrelated to SPI. Now when I run the project on Nordic hardware I get following SPI read errors.

(APP)(ERR)[spi_data_read][385][nmi spi]: Failed data response read...(00) (APP)(ERR)[spi_read_reg][625][nmi spi]: Failed data read...

I know that this error occurs when there is some issue with pin assignment for SPI interface but I have verified all the pin assignments. The stranger thing is that the project starts working fine if I comment out any part of the project totally unrelated with SPI. Following are the results when I compile the project using Eclipse.

'C:/Program Files (x86)/GNU Tools ARM Embedded/5.4 2016q3/bin/arm-none-eabi-size' _build/nrf52832_xxaa.out text data bss dec hex filename 56312 1436 37904 95652 175a4 _build/nrf52832_xxaa.out

It might be a memory issue or some other issue. I have tried debugging it but failed so any leads or suggestion about where the problem might be or how to debug such an issue will be highly appreciated. My Make file and start up file is attached.

arm_startup_nrf52.s Makefile

[Jawad]

13kB seems to be the upper limit as I start getting "region RAM overflowed with stack" from 14kB

[bjorn-spockeli]

Are you using the heap in your project? If not then you can set the heap size to zero by adding the following assembler flag.

ASMFLAGS += -D__HEAP_SIZE=0

If __HEAP_SIZEis not defined, then it will be by default set to 8192, i.e. 8kB. You should be able to increase the stack size by setting the heap size to zero.

[Jawad]

Hi Bjorn, Heap size was set to 8192 in the arm startup file and changing it to 0 has solved the problem for now. I can run whole functionality of my project with 8kB stack and heap as 0. Thanks for the support throughout :)

[bjorn-spockeli]

Happy to help :)

[Jawad]

Hi Bjorn,

Setting the heap to 0 solved the problem but now when I enable TLS for mqtt communication I again get region RAM overflowed with stack. I have tried changing stack to 16kB with heap as 0 and also tried with various other combinations of stack and heap but the error stays the same. I think this is a separate issue therefore I posted it here. I am not using any soft device so is there any way of making TLS work by utilizing maximum available RAM?