Reserved RAM

RE: Reserved RAM

skulkarni — Thu, 05 Dec 2019 04:42:47 GMT

Yes I mean RAM start = 0x200057B8.

Thank you Edvin. I will close this issue now.

RE: Reserved RAM

Edvin — Wed, 04 Dec 2019 12:34:00 GMT

did you mean RAM start = 0x200057B8?

I suggest that you start with some RAM settings that work. Then monitor the log. In the later SDKs, it will say in the log whether you should adjust the RAM settings according to the number of Services and characteristics that you have. The log will let you know if you can adjust the RAM for optimal settings.

BR,

Edvin

RE: Reserved RAM

skulkarni — Wed, 04 Dec 2019 12:30:05 GMT

Hello Edvin,

I looked into this example code ble_app_hrs_pca10040_s132(without FreeRTOS). Here the reserved RAM size is only 10.8KB. Accordingly I adjusted the RAM start location for my project after this reserved RAM size reduced to 10KB.

My firmware works without any issues.

Note: My firmware uses 5 services.

Original RAM start = 0x57B8

I modified it to 0x2800.

Please let me know your suggestion.

RE: Reserved RAM

Edvin — Tue, 03 Dec 2019 16:35:46 GMT

I forgot to mention, but if you want a smaller softdevice, with a bit less features, you can look into using the S112 softdevice. In SDK16.0.0 there are examples for the nrf52832 using s112. Look at SDK16.0.0\examples\ble_peripheral\ble_app_uart\pca10040\s112.

BR,
Edvin

RE: Reserved RAM

Edvin — Tue, 03 Dec 2019 16:30:37 GMT

where is this screenshot from?

I built the project, and it looks like this in SES:

That is the ble_app_hrs_freertos example.

If your app uses more flash than that, then it is probably because something you do in your application requires a lot of ram.

However, the "Reserved RAM" is the RAM reserved for the softdevice.

On the nRF52832, the RAM is mapped from 0x2000 0000 to 0x2001 0000. If you look in the RAM settings of the ble_app_hrs_freertos you will see that it looks like this:

RAM_START=0x200057b8
RAM_SIZE=0xa848

So the RAM from 0x2000 0000 to 0x2000 57b8 is reserved for the softdevice.

0x57b8 = 21.92kB. This is the RAM that the softdevice needs, based on the number of supported connections, the number of services and characteristics.

In SDK12.3.0 the RAM settings of the same example is starting at 0x2000 2128, which is about 8kB. So yes, the later softdevices use more ram, but it is probably because they are more complex, and support more features.

Best regards,

Edvin

RE: Reserved RAM

skulkarni — Tue, 03 Dec 2019 04:15:09 GMT

Hi Edvin,

Please find below. I have started with taking this example code ble_app_hrs_freertos_pca10040_s132.

RE: Reserved RAM

Edvin — Mon, 02 Dec 2019 16:08:30 GMT

Hello,

Where do you read this number from? What example?`Or is it from the softdevice specification?

BR,

Edvin