we think about using an nrf52820 for a multi role solution. I know from the Compatibility Matrix that the S140 is supported and qualified for the nrf52820. What I would like to know is if there is enough RAM availabe on the Chip in order run both roles at the same time.
We plan to manage multiple bondings but as far as I know this only influences the flash. The application for the nrf52820 and the GATTS attribute table for both roles will not be that big. For the central role it is planned to use a Long Range connection while for the peripheral role we will use a normal 1Mbit/s connection to a smartphone.
Is the concept I explained above possible for a combination of nrf52820 and S140? Asume RAM and Flash of the application is almost 0 and the GATT table has about 10 typical characteristics in size.
It would be nice if someone can give me a estimation of the RAM that is needed for a small multi role application.
Thanks in advance.
The minimum RAM requirement for the S140 v7.2.0 is 5.6kB, as mentioned in the release notes:2627.s140_nrf52_7.2.0_release-notes.pdf
As you enable more features, such as support for multiple links, larger MTU, larger attribute table etc this number will increase, but based on your description I don't think it will get larger than 10kB.
For an accurate number I suggest you set up a test project and configure the stack as you want. Once you run the example you will get a warning message in the log console stating how much RAM the SoftDevice requires for your particular configuration.
Thanks for the fast response. Unfortunately , my problem is that I only have a nrf52833 board. Therefore I need a solution to be able to estimate the RAM usage of the nrf52820 on the nrf52833. Is this possible?
Based on your sugestion I created a test project in the Keil IDE and used the value from "Total RW size" in the map-File to get an indication of the RAM usage.Does "total RW size" provide a value that can be used to estimate the RAM usage?
By the way I configured the test project for the nrf52833 in order to be able to test it on the device. Does it make any difference in RAM usage if I configure a project for the nrf52820 or for the nrf52833?
The SoftDevice RAM consumption doesn't change from one chip to another. It will be the same on both the nRF52833 and the nRF52820.
There is no dedicated DK for the nRF52820 device, so you should be able to use the nRF52833 board that you have for development.
In the SDK there will be some projects that support a board called "pca10100e", which means they are intended to emulate the nRF52820 device while running on an nRF52833DK, and if you use one of these projects you can check the RAM consumption, and how much RAM is left over, if you were using a real nRF52820 device.