How to designate one ram block exclusively for radio use?

RE: How to designate one ram block exclusively for radio use?

ovrebekk — Mon, 24 Aug 2020 08:48:13 GMT

First off you have to create a segment in your flash_placement.xml file, such as this:

<ProgramSection alignment="4" keep="Yes" load="No" name=".radio_RAM_section" start="0x20006000" size="0x2000" />

This has to be kept somewhere within the MemorySegment named RAM, starting with this line:

<MemorySegment name="RAM" start="$(RAM_PH_START)" size="$(RAM_PH_SIZE)">

Then you can put variables into this section by using the __attribute__ keyword, like this:

uint8_t test_buffer[256] __attribute__((section(".radio_RAM_section")));

You will find the flash_placement.xml file I used myself to test this attached, based on one of the ESB examples in the SDK:

devzone.nordicsemi.com/.../flash_5F00_placement.xml

Best regards
Torbjørn

RE: How to designate one ram block exclusively for radio use?

cpeng — Fri, 21 Aug 2020 14:55:58 GMT

Hi Mr. ovrebekk,

we are using segger. We are troubleshooting a radio reception problem so we want to segregate the RAM for radio even, as you have said, it's probably not necessary.

Some code example would be highly appreciated.

RE: How to designate one ram block exclusively for radio use?

ovrebekk — Fri, 21 Aug 2020 11:50:32 GMT

It is possible to create a dedicated RAM section that covers one of the RAM blocks, so that you can control exactly which variables go into that block of the RAM.

Then if you only put the radio buffers into this section you are guaranteed that there won't be any conflict on the DMA slave.

Please look here for an overview of the RAM blocks in the nRF52833.

It shouldn't really be necessary for the radio, since it doesn't access the bus very often (the radio is a relatively low bandwidth peripheral), but I can try to find an example if you are interested.

Which compiler/IDE are you using?

Best regards
Torbjørn