nRF52810 -> nRF52805 firmware compatibility?

RE: nRF52810 -> nRF52805 firmware compatibility?

ovrebekk — Fri, 11 Dec 2020 14:40:36 GMT

Hi Sydney

I have asked around here and there, but so far I haven't found anything.

I will check in with a couple more people to be sure.

One comment I got is that it is critical to ensure that the peripherals you use are located at the same address in the memory map, if you want to use the same code. If this is not the case you would need to run a runtime check that verifies the chip type, and changes the peripheral address based on this.

Best regards
Torbjørn

RE: nRF52810 -> nRF52805 firmware compatibility?

Sydney — Thu, 10 Dec 2020 00:35:00 GMT

Thanks. This is all really helpful. This is probably enough to consider this issue resolved, but I'd be interested if you've received or are expecting any feedback from your team about whether something like this has been tested internally.

RE: nRF52810 -> nRF52805 firmware compatibility?

ovrebekk — Tue, 08 Dec 2020 13:40:18 GMT

[quote user="alamysm"]If I start with nRF52810, is limiting PPI channels to 10 (instead of 20) to accommodate nRF52805 as simple as changing PP_CH_NUM from 20 to 10 in nrf52810_peripherals.h?[/quote]

That should be enough, yes, but I would recommend copying these files and renaming them so you don't have to change the originals. In order for this to work you need to define a new chip code (replacing NRF52805_XXAA or NRF52810_XXAA), and update nrf.h to point to your modified files instead of the originals.

[quote user="alamysm"]Similarly, if I start with nRF52805, is limiting max EasyDMA size to accommodate nRF52810 as simple as changing X_EASYDMA_MAXCNT_SIZE #defines in nrf52805_peripherals.h? Looks like I'd have to reduce TWI/SPI values from 14 to 10.[/quote]

Correct, changing these defines should be sufficient.

If you diff the nrf528xx_peripherals.h files it is quite clear what is different (even if this includes some typo fixes and other non consequential differences).

[quote user="alamysm"]There are no dev boards with real nRF52805 parts, are there?[/quote]

Correct. For both the nRF52805 and the nRF52810 the development kit used is the nRF52DK (nRF52832).

[quote user="alamysm"]So since I can't actually test "nRF52810 code" on real nRF52805 hardware until/unless I build a custom board, it might make more sense to compile for nRF52805 and get it working on my nRF52810 board.[/quote]

At some point you need to test on both platforms anyway, but I agree that it makes sense to base your project around the nRF52805.

As I said earlier I think the safest way is to create new header files that limit the functionality to the lowest common denominator between the two devices.

Best regards
Torbjørn

RE: nRF52810 -> nRF52805 firmware compatibility?

Sydney — Mon, 07 Dec 2020 21:52:16 GMT

If I start with nRF52810, is limiting PPI channels to 10 (instead of 20) to accommodate nRF52805 as simple as changing PP_CH_NUM from 20 to 10 in nrf52810_peripherals.h?

Similarly, if I start with nRF52805, is limiting max EasyDMA size to accommodate nRF52810 as simple as changing X_EASYDMA_MAXCNT_SIZE #defines in nrf52805_peripherals.h? Looks like I'd have to reduce TWI/SPI values from 14 to 10.

There are no dev boards with real nRF52805 parts, are there? Only emulated? So since I can't actually test "nRF52810 code" on real nRF52805 hardware until/unless I build a custom board, it might make more sense to compile for nRF52805 and get it working on my nRF52810 board.

RE: nRF52810 -> nRF52805 firmware compatibility?

ovrebekk — Mon, 07 Dec 2020 14:01:09 GMT

Whichever approach you pick there will be some possible pitfalls, because of missing functionality in one device over the other.

As an example the nRF52805 only has 10 PPI channels, vs 20 in the nRF52810, and lacks the PWM, PDM and COMP interfaces. If you compile for the nRF52810 you would need to make sure that you don't access any of these features.

Best regards
Torbjørn

RE: nRF52810 -> nRF52805 firmware compatibility?

Sydney — Fri, 04 Dec 2020 17:48:53 GMT

Thanks for checking into this.

Assuming this can work (and I'll wait to see if you get any additional feedback from your team), it sounds like the correct approach would be to compile for nRF52810 because the nRF52810's smaller EasyDMA length could work on nRF52805 (just not at peak performance) but the nRF52805's larger EasyDMA length would not work at all on nRF52810.

RE: nRF52810 -> nRF52805 firmware compatibility?

ovrebekk — Fri, 04 Dec 2020 15:44:23 GMT

This should be possible, but I will have to check internally if this is something we have tested.

Mostly the nRF52805 has a subset of the functionality in the nRF52810, but since the nRF52805 was released after the nRF52810 there are some minor differences in the nRF52805's favor, such as longer maximum length for EasyDMA transfers in many of the peripherals (TWIM and SPIM for instance).

I will provide more details next week.

Best regards
Torbjørn