Marketing docs differ from product spec re nRF52810 count of RTC's: RTC2 is absent?

[butch]

The Nordic nRF52810 Product Brochure and a module manufacturer Raytac's documents say the nRF52810 has three RTC's.

This post by a Nordic employee says the nRF52810 has just two RTC's:   https://devzone.nordicsemi.com/f/nordic-q-a/29071/main-differences-between-52810-and-52832/115283#115283

Also, files in the 14,2 SDK such as device/nrf52810_peripherals.h define RTC_COUNT equal to 2.

Which is correct?

This bit me because I was developing for the nrf52810 on the 52DK, using RTC2, and it seemed to work.  Probably I was not using the correct compiler defines (maybe I was using -DNRF52 instead of -DNRF52810_XXAA and -DDEVELOP_IN_NRF52832.)  When I switched to more correct compiler defines for some but not all of my code, it seemed to compile, but stopped working, with a hardfault.  I would stress that using the newer SDK,  a developer must define a very specific chip such as -DNRF52810_XXAA (and not just -DNR52 or -DNRF52810) and the developer must do so for ALL their code, including libraries that might reference RTC2 or other peripherals that are absent from the 52810.

[Håkon Alseth]

Hi,

 

I recommend using our datasheet as a reference instead of the module vendor specs. Here you can see the amount of RTC instances available for the nRF52810, which is RTC0 and RTC1:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52810.ps/rtc.html?cp=2_2_0_5_15_9#topic

 

What were you using the extra RTC-peripheral as, and is it possible that you can add an extra app_timer handler to sort this out instead?

 

Best regards,

Håkon

[butch]

Yes, I should use the data sheet.  I am just reporting an inconsistency in Nordic docs (the product brochure.)

It is not a problem for me, since I can easily use RTC1 instead of RTC2.

More feedback, in a helpful spirit:

I don't use app_timer because several bugs have been reported, and reading the code makes me nervous about its reliability, because I can't understand it easily while I think it should be a simple algorithm that anyone could understand.  

Nordic should produce a comparison chart of the 52810 and 52832.  Too many people seem to be caught unaware that some peripherals or Softdevice capabilities (no central/observer) are missing.  Speaking for myself, I thought: it just has less memory, no FPU, and a few missing peripherals,  all of which I don't use.   Only to find other subtle differences on the chip and in the toolchain (FPU ABI soft, and maybe size optimization required.)   Since I buy only a few, the difference in price is not worth the headache in porting and in maintaining another build configuration.

[Håkon Alseth]

You're right. there are differences between the two chips that we should have flagged higher in our documentation. In a project, there's always a "sweet spot" between price vs. development cost, and it is not always that it evens out when going for the chip with the least amount of features in terms of time spent on optimizing to make things fit.

We have a table here, which shows the differences between each device in the nRF52-family:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/development/keydef/PLUGINS_ROOT/com.nordic.infocenter.nrf52/dita/nrf52/nrf52_series.html

 

Cheers,

Håkon

 

 

[butch]

For other readers, also note the nRF52810 :

- only supports s112, with reduced capability from s132

- has no instruction cache, so has lower benchmark cpu speed (and might require code changes w/r timing)

- uses less power per instruction

As discussed here: devzone.nordicsemi.com/.../main-differences-between-52810-and-52832