Unpredictable behaviour of RTC2 on nRF24le1

[EwanX]

I found a problem using the RTC2 on the nRF24le1 which i dont know how to solve it.

I am using the RTC2 on the master to generate a TICK interrupt exactly every 1s. With the formula on page 97, i set the compare register RTC2CMP1:RTC2CMP1 to 7FFE which should generate interrupts exactly every 1s. But the behaviour is in two points different as expected.

1. The RTC2 generates interrupts 3-6 ms earlier, so the interval is like 0,996869s which corresponds to 7F98 and not 7FFE.

2. The interval decreases every second one RTC2 tick (like 7F97, 7F96, 7F95, ...). Is this a bug?

How can i solve this, especially the point 2.? I need a constant interval.

Regards

[ovrebekk]

Hi Ewan

This sounds like a good strategy. Adding an external 32k crystal (and the two load caps) should not be too expensive, and allows you to get both low current consumption and accurate timing.