Global Clock on nRF51822?

RE: Global Clock on nRF51822?

Håkon Alseth — Wed, 17 Jul 2013 08:50:18 GMT

You can use TIMER1 or TIMER2 for this. It's sourced by the 16M, so it should give you a good enough resolution.

One thing I'm a bit concerned about is the real-time requirements that you have. As you are already aware of it seems, the stack will block the main application for a given time based on how often and how much data you are sending.

How often is the gyro-sampling-routine called? I know you sample x samples each ms, but I assume it's not sampling every 10 us for eternity?

RE: Global Clock on nRF51822?

Guest — Tue, 16 Jul 2013 16:43:46 GMT

Hmm, not really, its for an integration of a gyroscope signal. I do 100 samples / millisecond so looking for something on the order of microseconds if possible.

The problem i see is that, if say the app_timer interrupt was pushed back due to a high priority interrupt (like BLE stack) it would cause delayed calls to the timer interrupt handler.

RE: Global Clock on nRF51822?

Bastiaan — Tue, 16 Jul 2013 16:43:46 GMT

Hmm, not really, its for an integration of a gyroscope signal. I do 100 samples / millisecond so looking for something on the order of microseconds if possible.

The problem i see is that, if say the app_timer interrupt was pushed back due to a high priority interrupt (like BLE stack) it would cause delayed calls to the timer interrupt handler.

RE: Global Clock on nRF51822?

Håkon Alseth — Tue, 16 Jul 2013 11:00:04 GMT

Hi,

Are you going to use a timer to track time? Like having a variable that shows minutes/seconds/ms/etc?

If you use the app_timer library, you can setup functions that are called every x millisecond. Using this you can setup a global variable that is incremented (in the app_timer callback function) each time it's called.

Best regards Håkon