BLE Stack v1.3, Timers, Interrupts and sending data to the iOS app...

Ben Scammell

Sorry for the long title.

This is all in relation to CC2540DK-MINI Keyfob.

I am hoping for some best practice advice on making some modification to the v1.3 stack.

1. We would like to maintain powersaving, but we need a 1ms increment accurate 32-bit timer, which is persistant from boot, through powersaving and accurate to 1ms.

2. We would then like to snapshot that timer when an interrupt is generated by pressing one of the two keyfob buttons.

3. We would then like to send that 32-bit int to the iOS app, within 100ms.

Please can the all-knowing pros & expert TI staff give me a hand here, at least point me in the right direction.

Thanks in advance!

Ben

over 12 years ago

0 Aslak N. over 12 years ago

TI__Mastermind 23440 points

Hi,

You could set an OSAL event in the ISR, and in the handler for that event, call osal_GetSystemClock() (OSAL_Timers.c) which will have been updated at this time.

Best regards,
Aslak

0 Ben Scammell over 12 years ago in reply to Aslak N.

Intellectual 620 points

Thanks!

What is the precision of the system clock?

0 Ben Scammell over 12 years ago in reply to Aslak N.

Intellectual 620 points

Could you provide me any example code? please :-)

0 Aslak N. over 12 years ago in reply to Ben Scammell

TI__Mastermind 23440 points

Hi Ben,

The precision is 1ms. The accuracy is perhaps what you were asking about, and that depends on the central device, as every time the peripheral wakes up for a radio event, the system timer is corrected using the event as an anchor point. Thus the accuracy depends on the tolerance of the crystals used.

For example code see for instance hal_key.c.

Best regards,
Aslak

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BLE Stack v1.3, Timers, Interrupts and sending data to the iOS app...