Hi there,
I am evaluating a few different RTCs (external 32KHz clock) for my system. I would like to set up a timer that uses RTC clock, put the system in extended/deep sleep, wake up the system with the timer, toogle a GPIO pin then repeat this process. Do you have such a sample code available? I assume RTC selection won't affect BLE since it uses 16M clock, correct?
Thanks
Hao
Device:
Hi jet_hao,
I am not sure what you mean with RTC. The 580 operates with a mandatory XTAL16 and a sleep clock that could either be an XTAL32 or the RC32 which is the internal oscillator. When sleeping the 580 has its peripherals in power down so you wont be able to use a timer. There isn't an official example that will match your description but you can easily implement one by using a kernel timer. As previously mentioned the 580 uses both the XTAL16 and the XTAL32 (mandatory in boost mode) or RC32.
Thanks MT_dialog
Hi MT_Dialog,
Thanks for replying. RTC means real time clock. It's usually means an external 32KHz clock. When referring to DA14580 datasheet section 4.8.1, "The 32.768 kHz oscillator has no trimming
capabilities and is used as the clock of the Extended/Deep Sleep modes." It's not very clear to me what is left on in AON domain mentioned in the datasheet. If there is no bare metal example, I can play with kernel. Sorry for one more dumb question, do you have restrictions/recommendation on the 32KHz clock?
Thanks
Hao
Hi jet_hao,
An example on bare metal for the operation that you ve requested doesn't exist, the XTAL32 or the RCX stays awake while the 580 goes to sleep, regarding the restrictions/recommndations you can have a look either at the datasheet for the recommended operating conditions for the XTAL32 on table 286, or you can check the BOM in the reference designs and the dev kits that use an XTAL32 on the reference design section of the support site.
Thanks MT_dialog
Hi MT_dialog,
Thanks for your answer. May I ask what generates BLE 0.625ms ticker? Is it either xtal32 or RCX depends on my setting? I would assume if I disable both of them, then the system won't wakeup, correct?
Thanks
Hao
Hi Jet_hao,
Actually only the XTAL16 crystal is the one that keeps this tick active, the RCX oscillator or the XTAL32 crystal (depends on your setting) are keeping this base counter register updated while the 580 sleeps (when the 580 is in not in sleep mode the timer is running, but when in sleep mode the amount of time that the 580 sleeps is measured by a different counter that counts the sleep time in low power clock cycles). As soon as the 580 wakes up, due to the wake up interrupt, the 0.625ms base counter register will be updated with the compensated value of the low power clock counter. And yes if you ommit the LP clock you wont be able to wake up since there will be no increment for the register that counts the lp clock cycles.
Thanks MT_dialog
Hi MT_dialog,
We need to feed DA14580 with an external clock. We tried an Xtal and a SiTime part SiT1152. Xtal works seemlessly. However, SiT1152 does not cooperate very well. We tried to connect the SiT1152 to pin 12, after connection, we can see both pin 11 and pin 12 has a good 32KHz clock. The voltage level of SiT1152 is 500mV low and 2500mV high. Which is obviously different from a xtal32. Is there any register I need to tune by using an external SiTime clock connect to xtal32p pin only?
Thanks
Hao
Hi jet_hao,
Please check the following related posthttp://support.dialog-semiconductor.com/sdk-50x-usage-external-32khz-clo...
Thanks MT_dialog