Author Topic: MC205 datetime.now() resets at boot time  (Read 64 times)

eric

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MC205 datetime.now() resets at boot time
« on: November 22, 2017, 04:00:42 pm »
Problem: When the device is power-reset (jumper off-on), the shared function DateTime.now() resets to zero. Consequently any code running with reference to the time of the day becomes impossible to implement. In my practical configuration, the device is not connected nor connect-able to a gateway at that re-boot moment (it may be in the field by itself), however, it is in a Sigfox covered area.

Question 1: Is there a way to access the Sigfox time reference on board the device, so that the device can figure out what time it is ? My understanding is that when the device sends a Sigfox message, it sends a reference to that sigfox timestamp in the header (together with Sigfox ID) so that the sigfox network can calculate how many seconds have elapsed between device emission time and back-end notification time. Please correct me if my understanding is incorrect.

Question2: I understand the MC205 does not support Sigfox downlinks (messages from the cloud to the device) because of high power consumption. However, this could be used to anchor the device datetime reference after booting in the field, it would be only one message per boot cycle and could by itself justify making downlinks available ... Will downlinks become available in the future for MCdemo 205 ?

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mc-Abe

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Re: MC205 datetime.now() resets at boot time
« Reply #1 on: November 23, 2017, 10:13:03 am »
Unfortunately there is no way to persist time on the mcDemo205 across a reset at the moment. We are working on improving this but the problem is trickier than it might appear on the surface.

As for your questions:
1. There is no such thing as a sigfox timestamp. All timing information is handled by the base station.
2. There are no plans at the moment to support sigfox downlink on the mcDemo205. The device is only certified for uplink by sigfox.

Another update coming soon is the ability to set the device time which on an mcDemo205 can be retrieved from the on-board GPS if a fix can be acquired.

eric

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Re: MC205 datetime.now() resets at boot time
« Reply #2 on: November 24, 2017, 12:07:03 am »
Thank you MC-Abe, for your quick response. Please notify me when a technique is available to get the device to know the time from a GPS fix, because that will practical and accurate in our case. The idea was also generated here during a brainstorming session, so we're happy to help make it happen sooner than later. Any idea how we can help ?