Low power mesh with Digimesh S2C modules

XBee & XBee Gateway XBee - DigiMesh
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Hi,

I want to build a low-power mesh so I decided to use Digimesh that allows sleeping for all nodes.
My plan is to use cyclic sleep to wake ~10 modules with sensors and no u-processor attached.
One of these modules (almost same sleep scheme), connected to a Raspberry, would collect data from standalone modules.

Wake time would be a few seconds.
Sleep time would be 15 minutes.

Now I have three Digimesh 2.4 S2C modules and I cannot find a way for the modules to :

  • wake (almost) synchronously,
  • send a frame with ADC values and IOs state to Raspberry module
  • return to sleep
    while keeping an accurate 15 minutes period.

Asynchronous sleep mode is useless : with a wake+sleep (ST+SP) time of 15 minutes, frames are transmitted each ~14.6 minutes.
So standalone modules will quickly be out a phase with the one that collect the data.
I will not try to ‘calibrate’ the difference between 15 and 14.6 minutes as it may change with module, number of modules in the mesh, amount of data, etc…

Digimesh S2C modules does no more support the synchronous sleep of old, legacy S1 modules, which was a huge benefit.
So, what is the way to build a mesh where all nodes can sleep, and wake with a well defined period ?

I’m pretty sure Digi engineers have a workaround to do that, unless they would have keep synchronous sleep in S2…

Thank you !

PierreRF.

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No, Digi Engineers don’t. You see the processor on the S2C simply is not accurate enough to support a Synchronous sleep. That is why it is not there. The option at this time is to use the XBee PRO 900 HP, XBee/XBee PRO SX or XBee SX 868.

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Okay, thank you mvut for your reply.

I think I was wrong when relying on a proprietary protocol like Digimesh.
Digi can do what they want with its specs & functionality, like killing the synchronous sleep mode…

PierreRF