CC2531: Estimating Power Usage for battery device with Zigbee

Josh Ferguson35

Part Number: CC2531
Other Parts Discussed in Thread: Z-STACK

Hi,

I'm trying to understand how the CC2531 communicates with a zigbee hub. In this case I will be using the new Echo Plus with zigbee built in as the hub.

When the hub gets a ON command, does it send a broadcast to the zigbee address and hope it received it? If so, does the zigbee device need to be always on?

Or, do I put the CC2531 into sleep mode and wake every few seconds to ask the hub if there are any pending commands.

Sorry for the basic question, I'm just trying to wrap my head around this.

I see that the CC2531 draws about 20ma while on, which would kill a battery pretty quick if it needs to stay on 24/7.

Thanks!

over 8 years ago

0 YiKai Chen over 8 years ago

Guru 735695 points

We usually use unicast when sending messages with Zigbee. If you need low power application on CC2531, you should use end device configuration and set proper polling rate to receive meetings for end device.

0 Josh Ferguson35 over 8 years ago in reply to YiKai Chen

Prodigy 40 points

Thanks for your answer.

Could you please elaborate on polling? For example, what happens is the chip is in sleep mode when a command is sent from the Zigbee hub? Is it lost, or is it sent repeatedly until the device receives it?

How long does it take the chip to come out of sleep mode to check for commands?

I'm trying to figure out how long this device can run on a single 18650 battery.

Thanks!

0 YiKai Chen over 8 years ago in reply to Josh Ferguson35

Guru 735695 points

The message would be kept on parent node of end device for a while until end device wakes up to polling it or the message might be timeout if device doesn't wake up for polling for a long period. Polling rate is configurable by POLL_RATE define in f8wconfig.cfg.

0 Josh Ferguson35 over 8 years ago in reply to YiKai Chen

Prodigy 40 points

Do you know how long it takes the chip to come out of sleep and check for messages?

0 YiKai Chen over 8 years ago in reply to Josh Ferguson35

Guru 735695 points

I replied you it’s defined by POLL_RATE and it is 1 second by default in Z-Stack.

0 Josh Ferguson35 over 8 years ago in reply to YiKai Chen

Prodigy 40 points

I'm looking at page 4 of this datasheet:

www.ti.com/.../cc2531.pdf

If I wanted it to sleep and then wake up every 6 seconds, what mode would it be in for sleep?

0 YiKai Chen over 8 years ago in reply to Josh Ferguson35

Guru 735695 points

PM2.

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CC2531: Estimating Power Usage for battery device with Zigbee