AF_DataRequest strange issue

Ilya Sokolov1

Other Parts Discussed in Thread: CC2538

Hello.

I'm trying to transmit ADC data flow using ZStack.

My end device initializes ADC and after it connects to the network starts transmitting data. Data are sent in packets of 78 bytes (3 channels, 2 bytes per sample, 13 samples in packet).

My coordinator receives the data and sends them via UART to the main microcontroller.

At some time coordinator have to send commands - for example command of changing sample rate. These commands are successfully sent and received, but only if sample rate of the ADC is below 128 Hz.

When sample rate is above 128 Hz command is not sent by the coordinator, but call of AF_DataRequest returns zero (ZSuccess).

Sniffer file is attached. Capture_5.psd During the capture I've changed sample rate one from 100 Hz to 40 Hz, then from 40 Hz to 203 Hz, and then tried to change sample rate from 203 Hz to 40 Hz back. But the last command was not sent by the coordinator.

What can be reason of such behaviour?

over 8 years ago

0 YiKai Chen over 8 years ago

Guru 735695 points

I think it hit the floor of data rate if you use sample rate larger than 128Hz.

0 Ilya Sokolov1 over 8 years ago in reply to YiKai Chen

Intellectual 840 points

But with the based on the CC2538 Foundation Firmware(www.ti.com/.../CC2538-SW) which sends MAC-level packets I managed to get 1600 Hz sample rate.

I understand that there are MAC answers in ZStack, and the number of samples in packet is decreased from 16 to 13, but I didn't expect such extreme decrease of sample rate.

What can I do to increase the data rate?

Also what are reasons of such data rate decrease?

0 YiKai Chen over 8 years ago in reply to Ilya Sokolov1

Guru 735695 points

If you configure your device to router, it can increase data rate.

0 Ilya Sokolov1 over 8 years ago in reply to YiKai Chen

Intellectual 840 points

Thank you.
I'll try it.
But what are causes of such data rate decrease?

0 YiKai Chen over 8 years ago in reply to Ilya Sokolov1

Guru 735695 points

Because receiver of end device doesn't always turn on and it will cause data rate is worse than router.

0 Ilya Sokolov1 over 8 years ago in reply to YiKai Chen

Intellectual 840 points

And is there way to get receiver of end device to be always turn on?

0 YiKai Chen over 8 years ago in reply to Ilya Sokolov1

Guru 735695 points

You can define RFD_RCVC_ALWAYS_ON to TRUE in compile options.

0 Ilya Sokolov1 over 8 years ago in reply to YiKai Chen

Intellectual 840 points

Thank you, it works.

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AF_DataRequest strange issue