Anyone can suggest ZigBee protocol for collecting continuous data upto 200Hz from sensor.

Hi someswara,

If your zigbee output interface can be configured as USB, I suggest a USB to SPI converter going to M.C.U. will be the better solution to this.
Please see link below for the device you can use to interface this.

www.silabs.com/.../usb-to-spi-bridge.aspx

Good Day
Leo

Do you mean to transmit data over the air upto 200Hz with Zigbee protocol?

Hi YK Chen,

It will depend how much is the size of the data and type of data he wants to transmit in 200Hz.
A typical zigbee can transmit 250kilobit /sec of data. That would be 31250 byte per second.
For the table of data rates, please see below:

www.convert-me.com/.../dkilobitps.html
www.google.ch/.../US20100202564

Leo

I know It depends how much is the size of the data and type of data he wants to transmit in 200Hz and that's why I am asking.

Hi YK Chen,

Do you mean the zigbee's frequency band of transmission you want it to be 200Hz instead of 2.4GHz?

Leo

Hi Leo,
I am not asking you question and I am not the one who asks this question. I am asking someswara to clarify his problem so we can help him.

Hi someswara,

Theoretically if you intend to do transmission of data at the sampling speed of 200Hz, getting the time will be equivalent of 0.005sec. Relating this to the bitrate of zigbee which is 250kilobit per sec (31250bytes per second) approximately you are able to transmit sensor data size maximum of 156bytes (156.25).

It is possible to transmit, just don't exceed this byte count to be transmitted that I mentioned. The sensor data can be digitized with 8bit, 16bit, 24bit wide so on and so forth. It's 156bytes transmitted at 0.005sec. So no missing or wrongly shifted bits will be encountered when you are to intepret the sensor data with calculation formula.

Leo

According to my experiences, you won't be able to transmit 156bytes transmitted at 0.005sec. This data rate is too high for Zigbee application layer.

Hi YK Chen,

So from your statement transmitting 250kbps @ 2.4GHz is not attainable as per the specs?
If we rephrase the question, If I'm going to fully utilize the 250kbps data rate at ideal condition, how many bytes I can see at 0.005sec?
What is your maximum byte count and speed attainable based on your experience?
Just an inquiry.

Leo

If you send data from ZED to ZC, it can be upto around 16k bps at most.

But how much data will you send each time?

And another question; do you have requirement on mesh? If you just want to send some data with 200Hz it might be better to either use 802.15.4 directly (TI-MAC) to minimize the overhead you would have with the network and application layer (I would guess this is the reason to the 16kbps limit Yikai mentioned). 

If you tell the application behind this question it might be easier to help.

Hi someswara,

The closest Mr. Yikai (16kbit/s) said is the 20kbit/s if you are using the 868MHz Zigbee frequency.

I'm also curious why they advertise the 250kbit/s at 2.4GHz Zigbee frequency which theoretically can cover the 200Hz data sample rate.

By the way, what is the digital data that you are going to transmit over the air then and it requires 200Hz data sample rate? 

Best Regards,

Leo

Leo, I think there are more aspects;

802.15.4 can send one frame (and the frame length is maximum 128 bytes and depending on security and such the amount of data is actually less 82 byte with nwk and no app security if we talk about ZigBee) with 250 kbit/s the whole mac-nwk-app-layer takes time as well.

And after each frame, the receiver need to ACK that, it takes time as well. In addition the receiver will need to look at the network header; was this meant for me or someone else? If it was meant for the receiver it has to decrypt the network payload and look at the application header and make sense of that. So there is quite a overhead added if we talk about the layers between 802.15.4 and ZigBee application layer.

The 250 kbit/s applies on 802.15.4 - depending on what you use that for (perhaps a ZigBee network) it will affect the throughput as mentioned above. If a high throughput is needed but not range and mesh, I would look at 802.15.1. If high throughput and range is needed I would look at Wifi. If high throughput, range, and mesh is required; I wish you good luck.

Hopefully this gives a more clearer view of what one need to consider when designing their network, everything has its pros and cons :)

Hi Mr. Frederick/Mr. Yikai,

Good explanation, this is clear now.
At first glance of this Zigbee data rate, its quite amazing.
I just newly used this also and benchmarking also.
The data from my sensor is not so big so I cannot see the latency.

Hi Someswara,

Is averaging the sensor data to be transmitted with your zigbee application allowable? Instead of sending the whole live 200Hz data through the zigbee, average this readout inside the M.C.U. Or device To make the data meaningful if that is a sensor data sampled in 200Hz cycle then transmit the average by zigbee in a normal allowable time interval. Just a suggestion.

Leo

It's good to know it is clear now. You should keep in mind that Zigbee is for low power and low data rate application.