Bita Sobhani

URGENT********** ATD sampling frequency ************PLEASE SOMEONE REPLY - zigbee Mc1321x

Discussion created by Bita Sobhani on Sep 23, 2008
Latest reply on Sep 23, 2008 by Daniel Lundin
Hi all
I am working on zigbee Mc1321x.
I need to send ATD samples from a node to coordinator. I encountered these limitations in zigbee mesh networks:

1-    ATD conversion clock can vary only between 500Khz to 2Mhz.

2-   Rate of sending packets can not be exaclty determined. It depends on network traffic. This is because the next packet can not be send until sending confirm of the previous packet is received.

3-   Maximum payload length is 98 bytes (without fragmentation).

4- timers can not be less than 4 milliseconds (250Hz)

Since ATD conversion clock is too high, I can't send samples as they are produced (because of packet rate limitation).
Buffering of samples does no work as well, because of payload length limitation. (for example if ATD frequency is 500Khz, buffering requeires a packet rate of 98*2=196 microseconds. This packet rate is high for even a very small network. Also fragmentation can not do anything.
If I use a timer for ATD sampling, frequency can not be more than 250Hz.

Despite these limitations, how can I reach high sampling frequencies?

Added p/n to subject.

Message Edited by NLFSJ on 2008-09-24 01:36 PM