Hi i’m hemanth…i’m doing a project on remote controlled milli second timer using 8051 micro controller(P89V51RD2 from philips). i’m using zigbee for communication to send control signals like the start/stop…set…reset… ethin is fine i ve written code to take values through serial n do opertaion… if i connect zigbee for communiction between console n timer out of 10 times only twice r thrice timer stops r starts…so can u pls help me regarding this problem…i tried wired serial communication using serial cable between these two it works perfect…i’m using a standard baud rate of 9600bps…i hav even checked source n destination address…no problem with it… i tried wrintin a simple code to glow an led when i press a switch on other mcu…out of 10 times twice or thrice the led glows when i press the button
i’m using xbee series 1, XB24 version 1024
can any 1 help to solve this prob as i need to submit the project within 2 days…
i hav a doubt dat xbee might be getting reset so what is the sol if its getting reset.
Well first, a series 1 module with version 1024 firmware is NOT ZigBee. It is running the 802.15.4 protocol. Also firmware 1024 is rather old but it would still work.
I can only guess at possible problems.
Since it work sometimes it could be a baud rate timing error. What is the the 8051 using for a clock? XTAL, cer resonator, RC?
The XBee reset line has an internal 50k Ohm pull-up so if that line is not connected or only connected to a switch then I can’t see how the XBee could be getting reset.
ZigBee is licensed, proprietary, and needed only if you are wanting full mesh networking (hopping). In Digi’s products, series 1 support 802.15.4 where you either use a star topology with a coordinator or use no-coordinator, peer to peer similar to ad hoc mode in 802.11. DigiMesh runs on Series 1 as well. It’s better than ZigBee, IMO.
Hi waltr n stevech thanks for ur reply. i’m using 11.0592 crystal which has 0% baud rate error. the problem wat i’m facing is if i connect 2 xbee’s with rs232 interface to 2 separate pc’s n type a number from 1 to 9 i can receive only part pew numbers out of it. i mean even if i transmit 32 bits of data or 8 bits of data continuously i’l receive the 8bit r 32 bit data but not continuously. hope u undrstood ma problem…if u r familiar wth xbee pls help out in solving this problem …n i jus want to transmit data from one point to another i don wan to build any star r mesh network.
I’m not as familiar with the series 1 XBee’s as Stevec so I hope he’ll jump in to either give more info or correct what I say.
An XBee serial port (DIN. DOUT) has an internal buffer. When data is sent into the port it goes into the buffer and at some time it is packetized to be send over the RF link. There are parameter settings to configure when the packetizing takes place. This is where I would be looking.
Also relize that the data is packetized so if you send a bust of data into the serial port it may not arrive at the same time and if is possible that it arrives out of order due to a packet needing to be re-sent.
Thats another parameter to check; there is a value of the number of re-transmissions and re-transmissions can even be turned off which could cause lost data.
Do you have any other 2.4GHz devices nearby like WiFi? There may be some interference causing lost packets.
Also be sure the XBee’s are in AT command mode (also called transparent mode).
I’ve used the series two XBee’s at high data rates and other use the Series 1’s without problems. So there is a likely explanation.