CAn anyone tell me how do i use UART?

[ABSF]

Baud rate is nothing but the speed of data transfer. Just similar to the speed of typing. Some typist can type very fast and some very slowly. In data communication if the sending speed is 900 bytes/second and the receiving side can only receive at 100 bytes/second, The receiver would not be able to understand what the transmitter is talking about. That's why the sending speed must be the same as receiving speed (synchronisation).

Since sending a byte needs about 10 bits (1 start bit, 8 data bits and 1 stop bit). At 9600 buad means 9600 bits/second which is about 960 bytes/second.

Allen

[davidtsj]

Dear ABSF,
Thx for ur help...btw do u know the schematic connections in order to connect xbee to PC using UC00A.. how the connections work as i afraid i might burn the xbee or corrupt my PC (Cautions: “+” on UC00A is 5V supply directly from USB port of computer; it is advised not to use this power source to power application circuit or device. Wrong connection
such as wrong polarity, wrong voltage, shorted might permanently damage computer.) the UC00A manual only shows UC00A device connect to PC..it does not show how it is connected to PC together with xbees..thx in advance..any advise will be much appreciated...

[ABSF]

You have most of the answers you wanted in the other thread by "yong hui" and "robosang".

To interface your XBee to UC00A, not only involve the Vcc problem of 3.3V (XBee) and 5V (UC00A). It also has the problem of level shifting from 3.3 to 5V and vice versa between XBee and UC00A. The signals are refering to DOUT, DIN, RTS, TX, RX etc.

Using voltage divider to interface might not work as indicated in this link:

http://www.mikroe.com/forum/viewtopic.p ... rt#p124215

Level shifters are chips like 74LVC4245A or 74LVC07 or using MOSFET BSS138. The simplest is the use of mosfet with 2x10K resistors as



This setup is bi-directional so it works bothway from xbee to uc00a and vice versa. May be others with experience on this topic can help you better. Google for "3.3v to 5v level shifter circuit" to get a description of how it works.

Allen