Zigbee UART connection from MAX232

Thread Starter

Wavelength

Joined Mar 2, 2006
13
Hello, sorry if this already posted but I can't seem to find it.

I'm have PIC16F873A connection to a max232 chip and connect it to my PC RS232 port. I am able to read and the data from my hyper terminal the intended data from my PIC just fine :)

My plan is know to use Zigbee to make the project wireless. I intend to still use the PIC and the max232 on the project and just connect it to the ZIGBEE UART port. I know zigbee have a UART pin for serial communication.

My question, will there be a need to have a chip which change the voltage level of the serial data coming from my PIC trough the RS232 before I can connect it to the Zigbee? Because from the data sheet I can see that Zigbee have a max input of 3.3V and the voltage level from the max232 would be different or it doesn't matter? I still waiting for my Zigbee module to arrive so I can't play around with it yet .:(

Anyway thanks in advance :)
 

t06afre

Joined May 11, 2009
5,934
Hard to say without some more information. Do have a link to the data sheet, or the full type number for your ZIGBEE device
 

alphacat

Joined Jun 6, 2009
186
Hey.

I'm basically doing what you describe.

I have an Uc which receives messages from PC through its RX and TX pins, and these messages are transmitted wirelessly using ZigBee protocol.

I'd love to help you but as was said here, more details are needed.
You can send me a PM with your msn account and we can discuss it :)

See ya.
 

t06afre

Joined May 11, 2009
5,934
Hey.
I'd love to help you but as was said here, more details are needed.
You can send me a PM with your msn account and we can discuss it :)
I think all people visiting this forum should be able use the result from your discussion. So please continue the discussing in the forum. No need to go private in this case.
 

Thread Starter

Wavelength

Joined Mar 2, 2006
13
Thanks for the reply :)

The Xbee is a 20 pin with chip antenna which is from Digi.I'm not sure about the chip manufacturer but from the PDF it seem its from Ember. Anyway it was actually included in BL4S100 SBC from Rabbit Controller. I was thinking to just take the Xbee module and implement it for this wireless idea. :)

I attached a PDF about the Xbee module.

R201WW0721575
XB24-Z7CIT-IO59-revB
2008-12-11-19
 

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t06afre

Joined May 11, 2009
5,934
From page 14 in the data sheet, I would say that a MAX232 is not needed if you want to connect the ZIGBEE to the PIC. But I guess both have to use 3.3 volt as supply voltage on the PIC
 

John Luciani

Joined Apr 3, 2007
475
The XBee is RS232 at 3.3V TTL levels. If you have to run your uC at 5V
then either a resistor divider or an AHC buffer will work (AHC has 5V tolerant
inputs).

IIRC the XBee series two is Ember radios. I believe the Series I is Freescale
radios. Also I do not believe Series I and Series II can be mixed.

If you are doing a very low power system that will put the XBee in sleep mode for
long periods of time you may want to consider running the XBee at 3V. The current
in some of the sleep modes is dramatically reduced. I did a little Zigbee writeup with an XBee power example. See http://wiblocks.luciani.org/white-papers/intro-to-zigbee.html

If you decide to use an Atmel uC checkout my board that integrates an ATmege328
with an XBee on a single PCB. http://tinyurl.com/5rfmrz

(* jcl *)
 

t06afre

Joined May 11, 2009
5,934
Using a 5 volt tolerant buffer is a good idea. You have 3 types in the 7400 series that can do that.
75LCX - CMOS with 3V supply and 5V tolerant inputs
74LVC - Low voltage - 1.65 to 3.3V and 5V tolerant inputs, tpd<5.5nS@3.3V, tpd<
74LVX - Low voltage - 3.3V with 5V tolerant inputs
 

Thread Starter

Wavelength

Joined Mar 2, 2006
13
Thanks for the input. Sorry guys for the late reply went for an outing yesterday. :D

So I can just supply my pic and the max232 with 3V supply voltage and the output will be compatible for the ZigBee 3.3v TTL input ? Guess so since the PIC and the RS232 output is reference to the supply voltage please correct me if I'm wrong. Looking from the PIC data sheet it can work using 3v supply but the max232 need 5v for minimum supply.

Anyway I don't want to change the supply voltage and removing the max232 for the mean time.Maybe later on I can swap the 5v regulator for a 3v regulator and make another circuit.:)

So now I'm going to use resistor divider or an AHC buffer solution. But I guess I will try with the 5 volt tolerant buffer first. I will post the update on how its goes hopefully I will get the development kit for the Xbee this week . Thanks to t06afre and John Luciani :)
sheet

I attached the PIC data sheet I'm using the 28pin PIC16F873A.
 

Attachments

hi,

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