Receiver,transitter, rfid module conection to uc

[geethucmohan1992]

I am doing a project on RFID based shopping cart...but now am having a few problems. I am having trouble connecting RFID module to the microcontroller(AT89S52) am using.
The RFID module i purchased consists of EM-18 reader module and it has been connected to max232 and then to RS-232...so the module has rs232 output..now can i connect directly from rs232 to tx pin of microcontroller? or is there another way?
the following site says use max 232 and then to uc. but i have rs232 output..so how to?

**broken link removed**
i have attached the picture of my rfid module

Also, I have a transmitter for which am using MO-SAWR-ASK transmitter. That is to be connected to my microntroller (AT89S51). Is it ok to connect its data pin directly to the Tx pin of uc?

And the receiver OX-RX02-ASK recieves the data and this is to be connected to a second microntroller. Can i directly connect its data pin to Rx pin?

I also have to recieve the same to a PC or laptop. Now a days laptops dont have RS232 port, so how to receive the same in pc? can i use a 3rd uc, so that receiver is connected to uc, then to max232 then rs232, but then how to connect from rs232 to pc/laptop?

 

[jayanth.devarayanadurga]

No you can only connect TTL level 5v or 3.3v (depending upon the device) to mcu. rs232 voltage is beyond that range. You have to use another max232 between mcu and you rfid's rs232 connector or if you can put wires at the input side of max232 on the rfid board then that can be cross connected to mcu directly. If your ASK transmitter and receiver gives TTL o/p and i/p then you can connect it directly to mcu. Does your mcu have two UART? one for ASK module and one for rfid is needed.

 

[geethucmohan1992]

Thank u so much for replying.
No my mcu has only one Rx and Tx pin. But the Rfid module is to be connected to the Rx pin via max232 and transmitter to Tx right. So is it alright. Because the receiver is being connected to a second mcu.
If my transmitter and receiver doesn't have TTL o/p, how do I connect it to mcu?

Also the receiver connection to pc/laptop..

 

[jayanth.devarayanadurga]

Which MCU are you using? PIC, AVR, 8051? Mention the mcu like PIC16F887 or ATMEGA16. What is the baudrate of rfid module? What rfid module are you using? What Compiler and language do you want to use for the coding? Post a datasheet of the rfid module.

Edit: Ok. You are using AT89S51. I dont know if you can do software uart with it. Find if you can do software UART with your mcu. I think you can do that. Use software uart for rfid or ask module.

I can see in your RFID module image that two pins of rfid is connected to JP1 and also to pins 12 and 13 of max232. You can take the TTL level from pin 13 of max232 or the 1st pin of the JP1 which is connected to max232 pin 13 and also to rfid chip. You can connect pin 1 of JP1 to MCU Rx pin directly, then you don't need another max232 between mcu and rfid module.