Use of MAX232 IC

[Jaden Ng]

Hi,

 

I just read 2 of the articles

http://www.engineersgarage.com/embedded/pic-microcontroller-projects/rfid-interfacing-circuit-code

http://www.engineersgarage.com/microcontroller/8051projects/interface-rfid-AT89C51-circuit

 

 

I’m abit confused with why the pic18 dont need a max232 IC when rfid communicate with controller but why the AT89c51 need a max232 ic.what is TTL btw?

[nikhiljain]

very good question Jaden. If you’ll look at the Images of both the projects on their first page, you’ll notice that in case of AT89C51, the RFID reader is mounted on a PCB which itself contains a MAX232 and converts TTL to RS232 logic. While in case of PIC18, the RFID reader is directly connected to the microcontroller on the breadboard and gives TTL logic straight away.

In case of AT89C51:

[RFID Reader (TTL) –> MAX232(RS232)] –> MAX232(TTL) –> Microcontroller

 

In case of PIC18:

[RFID Reader(TTL)] –> Microcontroller

 

The Square bracket represents RFID Module in both the cases. So you can use either of the configuration in any of the case, only thing you need to take care is that you provide TTL logic to the controller.

[Aviral Sharma]

thanks for the explanation nikhiljain.

[Author]

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