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about using max232 in 89c52

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visva

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why in serial communication the max232 need to use in micro controller. if there is no max232 then can we send data in serial. please any one explain
 

max232 is an ic which converts the +5v signal of uC into standard RS-232 levels of signal, which are +/- 12v.

you can of course use serial comms without max232, but do not try to connect it to a standard rs232 cable/ port, otherwise your uC will blow.
 
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    visva

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why in serial communication the max232 need to use in micro controller. if there is no max232 then can we send data in serial. please any one explain


Its simple RS232 have signals 24V and TTL 5V.

RS232 vs TTL Signal.PNG


This chip converts RS232 signal voltage levels to TTL voltage levels and visa-versa, hence if you need to communicate to your PC through it's serial port (COM1 or COM2) then this is the chip that can perform that function. If you have a microcontroller circuit, or a phone, or a calculator that requires a PC connection then this is the chip that is needed to make that communication happen.

The RS232 serial port protocol (v.24) states -15v to represent binary 1 and +15v to represent binary 0. For TTL communication this is incompatible since TTL uses 0v to represent binary 0 and +5v to represent binary 1. MAX232 chip converts serial signal voltage levels to TTL standards, and also vias versa. It therefore has a driver and a receiver to perform this function.

https://www.petervis.com/electronics guides/MAX232/MAX232.html
https://www.edaboard.com/threads/91287/
https://en.wikipedia.org/wiki/MAX232

**broken link removed**


This conversion can be done with transistors.

Two transistors RS232 Level Converters.jpg
 

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