MCU programming using MAX232

Thread Starter

prakhars

Joined Oct 4, 2011
4
Is it necessary to use MAX 232 IC for AVR Microcontroller programming.????

Because i have seen many programmer circuits that on programming with RS 232 protocol uses MAX 232 and there are also many that without using any intermediate IC, programs the circuit simply by connecting some resistors and transistors in between the serial port and the MCU.
 

MrChips

Joined Oct 2, 2009
30,714
The MAX232 or any RS-232 to TTL converter chips are not absolutely necessary.

The output from a PC COM port is typically about +/- 10V but can be anything from +/- 5V to +/- 15V.

The purpose of the MAX232 is to convert those +/- voltages to TTL levels, usually 0 to 5V, in both directions (receiver and transmitter).

You can accomplish the same thing using resistors and transistors.
 

Thread Starter

prakhars

Joined Oct 4, 2011
4
So it doesn't mean that the use of MAX232 is must.
We can use RS232 port directly for any of Microcontroller,.......
 

MrChips

Joined Oct 2, 2009
30,714
If you wish to connect one MCU to another MCU you do not have to use RS-232.
You can connect the SCI TTL signals directly.
 
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