serial communication using USB?

Development Boards MicroMod
1

Hi

According to datasheet and application notes of AVRs, We can do serial communication (RS232) with just the following functions:

void InitUART(void);
void transmitByte(void);
ReceiveByte(void);



void main(void)

{

	InitUART(void);
	transmitByte('A');

}



void InitUART(void)

{

	...

}




void transmitByte(void)

{
	...

}




ReceiveByte()

{
	....

}

My question:

Is there any AVR application notes that tells you how to do serial communication using USB? I understand that USB is much more involved. But I was wondering if any body has some basic, small and understandable functions that allow communication using USB. Thanks

.

2

Doing USB in software is difficult, and the MCU can’t do much else. Atmel has an app. note on it.

Leon

3

leon_heller:
Doing USB in software is difficult, and the MCU can’t do much else. Atmel has an app. note on it.

Leon

How to do it in hardware then? I noticed that for RS-232, they always use MAX232 chip or something like that. Is there any chip to use? Thanks

4

You can throw on a logic level to USB converter chip on it. Popular ones are the FT232R from FTDI. It requires basically no external components and can work with 5V and 3.3V logic-level serial. In Windows/Linux/OS X it simply appears as another serial (COM) port.

5

theatrus:
You can throw on a logic level to USB converter chip on it. Popular ones are the FT232R from FTDI. It requires basically no external components and can work with 5V and 3.3V logic-level serial. In Windows/Linux/OS X it simply appears as another serial (COM) port.

What about software? Is any kind of programming invovled with this chip? Any example of it? Thanks

Regards

6

No software needed, it behaves to your microcontroller as a normal serial port. Same for the PC side.

Look at the datasheet (many example schematics), or SparkFun’s breakout modules for this chip.

7

There are MCUs with USB, like the PIC18F2450, and some AVRs. They aren’t difficult to use.

Leon