16f628A - RS232 direct to PC serial port (without max232) - Page 2 - Electronic Circuits Projects Diagrams Free

eng1 · 18th August 2006, 07:31 PM

Quote:

Originally Posted by Mr.Anderson

In short, for a 9600 baud, each bit should delay for 104us and all the bits need to be inverted logic if you compare them to what would be the right logic statuses for standard RS232. They need to be inverted since the voltage levels are not the same between RS232 and TTL levels.

I understand this. But I can't understand how the serial communication between the PIC and the PC can be reliable with 0 and +5 V levels. Does your circuit work properly with those levels?
Thanks

**Nigel Goodwin** · 18th August 2006, 08:07 PM

Quote:

Originally Posted by eng1

I understand this. But I can't understand how the serial communication between the PIC and the PC can be reliable with 0 and +5 V levels. Does your circuit work properly with those levels?

It's a perfectly valid method, and has been used for many years - it's how the BASIC STAMP works, and was the subject of a Parallax application note even before the STAMP was produced.

Not that I'm suggesting that Parallax came up with the idea, I suspect it's far older than that!.

Mr.Anderson · 18th August 2006, 08:34 PM

This stuff was just not too mentioned until now. I've found some information but not found all in one place. My tutorial expects to explain what was not clear to me before and help others.

yomero_romero · 30th October 2009, 02:15 AM

mr anderson: too bad you asked for help and people helped you...and when someone ask you for help you refuse to help...don't give up all your code but just the part that mimics the USART with software

Mr RB · 30th October 2009, 05:50 AM

I have projects on this page that sends and receives serial between a PIC 18F1320 and PC serial port, using just 2 resistors. All source code is included (in MikroC), and it uses a very simple nifty bit-bang system with the PIC timer that can be done on any PIC;
Connect JuneBug to serial port and Sharp GP2 sensor

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18th August 2006, 08:34 PM	#18
Mr.Anderson	This stuff was just not too mentioned until now. I've found some information but not found all in one place. My tutorial expects to explain what was not clear to me before and help others.

30th October 2009, 02:15 AM	#19
yomero_romero	not nice mr anderson: too bad you asked for help and people helped you...and when someone ask you for help you refuse to help...don't give up all your code but just the part that mimics the USART with software

30th October 2009, 05:50 AM	#20
Mr RB	I have projects on this page that sends and receives serial between a PIC 18F1320 and PC serial port, using just 2 resistors. All source code is included (in MikroC), and it uses a very simple nifty bit-bang system with the PIC timer that can be done on any PIC; Connect JuneBug to serial port and Sharp GP2 sensor