Tagged Questions

5
votes
1answer
132 views

How to connect RS232 (“Opto-RS232”)

--Background-- I'm setting up a pretty standard RS232 interface from a digital caliper to a microcontroller, via a MAX232 chip (or in my case, MAX3222, which is the 3.3V-supply variant with 2 ...
4
votes
1answer
188 views

Why MAX232 works without any capacitors?

I was playing today with a very simple setup of pic16f876 and max232 connected to the COM port of a PC running a terminal emulator. I was just testing (the uc simply echoes anything it receives) when ...
0
votes
2answers
402 views

Arduino serial communication with printer

I'm working on a project with an Arduino Mega 2560. I connected the board to a MAX232CPE in order to communicate in serial mode with a thermal printer. I connected the MAX232 to one of the 3 extra ...
1
vote
2answers
2k views

PIC18F + MAX232 USART Bizarreness

Okay, I've been struggling with this for weeks, and it's blowing my mind. I have been working with PICs for a long time, and I'm very confused as to why I can't make my USART work. First off, a few ...
1
vote
1answer
151 views

RS-232 Zero (-7V) drops when I connect db9 connectors

I'm interfacing with a system using RS-232. To communicate, I use MAX2322 for TTL <-> RS-232 to interface with PIC microcontroller and PL2303 for USB <-> RS-232 to interface with PC. All of the ...
3
votes
4answers
2k views

Can I use 10\$\mu\$F caps in a MAX232?

this is just a quick and dirty question. I don't understand the purpose of the 1 \$\mu\$F caps in the MAX232 circuit. What do they do, exactly? Can they be skipped? Can they be swapped with 10 ...
4
votes
4answers
2k views

Do I have to use a MAX232 chip?

I am trying to interface my ATmega chips to the computer using a serial interface. I have read that this can be done directly by connecting the appropriate pin between the chips and the serial pin. ...