Wed 14 Feb 2007
As the laws of physics broke down and Penn State caved to inclement weather for the first time in years, I had a little bit of free time to work with the MAX3222 chips that Dallas Semi sent me. These have all of the features of the MAX232 (two TX and two RX channels) as well as shutdown and output enable. The best feature is that the chip can operate from 3.0V to 5.5V so it can be quite versatile in connecting both TTL and LVTTL devices via serial port. I ended up making a small board that has a female db9 connector and has the RX, TX and power leads for easy access. The schematics for this board are on page 12 of the datasheet (be sure to look at he 3222, not the 3232 as the power pins are different). Pin 2 of the female db9 port is connected to pin 8 of the 3222 and pin 3 of the db9 is connected to pin 9 of the 3222. Pin 5 of the db9 is grounded so no flow control is provided.
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February 18th, 2007 at 11:37 pm
[...] of the first uses for the rs232 line converter that I built last week was to access the serial port on a Linksys WAP54G that I have around. The [...]
February 20th, 2007 at 3:41 am
Man you could have put a little more work into this, why was it posted on hackedgadgets, there standards are getting low. anyone who has used USART or RS232 communication knows about the max232 chips.
February 20th, 2007 at 10:27 am
“The best feature is that the chip can operate from 3.0V to 5.5V so it can be quite versatile in connecting both TTL and LVTTL devices via serial port.”
Everyone knows about the MAX232, but this board uses the MAX3222. Often times the designers make incremental improvements to their ICs that make them more versatile and here is one example. This board is to be powered off your embedded system and will run off any logic level from 3.0V to 5.5V.
February 22nd, 2007 at 11:55 pm
[...] install the lzma and then recompile squashfs etc etc etc. The easier method is just to install a rs232 transciever on the machine and upload all of the files to another host. The memory management or [...]
February 24th, 2007 at 3:00 am
All I meant by my first post was, it would have been nicer if you were to make your project more presentable before shareing with hackedgadgets witch is a real large fanbase, I didn’t mean to be rude or anything.
heres my rs232 level converter encloser project:
http://www.ph0rkeh.com/temp/rs232_level_box/
look at _main_fullwork.jpg first it explains it all
it contains a max232 for of course serial communication, wires from there to breadboard with headers (vcc,gnd,rx,tx), there are 3 leds (2 rx/tx, 1 bi-color status), and a AVR Attiny45 microcontroller for various status on the serial line and the max232, outputs the data to the bi-color led.
I also took a shot of the max232 and max233 next to each other in there, sorry for the crappy pics, crappy camera!
February 24th, 2007 at 1:12 pm
Ph0rekh may be right, maybe I should have made the project a little prettier. The main point that I was trying to emphasize with post was that the MAX232 is somewhat obsolete and should be replaced by the MAX3222 or something like that in the hobby community. This goes along the lines of your first comment saying that anyone and everyone knows that you just put together a breadboard with a MAX232 and a few caps and you have a serial port transceiver. 5V logic levels are still dominant in the hobby and DIY community but almost every embedded consumer device runs at 3.3V logic (or sometimes lower!). It would be a waste of time to put together two different boards, so thats the novelty here. I will try to make posts that I forward to hackedgadgets a little prettier in the future.
February 24th, 2007 at 2:59 pm
Hello, everybody , maybe someone can draw or show this RS-232 to TTL level converter schematics , because i don’t understand , that schematic in that datasheet. Thanks
March 4th, 2007 at 1:43 pm
What values caps did you use?
March 4th, 2007 at 6:25 pm
I used 1uF just because I had them around. The datasheet suggest 0.1uF so those will work as well as larger caps.
March 5th, 2007 at 1:19 pm
k. Thanks!
I’d never seen this blog before I caught this project on hackedgadgets. I like it… you’re doing a great job!
btw… I like to see bare circuit boards… the sight of open, electronic magic makes me happy!
March 5th, 2007 at 6:06 pm
Thanks, I will try to keep up the work and post some circuits.
March 17th, 2007 at 10:41 am
Dear Sir:
Can I use usb-rs232 cable to access FON console? Does it differ from TTL to RS232 converter ?
Thanks
March 17th, 2007 at 11:18 am
Jengr,
I don’t know which usb-rs232 cable you are using, but I am guessing that it connects to a USB port on your machine and provides a rs-232 output. You still need to convert the rs-232 level signal to a LVTTL (3.3V) signal, so you still need a level converter, such as the MAX3222 above. Hope this helps.
October 18th, 2007 at 7:44 am
[...] max232 (TTL) adapter [...]
October 29th, 2008 at 3:40 am
A similar guide can be found here: http://www.panic1.be/tag/level-converter/