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Post by huckle on May 19, 2007 11:30:04 GMT -5
I made a max233 rs232 card with the schematic on your page. I couldn't get it to work reliably until I followed the instructions on the max233 datasheet however (figure 11). This shows to connect pins: 12-17, 11-15 and 10-16 together. Without doing this I found that it would not always transmit data.
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Post by gmoon on May 19, 2007 14:55:49 GMT -5
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Post by Doppleganger on May 25, 2007 23:42:47 GMT -5
I'm a big fan of having a fully functional rs232 interface. All the control lines present. I guess if you're only at 1200bps, then it's not a big deal... But, I'm always calling bbs's at 9600, or 38400bps. The C= really can't scroll the screen fast enough to keep up with either of them, so RTS/CTS has to be enabled so you don't get garbled text.
I have one of those Brother printer interfaces... well, a couple of them. Haven't really tried using it yet, though I noticed that it's just a simple TX/RX/Ground kinda setup...
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moparram
Junior Member
Sterling Marlin-Nascar legend
Posts: 58
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Post by moparram on Dec 2, 2007 21:41:13 GMT -5
I'm trying to be slick and make a pc board with the MAX233 interface in Jeff Ledger's "Putting the Commodore Online". An old HesModem case and connector will be used. I made a layout on ExpressPCB, and hope to make a transfer onto one of those Radio Shack kits. This is probably overkill. Jeff, you show pin 7 of the Max233 connecting to pin 2 on the Commodore User Port, is this correct? I have a preliminary layout, but it's a .pcb file I could email to you. I've also read other members modifying the original schematic. Actually I know nothing about what I'm trying to attempt, but I figure this would be a rather simple project to try.
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Post by Jeff Ledger on Dec 3, 2007 11:17:43 GMT -5
In reviewing the document and the userport spec, it looks like an error. According to the "Commodore Reference Guide" PIN 2 is +5v while PIN 1 is GND.. (check me) Also, it *might* be a good idea to consider some caps near the MAX233, although I never had issues with this. Here's the reasoning being it... UART and Serial Communication (Note the paragraph about "Chargepumps" below the picture) I've been a little MIA from the Commodore community this last year in a self-study of electronics and microcontrollers (namely the Propeller) so I've gained a little knowledge since I published that document. After I finish the PETSCII.com renovations, I'll be doing some serious testing/editing of that schematic as well. Jeff
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moparram
Junior Member
Sterling Marlin-Nascar legend
Posts: 58
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Post by moparram on Dec 3, 2007 20:51:06 GMT -5
Maybe I should wait for the updated version to put it on a PCB! ;D
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