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PIC/633 UART question


New member
For you folks interfacing LCD's to Microchip PICs, are you connecting directly to the UART module with the LCD configured for standard RS-232, are you using a TTL-RS232 converter or are you configuring the LCD for logic level?

I am using a dspic30F4011.
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CF Tech

The CFA-631, CFA-632, CFA-633, CFA-634 and CFA-635 can all be configured for "inverted logic level RS-232", which means they can be connected directly to the UART pin of a microcontroller. You can use the special instructions when ordering to specify it, or write support and they will issue a semi-custom part number.

If you need a longer cable between boxes, it would probably be better to use "real RS-232", but if the micro and display are close together and in the same box the logic level should work fine.


New member
Good info, thx!

To check my comprehension I will summarize:

-The PIC has logic-level at the UART pins and the LCD needs to be configured accordingly.

-To use "true" RS-232 a converter needs to be used at the UART pins to convert the signal and the LCD can then be "regular configuration" RS-232.


Also, if mine is configured for regular RS-232 (jumpers 2, 4, 6), how do I configure for inverted logic?
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CF Tech

Yes, I think you have it.

(Assuming you have a CFA-633 . . .) To convert the module to logic level, it takes a bit of work. You basically take off U4 and close two jumpers that are under it. I think there are also some caps that can come off, but they are not really important.

If you want to convert it on your side, please write support@crystalfontz.com and they can get you a document that shows how to do the conversion to logic level.