might of fried my Parallax serial 4*20 LCD
rhubarb
Posts: 2
Hi
In my haste, I connected my new serial LCD to the RS232 port of a Zilog Z8 Encore dev board. All I got was garbage on the LCD. I have twiddled every parameter in the test program I can think of but no success.
I am aware that the baud settings must match on board and LCD.
I am wondering if the LCD can handle RS232 voltage levels. If not, then is the LCD fried? It would seem so because after correctly? connecting the LCD to the 2nd UART (TTL levels) I get nothing (except the cursor top left)
If I have fried something then maybe it is only the serial interface on the LCD. Can I resurect it by going parallel instead? Is there a datasheet for this?
Peter
In my haste, I connected my new serial LCD to the RS232 port of a Zilog Z8 Encore dev board. All I got was garbage on the LCD. I have twiddled every parameter in the test program I can think of but no success.
I am aware that the baud settings must match on board and LCD.
I am wondering if the LCD can handle RS232 voltage levels. If not, then is the LCD fried? It would seem so because after correctly? connecting the LCD to the 2nd UART (TTL levels) I get nothing (except the cursor top left)
If I have fried something then maybe it is only the serial interface on the LCD. Can I resurect it by going parallel instead? Is there a datasheet for this?
Peter
Comments
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·· The input cannot handle RS-232 levels, but it would be difficult to tell if you damaged the unit without testing it.· If you have a MAX232 or similar Line Driver you could use that to get the levels where they should be.· The other reason you would get garbage is that typically RS-232 levels serial is inverted, while the Serial LCD uses non-inverted TTL level serial.· I hope this helps.· Take care.
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Chris Savage
Parallax Tech Support
If I have fried the serial part of the LCD can I use it as a parallal with a Hitachi HD44780 interface?
Peter
I have the interface done, (picture is running a loop to output alphabet) I just have to finish the serial input interface. I plan to code the other pins to respond to serial commands to be used as additional external pins as well as enable the ADC's for serial communication, heck as long as I am using a crystal or oscillator I may as well throw a 24 hour clock routine to set and read time and while I am at it throw in some PWM access hooks as well.
I could send you one to test if you like, I have quite a few mega48's just sitting in tubes.
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Think outside the BOX!
Post Edited (metron9) : 10/29/2006 6:41:50 PM GMT
·· If the interface isn’t damaged, it should work with the 3.3V interface, although I would recommend a 1K resistor to be used in between the 3.3V pin and the LCD Serial input.· Take care.
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Chris Savage
Parallax Tech Support