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Messages - Andrew_B

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Character LCDs / Re: NHD-0216K3Z-FL-GBW-V3 outputting 5V on data pin
« on: December 06, 2016, 05:17:02 PM »

I replaced my 3.3V MPU with a 5V MPU and it solved my problems. There was nothing wrong with either LCD. I just overlooked the fact that the LCD required 5V logic. This would have been one of the first things I checked had the LCD not worked at all, but as I said, it was initially able to transmit the data with 3.3 V. Lesson learned: always read the datasheet thoroughly :) Thanks again for your help.

Character LCDs / Re: NHD-0216K3Z-FL-GBW-V3 outputting 5V on data pin
« on: December 05, 2016, 02:10:32 PM »
Hi Paul, thanks for the response. R1 and R2 are open, and the baud rate for the program is 9600. I was able to get the LCD to display characters correctly on a breadboard, but my problems started after soldering the parts to a protoboard. Here's my schematic: Pin 3 of the LCD is supplied by a 5V Linear Regulator (U2 on the schematic), pin 2 is grounded, and pin 1 is connected to pin 3 of the PIC12 (U5).

I overlooked the fact that the RS232 signal should be 5V compatible. The PIC12 that I am using has 3.3 V logic levels. So that may be the problem. Still, the data communication worked earlier with the 3.3 V signal.

I ordered another LCD (the same one) and replaced my initial LCD, and I replaced my PIC12, but my programmer is still not detecting the PIC12. So, I will explore the possibility of wrong connections between the programmer and LCD. I should also note that the new LCD is outputting around 5V on the data input port (pin 1) as it was with my initial LCD, and I still don't know if this is a problem or not. Shouldn't this voltage be resting at zero if there is no connection to the PIC12?

Character LCDs / NHD-0216K3Z-FL-GBW-V3 outputting 5V on data pin
« on: December 04, 2016, 04:04:55 PM »

I am using a NHD-0216K3Z-FL-GBW-V3 Serial LCD Module configured for RS-232 communication. Datasheet:

I have successfully transmitted data to the LCD using a PIC12 MPU (3.3V logic) on a breadboard. However, after soldering the components onto a protoboard, I discovered that my MPU was not functional and my LCD was outputting ~5V on its RS-232 serial data line (pin 1). There is no external connection between the data pin and the supply pin, so I suspect that there is an internal short-circuit that happened during soldering.

I have not been able to test the data communication because I have no extra PIC12s, but I'm willing to bet that a new PIC12 will break once it's connected to the 5V coming out of the LCD data pin.

So now I am trying to decide if I need to order a new LCD in addition to a new PIC12. Is there any reason, other than it being broken, that the LCD would output 5V on its data input pin? Thank you.

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