Reg: LCD problem

[evaradharaj]

Hi,

I am using pic16f72 with 4 MHz crystal and 16x2 LCD display. The Interfacing wire between LCD and to the controller is about 30cm long. I am using lcd.c driver file. I have 2 loads which is driven by BT136. The load is two electronics choke with lights (around 80 watt each).

The program is to switch on the lights alternatively (LOAD 1 ON/LOAD2 OFF & LOAD2 ON/ LOAD1 OFF for mentioned period). My program is working properly SOMETIMES. But sometimes, it is not working properly. For example load1 is not switching off when load 2 ON. The LCD is displaying some strange characters...

I am driving the TRIACs by using MOC3021. Why this problem is happening ?please give me suggestion to correct the problem.

If it is EMI/RF problem, how it will come to the circuit? By LCD wires or by the TRIAC circuits (I have not included the snubber circuit).

Thanks
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embedding innovation in engineers

[Gabriel]

to rule out code/logic errors we would need to see the code.
if you have a Circuit diagram you could maybe post that too.

you could have power problems... maybe your pic is reseting or something..

i think you havent provided enough information for us to help you...

do you have Zero crossing detectors....
is there dimming involved or just plain ON/OFF?



Lastly: BE VERY CAREFULL WHEN PLAYING WITH MAINS VOLTAGE-

G.
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CCS PCM 5.078 & CCS PCH 5.093

[Mike Walne]

We need loads more information, schematic, basic coding etc.

How are you driving the MOC parts?

Mike

[PCM programmer]

Do some basic trouble-shooting by reducing the extreme conditions.
Example: Remove the 80 watt loads and replace them with LEDs.
Does the problem go away ? If so, investigate that circuit with an
oscilloscope and closely examine your circuit connection methods
and power supply. Also, shorten the LCD leads to only 3 cm.
Does the problem the problem go away ? If so, again, look closely
at your power supply and wiring design.

[varadharaj]

Hi,

I changed the ribbon wire for LCD with microcontroller and added a snubber circuit of 150ohm and 0.01uf capacitor. The whole module is working fine.

But when we switch on the motor from nearby switch, The LCD is corrupting and also the light load with electronic choke is not turning off...
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Embedding Innovation

[Mike Walne]

Work on the premiss, prevention is better than cure.

Try snubbing the switch, (i.e. deal with the problem at source).
Otherwise you either have to find out how EMI is getting into the PIC or apply ALL the cures to the PIC.

Is the PIC still running after you switch motor on?

Mike