Programming Changes Needed for CFAH1602B-TMI-JT

[BME Design Team]

Hello,

My senior design team is trying to use a PIC16F874 microcontroller to display measured force values onto a CFAH1602B-TMI-JT LCD screen. The program we have currently written for our application does not show anything on the screen at all (not even the blinking cursor). We have an example program which simply displays the text "Hello" which does work on the Quick Start Education Board's LCD screen. However, when we remove the chip from the board and place it in our protoboard along with the CFAH1602B-TMI-JT, nothing is displayed.

We believe that we need to make changes to our code to accommodate for the CFAH1602B-TMI-JT. The program which displays on the Quick Start Board does not have R/W output. Is it necessary for the CFAH1602B-TMI-JT to have an R/W connection to display? My team and I are stumped on this problem. Any help would be greatly appreciated.

Thank you,

BME Design Team

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[cosmicvoid]

It is not necessary to have R/W connected to the cpu; you could operate in write-only mode by leaving the R/W input grounded. But then you would have to use delays between each write, to allow for the execution time of each command.

Its really more efficient to use the R/W signal, so that you can read the busy status of the display.

If you want help with the code, then you should attach the source file for us to look at. Also, do you have anyway to vary the input for Vo, to adjust the contrast? You should be able to see a change in darkness when you take the Vo voltage near to ground.

 

[CF Tech]

Make sure Pin 3 (Vo) is set properly. Typically it should be at 0.5v to 1.0 v for starters.