STM32F4xx Discovery parallel interface to ST7920 LCD 8 Bit

Rahul Kumar · ‎2017-03-06

Posted on March 07, 2017 at 02:38

Hi All,

I am trying to interface my STM32f4xx Discovery Board to ST7920 LCD using 8-Parallel Mode. Well I have tried a lot . But the LCD does not display any character. I have followed all the exact initialization procedure for the LCD as per the LCD datasheet. After initialization I just want to desplay hello world on the LCD. But itdoes not work at all . If any one can help. I am attaching the LCD datasheet. Here the code I have made.. . The code compiles and I am even able read the data from the DDRAM and CGRAM of the LCD. But I ma unable to display any data on LCD.

#st7920 #st7920-lcd

S.Ma · ‎2017-03-07

Posted on March 07, 2017 at 20:39

This seems tricky. The spec is probably the display controller (chip on glass). You would need also a display specification. If this is LCD, the controller needs to generate higher voltages with charge pumps using application capacitors. There should be a connector or flex ribbon specification, a display module specification.

Then, to test the display use SW GPIO toggling to get the display up and running.

Tesla DeLorean · ‎2017-03-07

Posted on March 07, 2017 at 20:53

Not looking to wade into this.

You should probably document/diagram the connectivity, and verify none of your pin selections clash with on-board hardware.

Incomplete code (non-compilable), on hardware configurations no one else is using, isn't going to get many eyes looking at it.

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

jasonforest9 · ‎2017-06-21

Posted on June 21, 2017 at 21:31

Rahul, I would like to know if you had any success with this dev kit and your display?

Rahul Kumar · ‎2017-07-01

Posted on July 02, 2017 at 01:56

Yes I was able to solve the issue of display . I had to manage my timings ( delay ).

A3 · ‎2019-02-21

Hi @Community member

can you share the display driver code.

AvaTar · ‎2019-02-21

The OP's answer is a bit terse.

LCD displays use internal step-up converters to supply the screen, wich have startup times of dozen or hundreds of milliseconds. With a significant temperature dependency on top of that.

Check the datasheet, and add some contingency reserve for your delays.