ST7Flite29 and LCD

m_kasravi2002 · ‎2006-02-14

Posted on February 15, 2006 at 05:13

ST7Flite29 and LCD

m_kasravi2002 · ‎2006-02-12

Posted on February 13, 2006 at 01:37

I have written a piece of code for ST7Flite29 to display some data in a LCD module, but nothing is displayed yet. I have checked the hardware .LCD is connected to the port A. VDD and VSS of both micro and LCD is present. Micro oscillator is running perfectly.

I use Cosmic Compiler then I program the micro with the created .S19 file via Flash Bash programmer. The program algorithm is very simple. At first LCD will be initialized, and then some data will be written to PADR to be displayed on LCD.

I was wondered if someone has a same experience for more discussion and help.

Best Regards,

fggnrc · ‎2006-02-12

Posted on February 13, 2006 at 08:06

Pls, check the contrast voltage.

If it is too low, the content of your display could be ok, but you can't see it.

Search for ''LCD'' in this forum too, you will find some useful code.

Regards

EtaPhi

m_kasravi2002 · ‎2006-02-13

Posted on February 14, 2006 at 01:33

There is no command for contrast voltage for LCD module I am working with.I will search the forum,thank you anyway.

m_kasravi2002 · ‎2006-02-13

Posted on February 14, 2006 at 01:36

There is no cammand for contrast voltage in LCD module datasheet,I will search the forum,thank you anyway.

Regards,

fggnrc · ‎2006-02-13

Posted on February 14, 2006 at 03:45

The contrast I mean, is the bias voltage that is feeded to the LCD module.

A trimmer sometimes provides this bias.

Another option is a temperature compensated voltage reference made of a LM335, some resistors and a op-amp like LM307.

EtaPhi

m_kasravi2002 · ‎2006-02-14

Posted on February 15, 2006 at 05:13

yes,the contrast voltage is fixed via transistors,LCD module works properly in another application with st7324.

the LCD driver is HT1621.

I think the micro is not running the program.I am using a 16MHz external crystal oscillator.but there is another internal RC oscillator.Do you think option byte settings may cause this problem? how does internal RC oscillator affect fosc?

Regards,

Mary