Whats a complementary bit?

[secretagent]

RST IS complemnted
RS (D/I, D: Data, I: Instruction): D is NOT complemented, I IS complemented.
E is NOT complimented
etc. etc..

What does this mean? If you dont know what the bits im refering to are its from a GLCD

 

[Pommie]

Complemented means inverted and so RST should be grounded to be active and tied to the positive supply for normal operation.

Mike.

 

[secretagent]

Ok thanks another quick question... My LCD Reset is tied to the positive supply yet the screen outputs that reset is low... No matter what I do I cannot get the LCD out of reset mode! Please help...


+ your from Australlia thats awesome!!!!!!

 

[Pommie]

If it's in reset mode then how can the screen "output" anything?

Mike.

 

[secretagent]

I enable the R/W so I can read off the ports... Then I output to PORTA and have led's on it to see whats on... The LCD is off and is in RESET.... And I think the lcd is off because its stuck in reset so it never gets the command to turn on...

Thanks...

**NOTE I got another LCD through warrenty because the last one was beat up the box had a kick hole right through it and stuff! All the pins had interference and the lcd did NOTHING...

 

[Pommie]

Without a schematic and code it's impossible to even start to help.

Mike.

 

[secretagent]

Everyone... The problem was the charge pump... The screen did not come with one...

 

[jpanhalt]

Do you mean charge pump or negative supply? Which screen are you using?

John

 

[secretagent]

Chargepump for negative supply voltage... It is a NHD-12864MZ-FSW-GBW-L

It works beautifully

 

[jpanhalt]

I am using the same GLCD and assume you have seen this application note.

Source: https://www.electro-tech-online.com/custompdfs/2012/08/LCD_Contrast_Voltage_Circuits-1.pdf

Power Sequencing Considerations:

The order in which the power supplies are applied to an LCD, power sequencing, must be considered when designing an LCD bias power supply. The power sequencing requirement can be summarized by stating that the Vee (VL ) must never be present without Vdd also being present.

How do you achieve that condition at turn off using the circuit provided? I asked that question here last Winter and learned that many people just ignore that condition. I did not ignore it and went with a supply I could switch.

John