LCD : unused positions are are weird characters

[SneaKSz]

Hello all,

I'm using the "LCD-Type BATRON BTHQ 21605AV-YETF-LED04-I2C-5V " ,
datasheet : https://www.electro-tech-online.com/custompdfs/2011/02/312175.pdf.

I'm able to get ABCDE on the LCD like I want to , but all the other used characters of the first row and all the chars on the second row are 'arrows'.

I cleaned the screen and then send the "ABCDE" and stopped , but once again all the other chars are " arrows" .

Someone has an idea? This cant be hard.


write data :

	SendStart();
	SSPBUF= 0x76;// i2c slave Address 
	SSPFlag();
	SSPBUF= 0x00;// Control byte for Instruction 
	SSPFlag();
	SSPBUF= 0x01;// clear screen
	SendStop();
	SSPBUF= 0x80;// DDRAM Address set to 00hex 
	SendStop();


	SendStart();
	SSPBUF= 0x76;
	SSPFlag();
	SSPBUF= 0x40;// Control byte for Data 
	SSPFlag();
	SSPBUF= 0xC1; // A
	SSPFlag();
	SSPBUF= 0xC2; //B
	SSPFlag();
	SSPBUF= 0xC3;//C
	SSPFlag();
	SSPBUF= 0xC4;//D
	SSPFlag();

Kind regars

 

[Mr RB]

You didn't send a SendStop() ??

Logical deduction would be that either you are filling the screen with arrow chars before you send the ABCD (like a problem with clear screen command) OR you are continuing to send arrow characters after you send ABCD.

 

[SneaKSz]

hi,

its the second option you've said.

Ive forgot the SendStop(); indeed !

Ill try it out now .

Thanks Mr RB !!

 

[SneaKSz]

Hmm Still does not work, the arrows are still present.

        SendByteControl(0x76,0x00,0x34,0x0E, 0x06); // command

       SendStart();
	SSPBUF= 0x76;
	SSPFlag();
	SSPBUF= 0x40;// Control byte for Data 
	SSPFlag();
	SSPBUF= 0xC1; // A
	SSPFlag();
	SSPBUF= 0xC4; // A
	SSPFlag();
	SendStop();

send :

void SendByteControl(unsigned char  address ,unsigned char controlb,unsigned char fs,unsigned char  display, unsigned char entry  ){
SendStart();
SSPBUF= address;
SSPFlag();
SSPBUF= controlb;
SSPFlag();
SSPBUF= fs;
SSPFlag();
SSPBUF= display;
SSPFlag();
SSPBUF= entry;
SSPFlag();
SSPBUF= 0x35;// extended
SSPFlag();
SSPBUF= 0x04;
SSPFlag();
SSPBUF= 0x10;
SSPFlag();
SSPBUF= 0x42;
SSPFlag();
SSPBUF= 0x9F;
SSPFlag();
SSPBUF= 0x34;//Regular
SSPFlag();
SSPBUF= 0x80;
SSPFlag();
SSPBUF= 0x02;
SSPFlag();
SSPBUF= 0x01;
SSPFlag();
}

 

[SneaKSz]

Clearing the screen via a command didnt work , I had to clear them manually. Ive written a blank spot to every position on the display.

Kind regards!

 

[Mr RB]

Check the datasheet for the clear screen command, many of the graphics LCDs clear the screen TO a selected character.

If your LCD works like that it may explain what was happening.