Logic behiand sending 4bit data to a 16X2 LCD.

[Qaisar Azeemi]

HI All;

can you please explain me the Logic /Idea behiand sending 4 bit data to 16X2 LCD module as it is operated with 8bit data pins? i am confused how will the LCD respond when it detects the missed nibble? or it will display wrong values or get wrong commands as it is getting 4 bit data instead of 8bit data?

Thank you

 

[ericgibbs]

HI All;

can you please explain me the Logic /Idea behiand sending 4 bit data to 16X2 LCD module as it is operated with 8bit data pins? i am confused how will the LCD respond when it detects the missed nibble? or it will display wrong values or get wrong commands as it is getting 4 bit data instead of 8bit data?

Thank you

hi,
During the LCD initialization sequence, you send a FUNCTION set Command Instruction to the LCD controller which prepares it for 4Bit operation.
[refer HD44780 LCD datasheet]

After that command you send Commands and Data as 4 Bit Nibbles. Each nibble is sent using the Enable pulse sequence.
If BUSY is used, the program waits until the LCD is not Busy and then sends the next nibble.

The High 4 bit lines of the LCD are used, D4 thru D7, High nibble first, then Low nibble.

 

[alec_t]

The idea behind sending 4-bit data is to enable micros with only 4 available output pins to be used, or to free up pins for other uses.

 

[Qaisar Azeemi]

CAN you please tell me about command that is sent to instruct the LCD that it should use only four bit data? and should only upper nibble of LCD is used for that purpose?
i am using JHD 164A LCD Module.

 

[Nigel Goodwin]

CAN you please tell me about command that is sent to instruct the LCD that it should use only four bit data? and should only upper nibble of LCD is used for that purpose?

Why don't you just read the datasheet?.

Or consult my PIC tutorial on LCD's for that matter?.

The command is 'Function set' with a specific bit cleared.

 

[ericgibbs]

CAN you please tell me about command that is sent to instruct the LCD that it should use only four bit data? and should only upper nibble of LCD is used for that purpose?
i am using JHD 164A LCD Module.

hi,
Look at this clip from the data manual.