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16 bit LCD interfacing.................

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NARENDRA1234

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hi guys I am using 16 bit LCD..interfaced with PIC 18f4520..LCD is in 4 bit mode..so i want to know difference between 4 bit and 8 bit interfacing?whether is it related to maximum bits that can be transfered to LCD like suppose i am using 4 bit LCD meand it will show data upto 2Λ4 means 16 ..is it like this?
 

ckshivaram

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it is not 16 bit lcd ... it is 16X2 lcd...

lcd in 4 bit mode uses only 4 data lines and it will be connected to port pins. other 4 data lines in LCD are grounded
in 8 bit mode 8 port pins are used to connect all 8 lines of lcd data lines...

in both case Rs , r/w and en pins are required.

---------- Post added at 19:59 ---------- Previous post was at 19:57 ----------

in 4 bit youcan transfer 4 bits of data.. and 4 bits next time. so you need to shift the data to proper pins and send it.

mask the 4 LSB and send 4 MSB nibbles. the mask 4 MSB nibbles and shift data to suit the data pins of controller and send it.
 

NARENDRA1234

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it is not 16 bit lcd ... it is 16X2 lcd...

lcd in 4 bit mode uses only 4 data lines and it will be connected to port pins. other 4 data lines in LCD are grounded
in 8 bit mode 8 port pins are used to connect all 8 lines of lcd data lines...

in both case Rs , r/w and en pins are required.

---------- Post added at 19:59 ---------- Previous post was at 19:57 ----------

in 4 bit youcan transfer 4 bits of data.. and 4 bits next time. so you need to shift the data to proper pins and send it.

mask the 4 LSB and send 4 MSB nibbles. the mask 4 MSB nibbles and shift data to suit the data pins of controller and send it.

thank man so much..i just didnt get ur second passage..now suppose i want to transfer number 200 in 4 bit mode how should i transfer that?one more question..if i am using LCD in 4 bit mode means is it needed to ground remaining pins or can br floated?:-D
 

alexan_e

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The display needs 8bit instruction ,
when you use it with 4 bit interface then all the instruction are send broken in 2 nibbles (the high 4bits and then the low 4bits)
this is why this type of connection is slower but with the benefit of using less pins.

When you use the 8bit interface then a complete byte is send using all 8 lines.

The R/W (read/write) can be hardwired to ground for write only, sometimes this is useful if you want to use a lower pin count.

Alex
 

ckshivaram

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4 pins to be grounded. thats the way to transmit..... 4 nibbles at a time... so you need to shift the data appropriately to correct pins to which lcd data lines are connected.....
0x42 => 0100 0010

so this data will be masked of lower nibble and retain 0100 and send it.... next mask MSB nibble and retain 0010 . and send it

but you shift the data properly as per your hardware connections.......
 

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