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Communicating with an LCD

 
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Communicating with an LCD
PostPosted: Mon Feb 22, 2010 6:15 pm     Reply with quote

My pic does not allow I2C or SPI communication, and it doesn't list anything else for communication either. What kind of LCD can I use with a pic that has no communication features? Does CCS allow me to use software based I2C communication?
dyeatman



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PostPosted: Mon Feb 22, 2010 7:19 pm     Reply with quote

What model of PIC do you have that has no comms hardware at all?
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Rohit de Sa



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PostPosted: Tue Feb 23, 2010 1:24 am     Reply with quote

dyeatman wrote:
What model of PIC do you have that has no comms hardware at all
It could be one of the baseline PICs. But, yeah, you should always post your processor so that others on the forum know what you're working with. It's just one of those things that'll get you help faster. Very Happy

Quote:
Does CCS allow me to use software based I2C communication?
Yes it does. Go through the manual. You can even use a software UART.
Code:
#use spi
#use i2c
#use rs232


Rohit
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PostPosted: Tue Feb 23, 2010 1:55 am     Reply with quote

it's a pretty common mcu, 16f684.

I tried using software i2c but I can't get it to display anything. When I use the following code, it says the identifiers are unidentified.

#use i2c(slave,sda=pin_c3,scl=pin_c4)

? it's something like that, but I don't have it in front of me. Then later in my code I use:

void i2cstart()
{
scl=1;
sda=1;
sda=0;
scl=1;
}

Do I need to add:

int1 sda;
int1 scl;

???
PCM programmer



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PostPosted: Tue Feb 23, 2010 2:04 am     Reply with quote

Quote:

What kind of LCD can I use with a pic that has no communication features?

Use a standard 16x2 character LCD with an HD44780-compatible parallel
interface. This requires 6 or 7 general purpose I/O pins on the PIC.
No special communications module is needed. These LCDs are available
from most electronics parts suppliers. Example:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=67-1780-ND

Then use this software driver with your PIC to display characters on the LCD:
http://www.ccsinfo.com/forum/viewtopic.php?t=24661

More information:
http://www.geocities.com/dinceraydin/lcd/intro.htm
You don't really need most of the information on that page.
All you need is the driver in the link above.
Rohit de Sa



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PostPosted: Tue Feb 23, 2010 3:18 am     Reply with quote

What sort of LCD do you have? A simple character LCD? Some character LCDs have a serial 'backpack' on them. This allows them to communicate using I2C, async-serial, SPI, and other serial protocols.

In case your LCD is a plain-jane character LCD, use PCM's link to get it to work.

Rohit
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