4 Bit Lcd Hookup

[GEEZER]

Thanks Edward, the LCD must operate whether the serial DAC is operating or not. My LCD and my serial operated DAC must be totally autonomous.

I saw a post recently where a guy was running three serial ports out of one chip, so I am sure there is some way to run the LCD and still have one serial output.

Steve, correct me if I'm wrong. The shift out command looks to be a one bite at a time affair with a lot of code.

I could get a parallel operated DAC, but wouldn't I still need a clocking pin?

Your suggestions are greatly appreciated.

The Geezer

[mister_e]

wich DAC you want to use? If i can suggest one simple MAX517 wich work with the I2C bus. Yeah ok, only 8 bit of definition but, how much precision do you need?

[GEEZER]

The DAC is an adXXXXX, can't rember the exact number. It's a quad with 255 steps per channel. 8 data bits and 2 bits to select channel. It requires an SPI output, an sdo, a clock pin and a ground, I believe. These are available on portC.

I think I can work that all out, but I need to move the LCD from portc, where it is working fine, to leave those aformentioned portc pins for the DAC.

I am not asking someone to write my code, I am willing to do the work. To make my question more clear:

I understand that pins 7,6,5, & 4, on portb will transfer the data or commands in two 4 bit parts. I understand that the RS signal will tell the LCD chip whether the transfered data is a command such as clear-screen, or data to be displayed such as "Hello".

I am ASSUMING that the E_BIT is a timing pin which drives the whole shbang much like an oscillatior.

I am ASSUMING that the LCDOUT command is not just a word, but a binary routine, ( when compiled) that controls these involved pins, and in a timed sequence send commands followed by data to control the Hitachi chip and make it do what my basic program code tells it.

I can use a clko pin from portc and make all this work. But I need another pin for this function, because I need the portc hardware to run my SPI DAC.

Does this make sense? I am confident there is some quite simple way to do it. My novice status (read ignorance), is my drawback. If you can help me with an understanding of theory, I know I can work it out.

You will notice In the above paragraphs I use the word "understand", (read "think I understand"), and "ASSUMING" which best describes the user of the word with the first 3 letters of the word.

Any assistance is greatly appreciated.

The Geezer

[GEEZER]

Thanks everyone. I am running on portb now, with EBIT and RS on portc. Have pins left on C for my serial hookup DAC.

Thanks much,

The Geezer

P.S. And as Arnold says, "I'll be back".