How to use the DATA pins (EMI) to interface LCD and printer!!!

[sany_as]

Posted on January 04, 2007 at 13:41

How to use the DATA pins (EMI) to interface LCD and printer!!!

[sany_as]

Posted on December 14, 2006 at 08:09

Dear Sir,

I am planning to interface a graphical LCD (128X64) and a thermal printer to STR710Fz2T6.

Is it possible to use the lower data pins of the EMI bus (D0-D7) for this purpose.I am planning to use two select pins i.e. CS0 and Buffer_en pins to toggle between these twp peripherals.

CS0 Buffer_en (chip select)

1 1 -----> 1 (RAM)

0 1 -----> 0 (LCD)

1 0 -----> 0 (Printer)

Is this a possible way.

Kindly mention the constraints of using the EMI interface . Also the Address and Data pins.

It would be grately helpful if you can please help me figure out this design problem.

Looking forward to your reply in anticipation

Regards and thanks in advance

Sany

[davidbellegarde9]

Posted on December 19, 2006 at 05:46

Hello,

This solution should not work because when the CS signal is not asserted, the data bus will be Hi-Z.

If you use other signals than EMI ones to drive the LCD, maybe it could work.

Another problem is the EMI signals are clocked by MCLK but what about buffer_en? The system will be synchronous with which clock?

Regards,

Dave.

[sany_as]

Posted on December 22, 2006 at 02:10

Thanks for the response.

We are planning to keep the RAM selected by default. i.e keeing th eCS0 and Buffer en pin always 1 and then to switch to LCD or Printer(thermal) using the single bit.

What is the problem with Hi-Z

For control signals of LCD i am using the GPIO pins while for data signals for LCD and strobes for the printer i am using the Data bus of STR..

Is this a feasible design?

Kindly suggest!!!

Regards

Sany.

[davidbellegarde9]

Posted on January 04, 2007 at 13:41

Hello,

If I understand well, 3 kind of devices will share the EMI data bus which are RAM, printer and LCD. And you will select these devices by using nCS0 and buffer_en signals. The same EMI bank for the devices.

A simplest way is to use the other nCSx signals, I mean the other EMI banks.

It will be difficult to synchronise the LCD access because the GPIOs and EMI don't use the same clock domain.

By using correctly the address bus, I mean each devices at different addresses. I understand how it should work.

The remaining problem is to have the right timing for the different chip. How could you solve this?

Regards,

Dave.