lcd query

sjo · ‎2004-02-10

Posted on February 10, 2004 at 10:44

lcd query

sjo · ‎2011-05-17

Posted on May 17, 2011 at 11:58

I notice in your examples for the DK3200 PortA (peripheral mode) is used for lcd data.

In the past I have used P0 (address/data) for lcd data - this method was also used on the DK900 dev boards - is this possible with the uPSD.

I cannot see any reason why not but thought I would check here before I try it. This would then free PortA for GPIO.

Many Thanks

sjo

joseph2399 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

According to page 47 of the uPSD 323x data sheet,

(http://www.st.com/stonline/books/pdf/docs/9188.pdf), Port 0 and Port 2 are dedicated external address and data bus and can NOT be used as GP I/O or Peripheral I/O mode.

sjo · ‎2011-05-17

Posted on May 17, 2011 at 11:58

I know they are dedicated, as they are on all 8051 with external memory.

My question is can a upsd be attached to an lcd on p0 as the DK900 kit was.

I have attached schematic of what I mean.

Regards

sjo

sjo · ‎2011-05-17

Posted on May 17, 2011 at 11:58

As I said before attaching an lcd to P0 is quite common on the 8051 world so I thought I would try it anyway.

I have done this on the DK900 kit with an 8031 attached.

It can be done and works very well. I have attached the code so everyone else can use a lcd on P0, thus saving a port.

The only improvements is to use either PA or PB (bits 0,1) for the RS and RW lines , this would save having to use the cpld.

Simply write 0x03 to the CONTROL register (address out) and set the DIRECTION as output - this can be done at runtime.

Regards

sjo