Hi - unfortunately I don't think this is possible in CCS, and probably 
not in other PIC C compilers, but that's just a guess.

What you're trying to do is something like this:

typedef union {
   byte Byte;
   struct {
word  SCME        :1;    /* Self-clock mode enable */
word  PCE         :1;    /* COP Enable during Pseudo Stop Bit */
word  PRE         :1;    /* RTI Enable during Pseudo Stop Bit */
word              :1;
word  ACQ         :1;    /* Acquisition */
word  AUTO        :1;    /* Automatic Bandwidth Control */
word  PLLON       :1;    /* Phase Lck Loop On */
word  CME         :1;    /* Crystal Monitor Enable */
   } Bits;
} PLLCTLSTR;

(this is from a header file for the freescale MC9S12NE64)

so that in code you can say:
PLLCTLSTR foobar;	(with some compiler-dependent pragma to set foobar to 
the correct special chip register)

then:
foobar= 0xFF;
or
foobar.PRE= 1;
etc.

but for splitting across two 8-bit registers, the union{} would have to 
cover both, and any assignment directly (like foobar= 0x0123) would set 
all the pins on both ports.

Even if this is possible in other compilers, they are going to generate 
a number of masks and shifts and so forth, so it won't be smaller/faster 
than how you'd do it "by hand".

So I think you're going to have to write a function to do writes to your 
LCD.  See bit_set() and bit_clear() CCS functions to efficiently 
set/clear a single bit.  Alternatively something like:
PORTA= (PORTA & 0x7) | ((LCDdata & 0b0111000) >> 5);
would set the lowest 3 bits of PORTA to bits 6,5,4 of LCDdata.

Also see #inline, you may want your function inlined for speed.

This low-level bit-bangyness takes up a remarkable fraction of the code 
for many of my projects.  It isn't always possible to arrange the 
hardware pin layouts to make the software simpler, as I guess you've 
discovered as well.  :)

J




moja nona wrote:

> Hello.
> 
> Situation:    Driving a LCD. 3 pins are say on PORTA, 4 pins are on
> PORTB. I am using CCS for programing. Is there a way to group the
> pins of both the ports into a single register? The code would be
> easyer/prettyer.
> 
> Regards!
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