I'd bet the multiple names are for two things (1) consistency with
datasheet (2) shorthand/abbreviation. It often is quite useful to make
names a short as possible. However, abbreviations may not be
consistent with the datasheet and may lead to ambiguity; hence the
"proper" full length names (TRISAbits.TRISA0) are used in conjunction
with the short ones (TRISAbits.RA0)

On Mon, Apr 20, 2015 at 1:59 PM, Nathan House <nathanpiclist@gmail.com> wro=
te:
> Hi,
>
> The main.pre file in my MPLAB X project seems to show the definitions for
> the configuration registers. One example is this:
>
> typedef union {
> struct {
> unsigned TRISA0 :1;
> unsigned TRISA1 :1;
> unsigned TRISA2 :1;
> unsigned TRISA3 :1;
> unsigned TRISA4 :1;
> unsigned TRISA5 :1;
> unsigned TRISA6 :1;
> unsigned TRISA7 :1;
> };
> struct {
> unsigned RA0 :1;
> unsigned RA1 :1;
> unsigned RA2 :1;
> unsigned RA3 :1;
> unsigned RA4 :1;
> unsigned RA5 :1;
> unsigned RA6 :1;
> unsigned RA7 :1;
> };
> } TRISAbits_t;
> extern volatile TRISAbits_t TRISAbits @ 0xF92;
>
> What is the point of making the same bits accessible through more than on=
e
> name?
>
> I.e. the following lines of code are identical, correct?
>
> TRISAbits.RA0 =3D 1;
> TRISAbits.TRISA0 =3D 1;
>
> The LATAbits definition is even more convoluted:
>
> typedef union {
> struct {
> unsigned LATA0 :1;
> unsigned LATA1 :1;
> unsigned LATA2 :1;
> unsigned LATA3 :1;
> unsigned LATA4 :1;
> unsigned LATA5 :1;
> unsigned LATA6 :1;
> unsigned LATA7 :1;
> };
> struct {
> unsigned LA0 :1;
> };
> struct {
> unsigned :1;
> unsigned LA1 :1;
> };
> struct {
> unsigned :2;
> unsigned LA2 :1;
> };
> struct {
> unsigned :3;
> unsigned LA3 :1;
> };
> struct {
> unsigned :4;
> unsigned LA4 :1;
> };
> struct {
> unsigned :5;
> unsigned LA5 :1;
> };
> struct {
> unsigned :6;
> unsigned LA6 :1;
> };
> struct {
> unsigned :7;
> unsigned LA7 :1;
> };
> } LATAbits_t;
> extern volatile LATAbits_t LATAbits @ 0xF89;
>
> I don't know why they union'd a separate struct for each of the bits
> instead of putting them all in one struct like with TRISAbits, but the sa=
me
> question applies to this as well.
>
> What's the point of all that redundancy?
>
> Thanks,
>
> Nate
>
> -----
>
> I'm a college student, take it easy on me ;-)
>
> Check out my small hobby electronics business!
> www.foxytronics.com
> --
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