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I use a Cypress Fx2. It's no problem to write a value to dcf.sekunde but if i set dcf.minute to 0 or such a other value, the controller will stops/crash.
I'm not sure if the struct definition is correct or if i must reserver a address block for it. i hope someone can help me.
Thanks
Sorry for my bad English.
FX2_DCF-Clock.h
typedef xdata struct signal { unsigned char sekunde; unsigned char minute; unsigned char stunde; unsigned char tag; unsigned char wochentag; unsigned char monat; unsigned char jahr; unsigned char synkro; unsigned int fehler_zaehler; }tdcf; extern tdcf dcf;
.
FX2_DCF-Clock.c
txdata tdcf dcf;
if(dcf.sekunde>59) { dcf.synkro=KEINSYNK; dcf.sekunde=0;
crash/stop
dcf.minute=0; dcf.stunde=0; }
"Why would that be necessary for an internal RAM data object?"
Not for the internal Ram but in the extern Ram it will be easier to read and write via usb vom a pc, if you now the address.
Locking a lot of things down to absolute addresses can quickly become problematic.
Sometimes it can be good to produce a "list-of-lists". One single data structure that contains the address and size of other structures.
Another thing to think about is that the structure may change depending on version. Knowing where it is doesn't imply that you know enough about its contents to really know how to read/write it.
Priority one must be a method to let the PC know what firmware version you have in your device.
It is quite common with:
typedef struct tag_1 { } tag_2;
tag_1 is the name it has within the "struct" namespace, i.e.:
struct node { struct node* next; int value; }; struct node *head; // ok node *tail; // invalid - "struct" keyword needed.
tag_2 is the type-defined name of the struct, i.e. intended for:
typedef struct { unsigned char age; char* name; } person_t; person_t charlie; person_t benny;