Read register in C

[Lettin03]

In my code I have to read the registers that I it uses, therefore I will use this function

void leesRegister( unsigned char* Register )

The microcontroller is a Fujitsu MB90F497 and the registers I use are

DDR0;
DDR2;
DDR4;

Is there someone who can help me to find the right structure to read these registers? I have looked up on the internet and the datasheet but not very succesfull. The datasheet can be found here http://www.alldatasheet.co.kr/datash.../MB90F497.html

[matsp]

On page 19 [as numbered in the document, not PDF reader's pages]:
Address 2: 0x4000

Address 2 is the base-address for extension IO addresses.

The DDR registers are listed on page 20 of the document.

To actually access these registers, you need a unsigned char pointer that points to the relevant address:

#define IOBASE 0x4000
unsigned char *DDR0 = (unsigned char *)(IOBASE + 0x10);
...
   unsigned char value = *DDR0;
...

--
Mats

[Lettin03]

Thank you very much, this is not the whole code I assume? Could you explain the code just a little bit?

(IOBASE + 0x10);

especially this code above. Thank you in advance

[matsp]

Thank you very much, this is not the whole code I assume? Could you explain the code just a little bit?

(IOBASE + 0x10);

especially this code above. Thank you in advance

IOBASE (which expands to 0x4000) is the address of the IO region according to page 19 of the document. DDR0 has the address 0x10 according to the following page, so we add that to the base-address. [Could make a further define for that if we wish, but it seems meaningless].

Once you have those two together, you know the address of that register, right? So now we just need to create a pointer, whcih is the bit that I do in the "unsigned char *DDR0 = (unsigned char *)(IOBASE + 0x10);". The cast is there to tell the compiler "I know this is not a pointer in your opinion, but let's make it a pointer anyways" [IOBASE + 0x10 is not a pointer in the compilers opinion, since it's just integer values].

--
Mats

[Lettin03]

Oke that part I understand now, thank you for the explenation. However, don't I have to declare value? and the argument Register is unused. After compiling I get an error

E4159C: redefinition of identifier `value'
I0001C: previous declaration of `value': "c:\documents and settings\gr_mstag2\desktop\lettinga_henk\project\
        software\leesregister.c", line 6
W1021C: parameter `Register' unused in function `leesRegister'

Can you explain to me how to fix these errors?

[matsp]

I don't know what your function does - and my example wasn't complete by any means.

--
Mats