External RAM & EPROM

 External RAM & EPROM

Hi All. Its hard for me to determine where to start asking my question. I understand you wont be able to tell me whats specifically wrong, but if you could help give me some ideas of issues to check, I would greatly appreciate it.

Ok, we have a project which consists of Intel 80c321, RAM, 256Eprom and a memory mapped FPGA. Originally, the project was compiled by Achimedes (bought by Keil). This project is well before my time and all the original engineers are gone.

I compile my code with no problems (other than a few expected compiler warnings). The system starts up which is apparent because I have a serial link to the device.

What does not appear to be happening is the proper interaction with the FPGA. I imagine there is an issue with my XDATA configuration. I was not sure if banking was used although I doubt it. If the banking were used shouldnt I expect HDATA in the map file?

I have not changed any code from the original source yet so that leads me to believe this is a 'setting' issue.

There are definitions like: static unsigned char xdata IOActuatorPort _at_ 0xB000;

Then we access them using:

unsigned char IOReadPort(unsigned int addr)
{
    unsigned char *port;

    port = (unsigned char *) addr;                         /* Assign the address to the memory pointer.              */

    return(*port);                                         /* Read the memory and return the value to caller.        */
}

void IOWritePort(unsigned int addr, unsigned char value)
{
    unsigned char *port;

    port  = (unsigned char *) addr;                        /* Assign the address to the memory pointer.              */
    *port = value;                                         /* Write the data to the memory location.                 */
}

I have the source and a version that was compiled already (along with map file, etc) that works. Is there any comparison I can do between the old/new MAP files? I imagine not since this is a different version of compiler... no doubt it would be different.

Thanks in advance for any insight you can give me into this issue!
Chris

 RE: External RAM & EPROM

port  = (unsigned char *) addr;

Chris,

Read up on memory specific pointers and generic pointers in your Keil C51 manual and re-write this line based on your new understanding.

 RE: External RAM & EPROM

Your advice is DULLY noted! Hmm such a small lack of a keyword to destroy my project. All fixed!

I am still abit confused as to why this worked in the past. Different compiler perhaps?

 RE: External RAM & EPROM

Ouch, thats 'sposed to be DULY not DULLY. lol. I assure you it was not dull, I did a heel click when it worked.

Thanks again sir.

And just for those who might search this later the answer is:

unsigned char xdata *port;