I think there are some PIC18s without any internal flash or ROM that 
make the program memory bus available to the outside world.  Maybe it's 
for that.

Henry

Phillip wrote:
> Hi John
> Thanks for the reply.
> (Now I'm really confuzed!)
> I'm more than a little fuzzy here so bear with me.
> Why would you write data to the program memory bus but not program memory
> its self?.....unless there was device on the program memory bus that needed
> the data other than program memory?
> If I look at the block diagram I don't even see a connection to the outside
> world.
>
>
> I thought/assumed (most likely incorrectly) that what was this function i.e.
> memmoveram2pgm (and the other similar functions) did underneath was to do
> TABLE reads and writes to program memory.
> If you step into the function with the debugger it looks like that is what
> it is doing (but I can't really tell for certain what it is doing in there
> exactly)
> I can't figure what these functions are for unless they do this?
>
> Technically speaking program memory is the EEPROM?......ummm right???
> I thought I only had access to a portion of it.
> In this case a 18F6520 I have access/ ability to read/write to 1024 bytes on
> one end?
> I thought that (magically) these functions could do table reads and writes
> in rest of program memory.
>
> Thanks in advance for clearing this up for me.
>
> Phillip
> Things should be as simple as possible but no simpler
>  
>  
>  
> Phillip Coiner
> CTO, GPS Source, Inc.
>  
>  
> Your source for quality GNSS Networking Solutions and Design Services, Now!
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
> piclist@xargs.com
> Sent: Wednesday, June 07, 2006 12:48 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] how do I get from ram to rom in C18
>
> On Wed, 7 Jun 2006, Phillip wrote:
>
>   
>> Can anyone tell me how to get the data in the var holder to the var
>> atten_setting?
>>     
>
> The "2pgm" functions write data to the program memory bus.  They do
> not write to the PIC's program memory.  If you really need to write to
> the PIC's program memory, you'll have to follow the flash write
> procedure outlined in your PIC's datasheet (assuming your PIC supports
> this feature).
>
> EEPROM might be a better choice.
>
>   
>> I was under the impression that atten_string is in program memory and that
>> holder is an auto variable in data memory.
>>
>> I'm also "assuming" the function memmoveram2pgm would move the value in
>> holder (which has the correct data when I view in the debugger) to
>> atten_setting.
>>
>> This is not working but I can't see why not any sugestions out there?
>>
>> rom char atten_string[6];
>>
>> void  Attenuation_adjust(void)
>>
>> {
>>
>> char holder[6];
>>
>>  unsigned long x;
>>
>>  unsigned char RF_atten_setting;
>>
>>  RF_atten_setting = read_RF_Atten();
>>
>>  x = RF_atten_setting;
>>
>>  ultoa(x,holder);
>>
>> memmoveram2pgm(atten_string,holder);
>>     
>
> --
> John W. Temples, III
>   

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