Help with writecode needed

[Marten]

Hi

I have been trying to use writecode on my 18F252 for a while, but i seem to fail whatever i do :(

I need a simple code example to get me going, i have looked at Melanies posts about the subject, but i need more concrete advice.

I'm trying to copy the contents from one adress in codespace to another.

if someone could write a few lines and show me how it's supposed to be done, with readcode,erasecode,eecon and all, please ?

use $FE0 --> $FF0 or something.

I have PicBasic Pro 2.42,have not used PBP for long, i 'm migrating from AtomBasic > PBP, so far so good, but my adventures with writecode makes my head spin.

Marten

[mister_e]

probably you'll need an update. Here's a quote from Melabs Website


When using WRITECODE to store data in the code space of these parts, you have to use a block-write method. This different than some of the other self-programming devices like the 16F87x, which will allow you to write a single location. Refer to the Microchip datasheet for more information.

The 18F parts have recently been introduced by Microchip. As with all new technology, they are not perfect. We have corrected for all the anomalies that we can in our development tools, but there is a chance that you may find a problem that affects your application. It's a good idea to check the Microchip website for current posting of errata concerning these parts


At this link (http://www.melabs.com/support/mcu_hints.htm)

[Marten]

Thanks, i have spent some time in the datasheet for the 252, done some "Rtfm" and tried to figure it out, but i still don't get it right, could you give me some sample code ?


In my world i thought that you could do a read and a' write
like

read $FF0,variable
write $FF0,variable

I have used read and write before, stored data in eeprom and so on, but i seem to stupid when it comes to doing byte-write stuff, please help ...





Marten

[mister_e]

i'm confused, do you want to read/write from CODESPACE or EEPROM

READ/WRITE = Internal EEPROM
READCODE WRITECODE = code space

i'm not a fan of Writecode and readcode, but i think you must use a WORD sized variable to do that on those 18Fs series

[Marten]

Sorry for the confusion !

What i mean, what i am trying to do, is to copy parts of code from one adress in codespace to another, in the same way that you use read and write with eeprom, i'm going to use this function to update code in a 18F252 from an smartcard later on, i simply have to learn how it all works first.

what i have tried to do is the following:

'Lcd Defines removed from code snip'

define osc 20

snip1 var word
snip2 var word


erasecode $7FF

readcode $000,snip1
pause 50
writecode $7FF,snip1
pause 50
readcode $7FF,snip2

LCDOUT $FE,1,"Orig: ",hex snip1
LCDOUT $FE,$C0, "Copy: ",hex snip2


This, does not work, snip1 and 2 does not have the same value,and it is many things that may be wrong, and i do not know what at the moment, the data sheet says that i must perform a block write with 8 bytes, something i dont understand how, without a array variable 'str var\8' or something like it, that is whats bugging me .

Could you or anyone tell me how to proceed, is there any configuration bit that i cant see ?, i have checked all the bits in 18F252.inc and P18F252 and everything that sounds like write protection is disabled.


Marten