MCLoader & XPort

[Joe Rocci]

Jumper,

OK, I think I have it. In the .lib file, there was another ORG statement further down that was apparently overriding the special ORG DEFINE that we put in. It looked like this:
ORG RESET_ORG ; Reset vector at 0

I commented it out, and all seems to work OK now, org'ing at 0 if nothing is specified and ORG'ing at 60160 using your special DEFINE to select the desired starting location.


Joe

[Jumper]

We need the DEFINE RESET_ORG in the lib file when we write the application software to move the code to a suitable address (I like 64).

Have you tried if that part works?


/me

[Charles Linquis]

I think this is a worthwhile project, but don't forget those of us that use parts with more than 64K of code space!

[mister_e]

I agree. Funny... those i did with more than 64K, as now, don't use the bootloader, just ICSP. Case by case i guess.

[Jumper]

Sure it would be nice if all PIC's could be using this loader but:

How do we address the memory above 65535 ($FFFF) in READCODE and
WRITECODE when PBP only have 16-bit variables. It seems to me that Microchip has outgrown PBP, 32-bit variables in PBP would be nice.

ICSP is probably the way to go, unless it is done in ASM.

Let's start with the 64K devices and see if we run into any mines. We are still far from finished.....

/me

[Joe Rocci]

Good morning all!
(well morning my time...where is everyone else from?)

An update on the project so far:

1) We have a custom PBP DEFINE to specify where our bootloader should be in memory (needs to be checked further per Jumper's previous)
2) I've written and compiled test code with the new DEFINE, and the resultant program truly does locate where it should be and run properly
3) I wrote a little program that resides in 'remote' loader memory (ORG'd at 60160d) and writes a block of data to 'low' memory space starting at 0. This data block consists of 256 incrementing values starting at 0h and ending in FFh.

I'm having a small problem with the last part. The data that I read back from memory is correct for the most part, but every 8th memory location has a "0" instead of the correct value. I don't have the code in front of me to attach, but I'll send it when I get back to my office later this morning. Basically though, the sequence of events is:

A) Dump the 256 byte memory block to Hyperterminal using READCODE
B) Do a 64-byte block erase using ERASECODE
C) Rewrite each byte in the block just erased using WRITECODE
D) Repeat for a total of 256 bytes
E) Dump the re-written memory values to Hyperterminal

If you want to cogitate on this for a while and speculate on what I might be doing wrong, I'll get you with some more details later. I think that once we get through this, we're on our way!

BTW, in regard to programming bigger (>64K) parts, maybe we can fall back to using a little bit of embedded assembly code. Check out the OshonSoft web site for an example of how simple it can be:

http://www.oshonsoft.com/pic18bootloader.html


Joe

[Joe Rocci]

Ok, as promised, here is the code and the result that I described earlier:

CODE:

INIT: HSEROUt [$0D,$0A,$0D,$0A] 'Make space between display dumps
FOR I = 0 TO 255 step 16 'Dump 512 memory locations to screen
hserout [hex4(i), ":: "]
for j = 0 to 15 '16 bytes per line
READCODE (i+J),X
hserout [":", HEX2(X)," "]
next j
hserout [$0A, $0D] 'Line break after each line
next i
HSERin [x] 'Start on "L" from keyboard
if x="L" then
Goto Loader
ENDIF
'************************************************* ******************************
Loader:
for j = 0 to 255 step 64 'Erasecode does 64 bytes per block
erasecode j 'Erase a block
for i = 0 to 63 'Write 64 bytes
writecode i+j,i+j 'Write the block that was just erased
next i
next j 'Keep going until done

goto INIT 'Print out the result and wait




and here is a partial of the screen dump:

0000:: :00 :01 :02 :03 :04 :05 :06 :00 :08 :09 :0A :0B :0C :0D :0E :00
0010:: :10 :11 :12 :13 :14 :15 :16 :00 :18 :19 :1A :1B :1C :1D :1E :00
0020:: :20 :21 :22 :23 :24 :25 :26 :00 :28 :29 :2A :2B :2C :2D :2E :00
0030:: :30 :31 :32 :33 :34 :35 :36 :00 :38 :39 :3A :3B :3C :3D :3E :00
0040:: :40 :41 :42 :43 :44 :45 :46 :00 :48 :49 :4A :4B :4C :4D :4E :00
0050:: :50 :51 :52 :53 :54 :55 :56 :00 :58 :59 :5A :5B :5C :5D :5E :00