bootloader that xfers code from I2C into program memory

[pedja089]

I use 18F series for all my project.
You can just compile some code for 16F, something like
DEFINE RESET_ORG 16
pause 1
And you should get 16 bytes FF then some other values. Also to view content of hex file you could use any programmer software, but I prefer MPLAB X, because I can export HEX values of just piece of hex to text file, and format it to ASM sintax.
Then let us know
I don't know what 16F part are able to do flash write. And also flash size is critical.
So I think any way, better to go with some 18F that have twice flash you need, so you could use flash to flash bootloader. It's really neat, small, simple and doesn't require any external parts!
All this can be done in ASM to get even smaller bootloaders, but I just didn't bother with that.
By the way all 18F can do code erase, write and read eaven if it is locked. Code protect bit affect only ICSP.

[picster]

This is definitely a great starting point. I'll test with some simple stuff and then see how it works out on the PIC I'm using. Might be just what I needed.

picster

[picster]

Ok so looking at the code, I had a couple of questions - I'm hoping you can clarify for me.

1) Flashbyte2 and Flashbyte3 - redundant copies, with the same data 3 times in i2c eeprom?

2) What is the purpose of EraseStr VAR BYTE[128]? I don't see it elsewhere in the pasted code.

3) Lastly, in the ASM portion, you start each line with dw - is this just to "define words" (hex format little-endian) that will simply sit there in memory until you jump to the label?

I really appreciate your posting this, it's hugely helpful.

Picster

[pedja089]

1) Redundant read of same memory location. Just to be sure that there is no error in communication. Same at writing, write 32 bytes, then read them, and compare. Just to on safe side.
2) Scroll little bit down

'Optional Erase I2C EEPROM
    FOR Adr=0 TO 79999 STEP 128
        MAdr=Adr.WORD0
        MCtrl=$A0 + ((Adr.BYTE2 & %00000011)<<1)
     BootI2CW:
        I2CWRITE Mem_Sda,Mem_Scl,MCtrl,MAdr,[STR EraseStr\128],BootI2CW
        PAUSE 5

Just easy way to dump 128 zeros in memory.
3) Not sure what you are asking, but that is code for bootloader in main app. That code will sit there forever. And execute when jump to label.
Output of first 32 line from random project in MPLAB X program windows(right click output to file)

       Line      Address       Opcode           Label                        DisAssy                 
        1    00000         EF30                             GOTO 0x260                               
        2    00002         F001                             NOP                                      
        3    00004         FFFF                             NOP                                      
        4    00006         FFFF                             NOP                                      
        5    00008         0012                             RETURN 0                                 
        6    0000A         FFFF                             NOP                                      
        7    0000C         FFFF                             NOP                                      
        8    0000E         FFFF                             NOP                                      
        9    00010         FFFF                             NOP                                      
       10    00012         FFFF                             NOP                                      
       11    00014         FFFF                             NOP                                      
       12    00016         FFFF                             NOP                                      
       13    00018         0012                             RETURN 0                                 
       14    0001A         010F         HSEROUT             MOVLB 0xF                                
       15    0001C         0004         hseroutloop         CLRWDT                                   
       16    0001E         A89E                             BTFSS PIR1, 4, ACCESS                    
       17    00020         D7FD                             BRA hseroutloop

Similar thing you will get when compile bootloader, but at different start address. And you need to copy opcode column to to your main program and address must lineup.
I'm not sure that I answered your question.

[picster]

Got it, thanks.

Makes sense

picster

[pedja089]

Great!
Did you try to compile code for 16F with RESET_ORG?

[picster]

YUP, and it worked fine Had to download MPLABX before continuing...

I'll be writing a small program for Windows to xfer the code via RS-232 INTO the I2C EEPROM (which the Pic's main program will manage), in order to test it properly. Weekend stuff.

Will let you know how it works out, but this looks really promising, thanks again!