patch 14MZ .mdl files to work with 12Z

[andersnorlin]

Is it possible to patch 14MZ .mdl files to work with 12Z? Change model name in .mdl file.

[RCfan]

Yes. You have to change the model name bytes starting at file offset 0x1e (note they're UNICODE), and then calculate two 32-bit checksums (one for the first 0xb8 bytes, store in 0xb8-0xbb), and then one for the whole file after updating the first chksum (bytes 0-0x1fffb, store in 0x1fffc-1ffff). Checksums are byte-by-byte sum.

[andersnorlin]

Originally Posted by RCfan

Yes. You have to change the model name bytes starting at file offset 0x1e (note they're UNICODE), and then calculate two 32-bit checksums (one for the first 0xb8 bytes, store in 0xb8-0xbb), and then one for the whole file (bytes 0-0x1fffb, store in 0x1fffc-1ffff) after updating the first chksum. Checksums are byte-2-byte sum.

fast answer, thank's. Any GUI:s for doing this?

[RCfan]

Any GUI:s for doing this?

Yes, the 14MZ GUI! :mrgreen:

[andersnorlin]

Originally Posted by RCfan

Yes, the 14MZ GUI! :mrgreen:

Do you use a HEX editor that computes Checksums, byte-by-byte sum. I have Cygnus but it seems to calculate wrong checksum.

[RCfan]

Some (hex) editors let you calculate checksums using different algorithms. Just remember you'll need to get a 32-bit checksum using byte-by-byte sums, i.e. each individual byte is added to a running total, the checksum. I wrote myself a small one that runs under cygwin.

[andersnorlin]

Originally Posted by RCfan

Yes, the 14MZ GUI! :mrgreen:

Ok, I got it to work. Do you also know how to change the frequency band in the .mdl file. My mdl file uses 72MHz and I want to change to 35MHz. Does not seem to work to change it after reading in the model file in the transmitter.

[andersnorlin]

Originally Posted by andersnorlin

Ok, I got it to work. Do you also know how to change the frequency band in the .mdl file. My mdl file uses 72MHz and I want to change to 35MHz. Does not seem to work to change it after reading in the model file in the transmitter.

Nevermind I found your earlier post of the structure in the .mdl file.

Thank's

[andersnorlin]

This does not seem to work

0x00062- modulation (0=G3, 1=PCM, 2=PPM)
0x00063- region code? (0=America, 1=?, 2=Europe/UK)
0x00064- frequency code? (2=35MHz, 7=72MHz)
0x00065- Channel index (for 72Mhz, 1=ch11, 2=ch12, ... 0x17=ch33

I set

0x00062- 0
0x00063- 2
0x00064- 2
0x00065- 1

calculate new checksums.

And when loading patched .mdl file it still want's to use 72MHz band.

What am I doing wrong here?
:?

[andersnorlin]

Originally Posted by andersnorlin

This does not seem to work

0x00062- modulation (0=G3, 1=PCM, 2=PPM)
0x00063- region code? (0=America, 1=?, 2=Europe/UK)
0x00064- frequency code? (2=35MHz, 7=72MHz)
0x00065- Channel index (for 72Mhz, 1=ch11, 2=ch12, ... 0x17=ch33

I set

0x00062- 0
0x00063- 2
0x00064- 2
0x00065- 1

calculate new checksums.

And when loading patched .mdl file it still want's to use 72MHz band.

What am I doing wrong here?
:?

Is there a cheecksum for the frequency data block? Index?