Page 5 of 43
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 5:44 pm
by festy
Think I might have just found the dash checksum
Any chance you can read that other dash's chip the same as you did this one?
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 5:51 pm
by antus
Last time I tried there was checksums for the values, then a global one for the whole thing but you could work around it by swapping bytes, as being just a sum, not a CRC that doesnt break the sums. Can get it ballpark to what your looking for by clicking over the least significant digits then swapping.
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 6:03 pm
by festy
Code: Select all
00000000 ff ff ff ff ff ff 00 ff ff ff ff ff ff ff d3 2c |...............,|
00000010 00 00 00 00 00 00 25 da 00 00 00 00 00 00 09 f6 |......%.........|
00000020
f6^da = 2c
09^25 = 2c
2c^d3 = ff
Probably more to it, but that's definitely a checksum. There might be a CRC check against words 4-7, hard to tell with only one sample.
Does this dash use a 1250ppk VSS?
Because 0x90f6 * 1250 = 3187500
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 6:21 pm
by Streetholden
Wow, you guys are really into it. Youve got me lost so far. Last time i checked the post i was asked for some numbers and such, went to upload some pictures then saw this.
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 7:12 pm
by VL400
Yeah you get that around here, lots of keen hackers
Nice work festy
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 7:33 pm
by festy
So getting back to re-programming via connector CN103, it has 5 pins - are they 5v, gnd, and clock,data in/data out to the 24C44, or are they to a uart on the 8051?
I've found an old 8051 of unknown origin to use as a guinnea pig so will try to put together a rom dumping circuit at some point in the future.
I'll need 25 I/O lines to read the 8051 so a pic16f877 would probably do the job.
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 9:32 pm
by festy
VL400 wrote:Both of my programmers dont support it
So would need to be a pic/avr to read it like festy suggested. Would be interesting to get the MCU code out too
A Willem PCB3 clone should be able to read and write the 24C44 using software version 0.97ja, select "S24H45" for the device.
Or
here's an ebay ICSP programmer for $20 that will do them too.
Re: Couldnt really find a section for this..
Posted: Sat Jul 16, 2011 11:50 pm
by The1
Just found the facia for this one I usually label all my parts it had 358100 on it
Re: Couldnt really find a section for this..
Posted: Sun Jul 17, 2011 12:15 am
by The1
I'll have a look and see if I can read another one tomorrow and do some tracing
Re: Couldnt really find a section for this..
Posted: Sun Jul 17, 2011 12:18 am
by The1
festy wrote:VL400 wrote:Both of my programmers dont support it
So would need to be a pic/avr to read it like festy suggested. Would be interesting to get the MCU code out too
A Willem PCB3 clone should be able to read and write the 24C44 using software version 0.97ja, select "S24H45" for the device.
Or
here's an ebay ICSP programmer for $20 that will do them too.
Cool I'll have a look