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Hacking up Honda's ECU
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PostPosted: Tue Oct 25, 2016 8:33 am 
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Joined: Mon Mar 07, 2016 1:40 pm
Posts: 24
Hi, i'm trying to remake something similare than the tool Flash N Burn is doing. Reading and writing chips on the burn2

I use the popular chip model SST27ST512, its a 64kb chips (0x0000 to 0xFFFF) file are 32kb (0x8000 to 0xFFFF)

exemple that I want to read 256bytes (from 0x8000 to 0x8100)

moates protocol :
Read from an SST27SF512 chip ....
Code:
'5'+'R'+n+MSB+LSB+CS


I use this Write array commands :
Code:
byte SendArray = new byte [6]{53, 82, 0, 128, 0, CS};
Serial.Write(SendArray, 0, 6);


1. = 5, for sst27sf512 chip model
2. = R, for reading the chips
3. = 0, for reading 256bytes
4. = 0x80, for region 0x8000
5. = 0x00, ending region 0x8000
6. = Checksum

What checksum do I use, and how do I dertermine it out ?

and now to poll back the reading, I only read 3F or FF, but none of the value I have on the chips. I tried 2 possible way.
First way :
Code:
byte bytesArray = new byte[256];

Serial.Read(bytesArray, 0, 256);

for (int i = 0; i < bytesArray.Length; i++)
     Console.Write(bytesArray[i]);


Second way :
Code:
for (int i = 0; i < 256; i++)
     Console.Write(Serial.ReadByte());


the blue leds trigger between on/off like it should, I really dont know what I do wrong.


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PostPosted: Tue Oct 25, 2016 4:16 pm 
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Joined: Mon Mar 07, 2016 1:40 pm
Posts: 24
i'Ve found it out, thread fixed

checksum actually is a checksum of the commands.

for the commands 53,82,0,128,0
we calculate like so : 53 + 82 + 0 + 128 = 263
since 263 is over 1byte value. we extract 1byte : 263 - 256 = 7

New commands with checksum :

53,82,0,128,0,7

and now i'm able to read back the bytes


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