PSA algorithm on GANG430

Hey,

I try to implement the communication with a GANG430 programmer in python.

To get an idea how it work i sniffed on the serial port.

There are same things I don't understand.

First: the PSA algorithm

this is the sample code in c: (from the Manual rev Q)

for (PSA = StartAddr - 2, i = 0; i < Length; i++) { if (PSA & 0x8000) PSA = ((PSA ^
0x0805) << 1) | 1; else PSA <<= 1; PSA ^= Data[i]; }

This is what i have done in python:

psa=DEF_MAIN_START-2
for i in range(0,DEF_MAIN_LENGTH,1):
          if psa & 0x8000:
             psa = (((psa ^ 0x0805)<<1) | 1)
         else:
            psa <<=1
                            
        psa ^= data[i]

I feeded my python script with the same firmeware but cann't get the same PSA checksum from sniffing the port.

Second: in the manual for the GANG430  under 3.5.10 Load Image Checksum

the bytes  D9 : should be MSByte of the start address

and           D11: should be LSByte of the start address

same for the length  byte D12 : MSB and D14 : LSB

but I  can't see this in my sniffed sample....there is D9: LSB und D11:MSB....and the same for D12: LSB -D14 : MSB

Is this a fault in the manual???

Thanks in advance.

Regards,

Kay