Bascom Bootloader verstehen

[Otto U (Gast)]

Hallo
Ich versuche gerade den Bascom Mcs Bootloader zu verstehen.
Ich möchte den Avr aus meinem Programm heraus flashen können.
Also aus Bascom heraus funktioniert der Bootloader.
Im grunde denke ich auch das ich ihn verstanden habe. Aber ich habe am 
ende eine andere Checksumme als der Bootloader erwartet.
Also aufbau der Komunikation

Der Pc sendet Byte 123
Bootloader antwortet mit 21
Pc sendet 1 für Start
Pc sendet Block nummer 1 für die die erste
Pc sendet 1. checksume Dafür sehe ich keine verwendung?
Pc sendet 128 daten bytes
pc sendet 2. Checksumme diese muss alles incl 1. eins endhalten ?!
darauf antwortet der Bootloader mit ack oder eben wie bei mir immer nack

Nun verstehe ich einfach nicht wofür ist die erste Checksumme ?

' (c) 1995-2009, MCS VERSION 2 of the BOOTLOADER. The waiting for the NAK is
' stretched.further a bug was resolved for the M64/128 that have a big page size
'-------------------------------------------------------------------------------
$crystal = 16000000
$baud = 9600


$regfile = "M328def.dat"
Const Loaderchip = 328


$prog &HFF , &H7F , &HD8 , &H00                             ' generated. Take care that the chip supports all fuse bytes.

#if Loaderchip = 328                                        ' Mega32
    $loader = $3c00                                         ' 1024 words
    Const Maxwordbit = 6                                    'Z6 is maximum bit                                   '
    Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0
#endif


Const Maxword =(2 ^ Maxwordbit) * 2                         '128
Const Maxwordshift = Maxwordbit + 1

'Dim the used variables
Dim Bstatus As Byte , Bretries As Byte , Bblock As Byte , Bblocklocal As Byte
Dim Bcsum1 As Byte , Bcsum2 As Byte , Buf(128) As Byte , Csum As Byte
Dim J As Byte , Spmcrval As Byte                            ' self program command byte value

Dim Z As Long                                               'this is the Z pointer word
Dim Vl As Byte , Vh As Byte                                 ' these bytes are used for the data values
Dim Wrd As Word , Page As Word                              'these vars contain the page and word address
Dim Bkind As Byte , Bstarted As Byte
'Mega 88 : 32 words, 128 pages

Disable Interrupts                                          'we do not use ints

'Waitms 100                                                  'wait 100 msec sec
'We start with receiving a file. The PC must send this binary file

'some constants used in serial com
Const Nak = &H15
Const Ack = &H06
Const Can = &H18

$timeout = 400000                                           'we use a timeout
'When you get LOADER errors during the upload, increase the timeout value
'for example at 16 Mhz, use 200000

Bretries = 5                                                'we try 5 times
Testfor123:

Bstatus = Waitkey()                                         ' wait for the loader to send a byte

Print Chr(bstatus);                                         ' got - return value

If Bstatus = 123 Then                                       'did we received value 123 ?
   Bkind = 0                                                'normal flash loader
   Goto Loader
Elseif Bstatus = 124 Then                                   ' EEPROM
   Bkind = 1                                                ' EEPROM loader
   Goto Loader
Elseif Bstatus <> 0 Then
   Decr Bretries
   If Bretries <> 0 Then Goto Testfor123                    'we test again
End If

'For J = 1 To 10                                             'this is a simple indication that we start the normal reset vector
'   Toggle Portb.2 : Waitms 100
'Next

Goto _reset                                                 'goto the normal reset vector at address 0

'---[this is the loader routine. It is a Xmodem-checksum reception routine]-----
Loader:
  Do                                                        'Clear buffer
     Bstatus = Waitkey()
  Loop Until Bstatus = 0

'  For J = 1 To 3                                            'this is a simple indication that we start the normal reset vector
'     Toggle Portb.2 : Waitms 50
'  Next

  If Bkind = 0 Then
     Spmcrval = 3 : Gosub Do_spm                            ' erase  the first page
     Spmcrval = 17 : Gosub Do_spm                           ' re-enable page
  End If

Bretries = 10                                               'number of retries

'Blockaufbau:
'------------
' Das ASCII-Zeichen Start Of Header (SOH, hex01) (1 Byte),
' Blocknummer (1 Byte), 0...255
' Daten (128 Byte),
' Prüfsumme (1 Byte) die Prüfsumme ist hier die arithmetische Summe der Datenbytes modulo 256 und deshalb fehleranfällig

'Protokoll:
'----------
' Die Übertragung wird durch den Empfänger angestoßen, indem er ein NAK sendet.
 'Eine fehlerfrei empfangene Checksumme wird mit Acknowledgement (ACK, hex06) bestätigt.
' Bei einer Checksumme ungleich der berechneten Checksumme ist ein Fehler aufgetreten.
' Der Block wird mit Negative Acknowledgement (NAK, hex15) abgelehnt und dann bis zu zehnmal neu versendet.
' Das Ende einer Übertragung wird vom Sender mit End Of Transmission (EOT, hex04) angezeigt.
' Auch dieses muss mit einem ACK bestätigt werden.

Do
  Bstarted = 0                                              ' we were not started yet
  Csum = 0                                                  'checksum is 0 when we start
  Print Chr(nak);                                           ' first time send a nack
  Do

    Bstatus = Waitkey()                                     'wait for status byte

    Select Case Bstatus
       Case 1:                                              ' start of heading, PC is ready to send (hex01)
            Incr Bblocklocal                                ' increase local block count

            Csum = 1                                        ' checksum is 1

            Bblock = Waitkey() : Csum = Csum + Bblock       'get block-number

            Bcsum1 = Waitkey() : Csum = Csum + Bcsum1       'get checksum first-byte

            For J = 1 To 128                                'get 128 bytes (Data)
              Buf(j) = Waitkey() : Csum = Csum + Buf(j)
            Next

            Bcsum2 = Waitkey()                              'get second checksum byte

            If Bblocklocal = Bblock Then                    'are the blocks the same?
               If Bcsum2 = Csum Then                        'is the checksum the same?
                  Gosub Writepage                           'yes go write the page
                  Print Chr(ack);                           'acknowledge
               Else                                         'no match so send nak
                  Print Chr(nak);
               End If
            Else
               Print Chr(nak);                              'blocks do not match
            End If
       Case 4:                                              ' end of transmission , file is transmitted
             If Wrd > 0 And Bkind = 0 Then                  ' if there was something left in the page
                 Wrd = 0                                    'Z pointer needs wrd to be 0
                 Spmcrval = 5 : Gosub Do_spm                'write page
                 Spmcrval = 17 : Gosub Do_spm               ' re-enable page
             End If
             Print Chr(ack);                                ' send ack and ready

'             Portb.3 = 0                                    ' simple indication that we are finished and ok
             Waitms 20
             Goto _reset                                    ' start new program
       Case &H18:                                           ' PC aborts transmission
             Goto _reset                                    ' ready
       Case 123 : Exit Do                                   'was probably still in the buffer
       Case 124 : Exit Do
       Case Else
          Exit Do                                           ' no valid data
    End Select
  Loop

  If Bretries > 0 Then                                      'attempte left?
     Waitms 1000
     Decr Bretries                                          'decrease attempts
  Else
     Goto _reset                                            'reset chip
  End If

Loop

'---[write one or more pages]---------------------------------------------------
Writepage:
 If Bkind = 0 Then
   For J = 1 To 128 Step 2                                  'we write 2 bytes into a page
      Vl = Buf(j) : Vh = Buf(j + 1)                         'get Low and High bytes
      lds r0, {vl}                                          'store them into r0 and r1 registers
      lds r1, {vh}
      Spmcrval = 1 : Gosub Do_spm                           'write value into page at word address
      Wrd = Wrd + 2                                         ' word address increases with 2 because LS bit of Z is not used
      If Wrd = Maxword Then                                 ' page is full
          Wrd = 0                                           'Z pointer needs wrd to be 0
          Spmcrval = 5 : Gosub Do_spm                       'write page
          Spmcrval = 17 : Gosub Do_spm                      ' re-enable page

          Page = Page + 1                                   'next page
          Spmcrval = 3 : Gosub Do_spm                       ' erase  next page
          Spmcrval = 17 : Gosub Do_spm                      ' re-enable page
      End If
   Next

 Else                                                       'eeprom
     For J = 1 To 128
       Writeeeprom Buf(j) , Wrd
       Wrd = Wrd + 1
     Next
 End If
Return

Do_spm:
  Bitwait Spmcsr.0 , Reset                                  ' check for previous SPM complete
  Bitwait Eecr.1 , Reset                                    'wait for eeprom

  Z = Page                                                  'make equal to page
  Shift Z , Left , Maxwordshift                             'shift to proper place
  Z = Z + Wrd                                               'add word
  lds r30,{Z}
  lds r31,{Z+1}

  #if _romsize > 65536
      lds r24,{Z+2}
      sts rampz,r24                                         ' we need to set rampz also for the M128
  #endif

  Spmcsr = Spmcrval                                         'assign register
  spm                                                       'this is an asm instruction
  nop
  nop
Return

[Michael U. (amiga)]

Hallo,

die Übertragung sieht ja so nach altem X-Modem aus...

Gruß aus Berlin
Michael