Funktionierendes CAN Bus Projekt entwickeln unter Bascom

[elkokiller]

Hallo Vitis,

ich habe jetzt eine Schaltung, analog zu der des CanTestBoard aufgebaut.
Die dort genutzten Pins musste ich etwas anpassen.

Den Code habe ich wie folgt angepasst:

$regfile = "m8def.dat"                                      ' ATMega8
$crystal = 7372800                                          ' Baudratenquarz der AVR (MCP2515 mit 16MHz)
$hwstack = 40                                               ' default use 32 for the hardware stack
$swstack = 80                                               ' default use 10 for the SW stack
$framesize = 90

Declare Sub Can_init()
Declare Sub Mcp2515_write(byval Reg_add As Byte , Byval Reg_val As Byte)
Declare Sub Mcp2515_bitmodify(byval Reg_add As Byte , Byval Reg_mask As Byte , Byval Reg_val As Byte)
Declare Function Mcp2515_read(byval Reg_add As Byte) As Byte

Mcp2515cs Alias Portb.4					    'MISO
Config Mcp2515cs = Output

Const Cmd_read = &H03                                       ' Read Command
Const Cmd_write = &H02                                      ' Write Command
Const Cmd_bitmodify = &H05                                  ' Bit-modify Command
Const Cmd_readstatus = &HA0                                 ' Read Status Command (poll)
Const Cmd_read_rx_status = &HB0
Const Cmd_reset = &HC0                                      ' Reset Command
Const Cmd_rts0 = &H81
Const Cmd_rts1 = &H82


Const Caninte = &H2B
Const Canctrl = &H0F
Const Canstat = &H0E                                        ' Statusregister
Const Eflg = &H2D                                           ' Error Flag Register
Const Cnf3 = &H28                                           ' Configuration Register 3
Const Cnf2 = &H29                                           ' Configuration Register 2
Const Cnf1 = &H2A                                           ' Configuration Register 1
Const Txb0ctrl = &B00110000                                 ' Transmit Buffer 0 Control Register
Const Txb0sidh = &B00110001                                 ' Transmit Buffer 0 Std Identifier High
Const Txb0sidl = &B00110010                                 ' Transmit Buffer 0 Std Identifier Low
Const Txb0eid8 = &B00110011                                 ' Transmit Buffer 0 Ext Identifier High
Const Txb0eid0 = &B00110100                                 ' Transmit Buffer 0 Ext Identifier Low
Const Txb0dlc = &B00110101                                  ' Transmit Buffer 0 Data Length Code
Const Txb0d0 = &B00110110                                   ' Transmit Buffer 0 Data Byte 0
Const Txb0d1 = &B00110111                                   ' Transmit Buffer 0 Data Byte 1
Const Txb0d2 = &B00111000                                   ' Transmit Buffer 0 Data Byte 2
Const Txb0d3 = &B00111001                                   ' Transmit Buffer 0 Data Byte 3
Const Txb0d4 = &B00111010                                   ' Transmit Buffer 0 Data Byte 4
Const Txb0d5 = &B00111011                                   ' Transmit Buffer 0 Data Byte 5
Const Txb0d6 = &B00111100                                   ' Transmit Buffer 0 Data Byte 6
Const Txb0d7 = &B00111101                                   ' Transmit Buffer 0 Data Byte 7
Const Rxm0sidh = &B00100000                                 ' Receive Buffer 0 Std Identifier High
Const Rxm0sidl = &B00100001                                 ' Receive Buffer 0 Std Identifier Low
Const Rxm0eid8 = &B00100010                                 ' Receive Buffer 0 Ext Identifier High
Const Rxm0eid0 = &B00100011                                 ' Receive Buffer 0 Ext Identifier low
Const Rxm1sidh = &B00100100                                 ' Receive Buffer 1 Std Identifier High
Const Rxm1sidl = &B00100101                                 ' Receive Buffer 1 Std Identifier Low
Const Rxm1eid8 = &B00100110                                 ' Receive Buffer 1 Ext Identifier High
Const Rxm1eid0 = &B00100111                                 ' Receive Buffer 1 Ext Identifier low

Const Rxb0ctrl = &H60
Const Rxb1ctrl = &H70


' Hardware SPI-Schnittstelle konfigurieren
'Config Portb.6 = Input		'Vitis
'Config Portb.5 = Output	'Vitis
'Config Portb.7 = Output	'Vitis

Config Portb.4 = Input
Config Portb.3 = Output
Config Portb.5 = Output
Spcr = &B01010010

'Config Pind.2 = Input		'Vitis
Config Pind.3 = Input
Config Int0 = Falling
On Int0 Int_canint
Enable Int0
Enable Interrupts

Call Can_init()

Do
   ' Zu übertragende Daten setzen:
   Mcp2515_bitmodify Txb0ctrl , &B00000011 , &B00000011     ' TX-Konfiguration
   Mcp2515_write Txb0sidh , &B01010101                      ' Empfängeradresse setzen
   Mcp2515_write Txb0sidl , &B01010101                      ' Empfängeradresse setzen
   Mcp2515_write Txb0dlc , &H04                             ' Paketlänge festlegen
   Mcp2515_write Txb0d0 , &B01010101                        ' Zu übertragende Daten setzen
   Mcp2515_write Txb0d1 , &B01010101                        ' Zu übertragende Daten setzen

   ' Übertragung auslösen
   Reset Mcp2515cs
   Waitus 10
   Spdr = Cmd_rts0
   Do
   Loop Until Spsr.spif = 1
   Waitus 10
   Set Mcp2515cs

Loop

Sub Can_init()
   Local Can_tmp As Byte

   Reset Mcp2515cs

   ' Reset MCP2515
   Can_tmp = Cmd_reset
   Spdr = Can_tmp
   Do
   Loop Until Spsr.spif = 1
   Set Mcp2515cs

   Waitms 2000
   Mcp2515_write Canctrl , &B10001000                       ' low nibble: 3=OSM 2=CLK-Pin 1-0=CLK Divider
   Print "speed change done"

   ' F MCP2515 = 16MHz
   Can_tmp = Eram_param_baudrate
   Select Case Can_tmp
      Case 0:
         ' CAN 31,25 KHz
         Mcp2515_write Cnf1 , &B00001111
      Case 1:
         ' CAN 62,5 KHz
         Mcp2515_write Cnf1 , &B00000111
      Case 2:
         ' CAN 125 KHz
         Mcp2515_write Cnf1 , &B00000011
      Case 3:
         ' CAN 250 KHz
         Mcp2515_write Cnf1 , &B00000001
      Case 4:
         ' CAN 500 KHz
         Mcp2515_write Cnf1 , &B00000000
      Case Else :
         Mcp2515_write Cnf1 , &B00001111
   End Select
   Mcp2515_write Cnf2 , &B10010000                          ' Cnf2 = &H29
   Mcp2515_write Cnf3 , &B00000010                          ' Cnf3 = &H28
   Mcp2515_write Caninte , &B00000011
   Mcp2515_write Rxb0ctrl , &B01100000
   Mcp2515_write Rxb1ctrl , &B01100000
   Mcp2515_write Rxm0sidh , 0                               ' Empfängeradressen auf 0, Filter aus
   Mcp2515_write Rxm0sidl , 0
   Mcp2515_write Rxm0eid8 , 0
   Mcp2515_write Rxm0eid0 , 0
   Mcp2515_write Rxm1sidh , 0
   Mcp2515_write Rxm1sidl , 0
   Mcp2515_write Rxm1eid8 , 0
   Mcp2515_write Rxm1eid0 , 0
   Mcp2515_bitmodify Canctrl , &B11100000 , &B00000000
   'Mcp2515_write Canctrl , &B00000000                       ' low nibble: 3=OSM 2=CLK-Pin 1-0=CLK Divider
   'Mcp2515_write Canctrl , &HE0
End Sub

Sub Mcp2515_bitmodify(reg_add , Reg_mask , Reg_val)
   Local Can_tmp2 As Byte
   Mcp2515cs = 0
   Can_tmp2 = Cmd_bitmodify
   Spdr = Can_tmp2
   Do
   Loop Until Spsr.spif = 1
   Waitms 2
   Spdr = Reg_add
   Do
   Loop Until Spsr.spif = 1
   Spdr = Reg_mask
   Do
   Loop Until Spsr.spif = 1
   Spdr = Reg_val
   Do
   Loop Until Spsr.spif = 1
   Mcp2515cs = 1
End Sub

Sub Mcp2515_write(reg_add , Reg_val)
   Local Can_tmp2 As Byte
   Mcp2515cs = 0
   Can_tmp2 = Cmd_write
   Spdr = Can_tmp2
   Do
   Loop Until Spsr.spif = 1
   Waitms 2
   Spdr = Reg_add
   Do
   Loop Until Spsr.spif = 1
   Spdr = Reg_val
   Do
   Loop Until Spsr.spif = 1
   Mcp2515cs = 1
End Sub


Function Mcp2515_read(reg_add)
   Local Can_tmp2 As Byte
   Mcp2515cs = 0
   Can_tmp2 = Cmd_read
   Spdr = Can_tmp2
   Do
   Loop Until Spsr.spif = 1
   Spdr = Reg_add
   Do
   Loop Until Spsr.spif = 1
   Spdr = 0
   Do
   Loop Until Spsr.spif = 1
   Mcp2515_read = Spdr
   Mcp2515cs = 1
End Function

Und jetzt gleich ein paar Fragen:
1. Die Adressierung der einzelnen Knoten spielt eine wichtige Rolle.
Wo ist die Adresse dieses Konoten festgelegt?
2. Verstehe ich es richtig dass der Empfängerknoten unter &B01010101 zu erreichen ist
3. Woraus leitest du die Peketlänge "&H04" ab?


Tobias