Lin-bus

Ghitab · Joined: 25 Sep 2012 Posts: 10

Hi. I'm playing with a vw steering wheel based on lin bus(2.0). I use an atmega32m1 and tja 1020 as transceiver. I manage to send id and steering wheel respond, but i can't read or i don't understend from datasheet how is LINDAT loaded. I have no error in lin error flag register. Any help is apreciated.
Thank you.

$regfile = "m32m1.dat"
$crystal = 16000000
$hwstack = 100
$swstack = 150
$framesize = 400

Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Portc.7 , Db5 = Portb.4 , Db6 = Portb.3 , Db7 = Portc.6 , E = Portb.5 , Rs = Portb.6
Cursor Off
Cls
Config Portc.1 = Output 'enable tja transceiver

Set Portc.1
Lcd "test lin"
Wait 1
Cls
Dim A( Cool

As Byte
Dim B As Byte

Linbtr = 160 'disable resync,
Linbrrl = 25 'baudrate 19200
Linbrrh = 0

Lincr = &B00001000 'rx header

Lindlr = &B00011000 '1 tx byte, 8 rx byte

Linenir = &B00000001 'receive interupt enable

Linsel = &B00000000 'autoincremet fifo
Do
Locate 1 , 1
Lcd A(2) ; " " ; Lrxok ; " " ; Linsir.4
Locate 2 , 1
Lcd Lincr ; " " ; Linsir ; " " ; Linerr ;
Waitms 10

Linidr = &B10001110 'id 8E to read button's
'Linidr = &B10111010 'id BA
Lincr = &B00001001 'header + id

For B = 1 To 8
A(b) = Lindat
Next

Loop
//---------------------------------

00 55 8E from master,

F4 00 FF F0 60 00 30 00 FA answer from slave,

(BASCOM-AVR version : 2.0.7.7 , Latest : 2.0.7.8 )

PeterM · Joined: 09 Jun 2008 Posts: 118

Ghitab

Bascom supports LIN/Uart routines, see attiny167.bas sample from the SAMPLES folder.

I am not sure if I missed something in the Datasheet (I use the M32M1 myself)
but the TX output pin you are using is PORTC.1 , the LIN TX and RX lines are
PORTD.3 (RX Line) and PORTD.4 (TX Line).

Ghitab · Joined: 25 Sep 2012 Posts: 10

Hi. thank's for answer. My attiny167.bas has only a uart example, can you please share your version that has lin example?
Portc.1 I use only for "nslp" pin of tja1020 controller, txlin and rxdlin are linked to pd3 and pd4 of atmega.

PeterM · Joined: 09 Jun 2008 Posts: 118

Ghitab

Sorry I may have missunderstood, I assumed on a LIN bus you talk to it the same as a UART.
Typically a UART/RS232 won't allow another Node to be connected on the same wire but LIN allows you to
connect to multiple nodes on the same wiring.

PeterM · Joined: 09 Jun 2008 Posts: 118

Ghitab

Here are some LIN/UART routines, I wreckon with some minor register changes
it should work as LIN or at least guide you.

Ghitab · Joined: 25 Sep 2012 Posts: 10

Thank you Peter. I manage to addapt your rutine's with small change's to my need. Very Happy

PeterM · Joined: 09 Jun 2008 Posts: 118

Ghitab

Maybe post a sample incase others are interested in experimenting with LIN?

Ghitab · Joined: 25 Sep 2012 Posts: 10

Here it is. Very Happy