cebpic/send-serial.asm

   1 ; pin 21 (per-pic-led, RD2/PSP2/C1IN) states: high H = green, low L = red, float Z = black
   2
   3         include         /usr/share/gputils/header/p18f458.inc
   4         radix           dec
   5
   6 clock equ mclock
   7         include         ../iwjpictest/clockvaries.inc
   8
   9         code
  10 start
  11 ; initial config
  12         bcf     TXSTA,6,0       ; p181, set 8-bit mode
  13         bsf     TXSTA,5,0       ; transmit enable
  14         bcf     TXSTA,4,0       ; asynchronous mode
  15         bsc_txsta_brgh          ; set high or low baud rate
  16         bsf     RCSTA,7,0       ; serial port enable (p182)
  17
  18 ; set SPBRG to get correct baud rate
  19         movlw_movwf_spbrg
  20
  21         call    initialiseascii
  22
  23 main
  24         movff   00h,TXREG       ; move 00h to transmit buffer (ascii s)
  25         call    waitfortsr
  26         movff   01h,TXREG       ; move 01h to transmit buffer (ascii q)
  27         call    waitfortsr
  28         movff   02h,TXREG       ; move 02h to transmit buffer (ascii o)
  29         call    waitfortsr
  30         movff   02h,TXREG       ; move 02h to transmit buffer (ascii o)
  31         call    waitfortsr
  32         movff   03h,TXREG       ; move 03h to transmit buffer (ascii k)
  33         call    waitfortsr
  34         movff   04h,TXREG       ; move 04h to transmit buffer (ascii SPACE)
  35         call    waitfortsr
  36         goto    main
  37
  38
  39 waitfortsr
  40         btfss   TXSTA,1,0       ; check whether TRMT is set (i.e. TSR is empty)
  41         bra     waitfortsr
  42         return
  43
  44
  45 initialiseascii ; set up ascii letter bytes
  46
  47 ; there must be a faster way to do this...
  48
  49         clrf    00h,0   ; clear data registers
  50         clrf    01h,0
  51         clrf    02h,0
  52         clrf    03h,0
  53         clrf    04h,0
  54
  55         bsf     00h,6,0 ; set 00h to be ascii s
  56         bsf     00h,5,0
  57         bsf     00h,4,0
  58         bsf     00h,1,0
  59         bsf     00h,0,0
  60
  61         bsf     01h,6,0 ; set 01h to be ascii q
  62         bsf     01h,5,0
  63         bsf     01h,4,0
  64         bsf     01h,0,0
  65
  66         bsf     02h,6,0 ; set 01h to be ascii o
  67         bsf     02h,5,0
  68         bsf     02h,3,0
  69         bsf     02h,2,0
  70         bsf     02h,1,0
  71         bsf     02h,0,0
  72
  73         bsf     03h,6,0 ; set 03h to be ascii k
  74         bsf     03h,5,0
  75         bsf     03h,3,0
  76         bsf     03h,1,0
  77         bsf     03h,0,0
  78
  79         bsf     04h,5,0 ; set 04h to be ascii _
  80
  81         return
  82
  83         end