detpic/i2clib.asm

   1 ;######################################################################
   2 ; i2clib.inc - I2C LIBRARY - IMPLEMENTATION
   3 ;
   4 ; See i2clib.asm for documentation of the interface to this file.
   5
   6  include /usr/share/gputils/header/p18f458.inc
   7  radix dec
   8  include ../iwjpictest/insn-aliases.inc
   9
  10 ;============================================================
  11 ; COMMON ADMINISTRATIVE ROUTINES
  12
  13                 udata_acs
  14 t               res     1
  15
  16                 code
  17
  18 ;--------------------
  19 i2cs_init
  20 ;       W               slave number            undefined
  21                 rcall   slave2addr2
  22                 mov_wf  SSPADD
  23                 mov_lw  0x16 ; !SSPEN, CKP(release), I2C 7-bit slave
  24                 mov_wf  SSPCON1
  25                 mov_lw  0x81 ; GCEN, SEN
  26                 mov_wf  SSPCON2
  27                 mov_lw  0x8 ; SMP(noslew), !CKE, !BF(empty)
  28                 mov_wf  SSPSTAT
  29                 bs_f    TRISB, 0
  30                 bs_f    TRISB, 1
  31                 bc_f    IPR1, SSPIP
  32                 bs_f    SSPCON1, SSPEN
  33                 bs_f    PIE1, SSPIE
  34                 return
  35
  36 ;--------------------
  37 i2cs_interrupt
  38                 bt_f_if0 PIR1, SSPIF
  39                 return
  40 ; We have an interrupt.  What are the possibilities ?
  41                 mov_ff  SSPSTAT, t
  42
  43 chkval macro mask, value, label
  44                 mov_fw  t
  45                 and_lw  mask
  46                 xor_lw  value
  47                 bra_z   label
  48                 endm
  49                         ; bits we want to check
  50                         ;  80  60  20    04    02  01
  51                         ;  SMP CKE D_A   R_W   UA  BF
  52                         ;  set clr data? read? clr full?
  53
  54                 chkval  0xe3, 0x81, got_addr
  55                 chkval  0xe7, 0xa1, got_data_write
  56                 chkval  0xe7, 0xa4, sent_data_read
  57
  58
  59
  60                 mov_fw  SSPSTAT
  61                 and_lw  0xe7 ; all except P and S
  62
  63                 xor_lw  0x80
  64                         ; bits which might sensibly be set
  65
  66 chkval_last equ 0
  67 chkval macro value, label
  68                 xor_lw  value ^ chkval_last
  69                 bra_z   label
  70 chkval_last equ value
  71                 endm
  72                 chkval  0x80 ;     addr  dunno
  73
  74                 mov_lw  0x8
  75
  76
  77                 bt_f_if0 DATA_ADDRESS, SSPSTAT
  78                 bra     data
  79
  80 slave2addr
  81 ; computes slave address in form suitable for use in i2c controller
  82 ; actual i2c slave address is (slave number) + 0b0001000
  83 ;       W               slave number            i2c address * 2
  84                 add_lw  0b0001000
  85                 rlc_w
  86                 return
  87
  88
  89
  90
  91  include i2clib.inc
  92  end