counter.asm

PIC16F628A芯片制作的频率计

;**************************************************************************
;                                                                         *
; File register usage                                                     *
;                                                                         *
;**************************************************************************


; RAM memory (general purpose registers, unfortunately not the same for PIC16F84 & PIC16F628)
;   in PIC16F628: RAM from 0x20..0x7F   (96 bytes, 0x20.. only accessable in Bank0)
;                          0xA0..0xEF   (another 80 bytes in Bank1)
;                          0x120..0x14F (another 48 bytes in Bank2)
;   0x0F0..0x0FF, 0x170..0x17F , 0x1F0..0x1FF are mapped to 0x70..0x7F (same in all banks)
;   So use 0x70..0x7F for context saving in the PIC16F628 and forget 0x0F0.. 0xNNN !
;
;  Note on the 32-bit integer arithmetics as used in this code:
;   - They begin with MOST SIGNIFICANT BYTE in memory, but...
;   - Every byte location has its own label here, which makes debugging
;     with Microchip's simulator much easier (point the mouse on the name
;     of a variable to see what I mean !)
;

tens_index     equ  0x27      ; index into the powers-of-ten table
divi           equ  0x28      ; power of ten (32 bits)
divi_hi        equ  0x28      ; same as 'divi' : HIGH byte
divi_mh        equ  0x29      ; MEDIUM HIGH byte
divi_ml        equ  0x2A      ; MEDIUM LOW  byte
divi_lo        equ  0x2B      ; LOW byte

timer0_old     equ  0x2C      ; previous reading from timer0 register

gatecnt_hi     equ  0x2D      ; 16-bit counter (msb first)
gatecnt_lo     equ  0x2E      ; 16-bit counter (lsb last)

bTemp          equ  0x2F      ; temporary 8-bit register, 
                              ; may be overwritten in ALL subroutines

freq           equ  0x30      ; frequency in binary (32 bits)....
freq_hi        equ  0x30      ; same location, begins with HIGH byte 
freq_mh        equ  0x31      ; ... medium high byte
freq_ml        equ  0x32      ; ... medium low byte
freq_lo        equ  0x33      ; ... low byte

freq2          equ  0x34      ; frequency too, copied for programming mode
freq2_hi       equ  0x34      ; same location, begins with HIGH byte 
freq2_mh       equ  0x35      ; ... medium high byte
freq2_ml       equ  0x36      ; ... medium low byte
freq2_lo       equ  0x37      ; ... low byte

foffs          equ  0x38      ; frequency too, copied for programming mode
foffs_hi       equ  0x38      ; same location, begins with HIGH byte 
foffs_mh       equ  0x39      ; ... medium high byte
foffs_ml       equ  0x3A      ; ... medium low byte
foffs_lo       equ  0x3B      ; ... low byte


menu_index     equ  0x3C      ; menu item for programming mode
menu_timer     equ  0x3D      ; used to detect how long a key was pressed

digits         equ  0x40      ; frequency as decimal digits (8 bytes)...
digit_0        equ  0x40      ; same location as MOST SIGNIFICANT digit, 10-MHz
digit_1        equ  0x41      ; usually the 1-MHz-digit
digit_2        equ  0x42      ; usually the 100-kHz-digit
digit_3        equ  0x43      ; usually the 10-kHz-digit 
digit_4        equ  0x44      ; usually the 1-kHz-digit
digit_5        equ  0x45      ; usually the 100-Hz-digit
digit_6        equ  0x46      ; usually the 10-Hz-digit
digit_7        equ  0x47      ; usually the 1-Hz-digit
digit_8        equ  0x48      ; must contain a blank character (or trailing zero)

display0       equ  0x49      ; display #0 data
display1       equ  0x4A      ; display #1 data
display2       equ  0x4B      ; display #2 data
display3       equ  0x4C      ; display #3 data
display4       equ  0x4D      ; display #4 data

disp_index     equ  0x4E      ; index of the enabled display (0 to 4 for 5-digit display)
disp_timer     equ  0x4F      ; display multiplex timer (5 bits)

adjust_shifts  equ  0x50      ; count of 'left shifts' to compensate prescaler+gate time

blinker        equ  0x51      ; prescaler for the flashing 1-kHz-dot

psave_timer    equ  0x52      ; timer for power-save mode (incremented every 0.25 seconds)
psave_freq_lo  equ  0x53      ; low-byte of frequency to detect changes for power-save mode
psave_flags    equ  0x54      ; power-saving flags with the following bits:
#define PSFLAG_ACTIVE psave_flags,0 ; clear:normal mode,  set:power-saving in action (display blanked)

options        equ  0x55      ; display options with the following flag-bits:
#define OPT_PWRSAVE options,0 ; clear:normal mode,  set:power-saving mode enabled

;**************************************************************************
;                                                                         *
; Macros (1)                                                              *
;                                                                         *
;**************************************************************************

eep_dw  macro value  ; a DOUBLEWORD split into 4 bytes in the PIC's DATA EEPROM
           de  (value>>.24), (value>>.16)&0xFF, (value>>8)&0xFF, value&0xFF
        endm


;**************************************************************************
;                                                                         *
; EEPROM memory  definitions                                              *
;                                                                         *
;**************************************************************************
  
  ;     for PIC16F84:   0x00..0x3F were valid EEPROM locations (64 byte)
  ;     for PIC16F628:  0x00..0x7F are valid EEPROM locations (128 byte)
#define EEPROM_ADR_FREQ_OFFSET  0x00  ; EEPROM location for frequency offset
#define EEPROM_ADR_STD_IF_TABLE 0x04  ; EEPROM location for standard IF table (4*4 byte)
#define EEPROM_ADR_OPTIONS      0x20  ; EEPROM location for "options" (flags)

; Initial contents of DATA EEPROM:
 org (0x2100+EEPROM_ADR_FREQ_OFFSET)  
    eep_dw   .0        ; [00..03] initial frequency offset = ZERO

 org (0x2100+EEPROM_ADR_STD_IF_TABLE)  ;  standard IF table ...
    eep_dw   .455000   ; [04..07] frequently used in old AM radios 
    eep_dw  .3999000   ; [08..0B] used in "Miss Mosquita" (DK1HE / DL QRP AG)
    eep_dw  .4194304   ; [0C..0F] used in other homebrew amateur radio receivers
    eep_dw  .4433619   ; [10..13] sometimes  used in homebrew amateur radio receivers
    eep_dw .10700000   ; [14..17] frequently used in old FM radios
                       ; [18..1F] reserved for other "preprogrammed" values

 org (0x2100+EEPROM_ADR_OPTIONS)
    de      .0         ; [20]     "options" (flags), cleared by default


;**************************************************************************
;                                                                         *
; More Macros                                                             *
;                                                                         *
;**************************************************************************


;--------------------------------------------------------------------------
; macros to implement lookup tables - these macros hide the PIC syntax
; used and make the source code more readable 
;   (YHF: CAUTION - BUT THESE MACROS HIDE SOME VERY NASTY PITFALLS . 
;         TABLE MUST NOT CROSS PAGE BORDER DUE TO 'ADDWF PCL, f' ! )
;--------------------------------------------------------------------------

cquad  macro value
          retlw value>>.24              ; high byte
          retlw (value>>.16)&0xFF       ; middle-high byte
          retlw (value>>8)&0xFF         ; middle-low  byte
          retlw value&0xFF              ; low byte
       endm

table  macro label              ; define lookup table

label     addwf PCL,f  ; caution: this is 'PCL' only, cannot add to the full 'PC' in a PIC !
       endm


;--------------------------------------------------------------------------
; add with carry - adds the w register and the carry flag to the file
; register reg, returns the result in <reg> with the carry flag set if overflow
;--------------------------------------------------------------------------

addcwf    macro reg

          local add1,add2

          bnc add1                      ; branch if no carry set

          addwf reg , f                 ; add byte

          incf reg , f                  ; add carry
          skpnz
          setc

          goto add2

add1      addwf reg,f                   ; add byte

add2
          endm


;--------------------------------------------------------------------------
; subtract with "no-carry" - subtracts the w register and the no-carry flag
; from the file register reg, returns the result in reg with the no carry flag
; set if underflow
;--------------------------------------------------------------------------

subncwf   macro reg

          local sub1,sub2

          bc sub1                       ; branch if carry set
          subwf reg, f                  ; subtract byte
          skpnz                         ; subtract no carry
          clrc
          decf reg , f
          goto sub2
sub1      subwf reg , f                 ; subtract byte
sub2
          endm


;--------------------------------------------------------------------------
; MACRO to perform 32-bit addition - adds the four bytes at op2 to the
; three bytes at op1 (most significant bytes first), returns the result in
; op1 with op2 unchanged and the carry flag set if overflow
;--------------------------------------------------------------------------

add32     macro op1,op2                 ; op1 := op1 + op2

          movfw op2+3                   ; add low byte        (bits 7...0)
          addwf op1+3,f

          movfw op2+2                   ; add middle-low byte (bits 15..8)
          addcwf op1+2

          movfw op2+1                   ; add middle-high byte (bits 23...16)
          addcwf op1+1

          movfw op2+0                   ; add high byte       (bits 31...24) 
          addcwf op1+0

          endm


;--------------------------------------------------------------------------
; MACRO to perform 32-bit subtraction - subtracts the four bytes at op2
; from the four bytes at op1 (most significant bytes first), returns the
; result in op1 with op2 unchanged and the no carry flag set if underflow
;--------------------------------------------------------------------------

sub32     macro op1,op2                 ; op1 := op1 - op2

          movfw op2+3                   ; subtract low byte 
          subwf op1+3 , f

          movfw op2+2                   ; subtract middle low byte
          subncwf op1+2

          movfw op2+1                   ; subtract middle high byte
          subncwf op1+1

          movfw op2+0                   ; subtract high byte
          subncwf op1+0

          endm


;--------------------------------------------------------------------------
; MACRO to negate a 32-bit value  (  op := 0 - op ) .