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00001 ;;; LEDDRVR2.ASM
00002 ;;; Copyright (c) 2002, TundraWare Inc., All Rights Reserved
00003 ;;;
00004 ;;; Program to drive homemade LED display board
00005 ;;;
00006 ;;; $Id: leddrvr2.asm,v 2.4 2002/05/02 19:25:21 tundra Exp tundra $
00007
00008
00009 list p=16F84A
00010 include <P16F84A.INC>
00001 LIST
00002 ; P16F84A.INC Standard Header File, Version 2.00 Microchip Technology, Inc.
00134 LIST
00011
00012 errorlevel -302 ;suppress bank selection messages
2007 3FF1 00013 __config 3ff1h ;xt osc, WDT off
2000 0001 0002 0003 00014 __idlocs 1234
0004
00015
00016 ;;;;;;;;;;
00017 ;;; Device Constants
00018 ;;;;;;;;;;
00019
00000000 00020 tmr2 equ 00H ; TMR0 prescaler constants
00000001 00021 tmr4 equ 01H
00000002 00022 tmr8 equ 02H
00000003 00023 tmr16 equ 03H
00000004 00024 tmr32 equ 04H
00000005 00025 tmr64 equ 05H
00000006 00026 tmr128 equ 06H
00000007 00027 tmr256 equ 07H
00028
00029
00030 ;;;;;;;;;;
00031 ;;; Circuit Constants
00032 ;;;;;;;;;;
00033
00000008 00034 num_led equ 8 ; total number of LEDs
00000000 00035 led_clk equ 0 ; bit used to clock led selection
00000001 00036 led_dat equ 1 ; bit used for led selection data
00000002 00037 led_strobe equ 2
00000005 00038 led_ctrl equ PORTA ; intf to LED control shift registers
00039
00040
00041 ;;;;;;;;;;
00042 ;;; Program Contants
00043 ;;;;;;;;;;
00044
00045 ;;; TMR0 related stuff
00046 ;;;
00047 ;;; With a 4MHz clock, the basic cycle type is 1/4 this or 1us.
00048 ;;; The TMR0 interrupt interrupt interval is thus:
00049 ;;;
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00050 ;;; 1us * prescaler factor * tmr0_count
00051 ;;;
00052
00053 ;;; TMR0 interrupt every 1ms
00054
000000FA 00055 interval equ D'250' ; basic (TMR0 interval/4) in us
00000006 00056 tmr0_count equ D'256'-interval ; set for 250us interrupt interval
00000001 00057 tmr0_pre equ tmr4 ; prescaler factor
00058
00059
00060 ;;; wait delays: delay time = value(s) below * TMR0 interrupt rate
00061
00000005 00062 count_delay equ D'5' ; 5ms delay between counts
00063
00064
00065 ;;;;;;;;;;
00066 ;;; Register File Assignments
00067 ;;;;;;;;;;
00068
00069 CBLOCK 0cH
0000000C 00070 _fsr ; context save area
0000000D 00071 _pclath
0000000E 00072 _status
0000000F 00073 _w
00074
00000010 00075 dsply_val:(num_led/2) ; array of values to display
00076 ; 2 LEDs per byte
00077
00000014 00078 current_led ; currently displayed LED
00079 ; 0 <= current_led < num_led
00080
00000015 00081 led_seg ; segment to illuminate
00000016 00082 led_sel ; led selection pattern
00083
00000017 00084 wait_count ; time delay counter variable
00000018 00085 temp ; temp storage during calculation
00086 ENDC
00087
00088
00089 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
00090
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00091 PAGE
00092 ;;;;;;;;;;
00093 ;;; Power-On Entry Point
00094 ;;;;;;;;;;
00095
0000 00096 org 00H
00097
0000 2825 00098 goto main
00099
00100 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
00101
00102 ;;;;;;;;;;
00103 ;;; Interrupt Handler
00104 ;;;;;;;;;;
00105
0004 00106 org 04H
00107
0004 008F 00108 movwf _w ; save context
0005 0803 00109 movfw STATUS
0006 1303 00110 bcf STATUS,RP1
0007 1283 00111 bcf STATUS,RP0
0008 008E 00112 movwf _status
0009 0804 00113 movfw FSR
000A 008C 00114 movwf _fsr
000B 080A 00115 movfw PCLATH
000C 008D 00116 movwf _pclath
000D 018A 00117 clrf PCLATH
00118
00119 ; Figure out who interrupted and service it
00120
000E 190B 00121 btfsc INTCON,T0IF ; did we get a TMR0 interrupt?
000F 2811 00122 goto svc_tmr0 ; yup
0010 281C 00123 goto restore_context ; nope
00124
00125 ; TMR0 ISR
0011 00126 svc_tmr0:
0011 110B 00127 bcf INTCON,T0IF ; clear the interrupt condition
0012 3006 00128 movlw tmr0_count ; prime the counter
0013 0081 00129 movwf TMR0
0014 018B 00130 clrf INTCON ; Enable *just* this interrupt
0015 168B 00131 bsf INTCON,T0IE ; to maintain timing accuracy
0016 178B 00132 bsf INTCON,GIE
00133
00134 ; Update the wait timer if it is in use
00135 ; Only do this on TMR0 interrupts so timing is predictable
00136
0017 0817 00137 movfw wait_count
0018 1D03 00138 btfss STATUS,Z ; non-zero count means 'in use'
0019 0397 00139 decf wait_count,F ; decrement current count
00140 ; not in-use, fall through to next code
00141
001A 2044 00142 call display_led ; then display it
001B 281C 00143 goto restore_context ; goto here (instead of just falling
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00144 ; through) allows other ISRs
00145 ; to later be added immediately
00146 ; following
00147
001C 00148 restore_context:
001C 080D 00149 movfw _pclath ; restore entry context
001D 008A 00150 movwf PCLATH
001E 080C 00151 movfw _fsr
001F 0084 00152 movwf FSR
0020 080E 00153 movfw _status
0021 0083 00154 movwf STATUS
0022 0E8F 00155 swapf _w,F ; get W back w/o changing Z flag
0023 0E0F 00156 swapf _w,W
00157
0024 0009 00158 retfie ; all done
00159
00160 ;;; End of interrupt handler
00161
00162 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
00163
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00164 PAGE
00165 ;;;;;;;;;;
00166 ;;; Main program logic
00167 ;;;;;;;;;;
00168
0025 00169 main:
0025 2083 00170 call init ; initialize the system
0026 00171 run:
0026 2076 00172 call incr_count
0027 3005 00173 movlw count_delay
0028 207E 00174 call wait ; slow down displayed count
0029 2826 00175 goto run
00176
00177 ;;; End of main logic
00178
00179
00180 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
00181
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00182 PAGE
00183 ;;;;;;;;;;
00184 ;;; Data & Tables
00185 ;;;;;;;;;;
00186
00187 ;;;;;;;;;;
00188 ;;; Hex Digit-to-Segment lookup table
00189 ;;;;;;;;;;
00190
00191
002A 0782 00192 hex_7seg addwf PCL,F
002B 343F 00193 DT 03fH ; 0
002C 3406 00194 DT 006H ; 1
002D 345B 00195 DT 05bH ; 2
002E 344F 00196 DT 04fH ; 3
002F 3466 00197 DT 066H ; 4
0030 346D 00198 DT 06dH ; 5
0031 347D 00199 DT 07dH ; 6
0032 3407 00200 DT 007H ; 7
0033 347F 00201 DT 07fH ; 8
0034 3467 00202 DT 067H ; 9
0035 3477 00203 DT 077H ; A
0036 347C 00204 DT 07cH ; B
0037 3458 00205 DT 058H ; C
0038 345E 00206 DT 05eH ; D
0039 3479 00207 DT 079H ; E
003A 3471 00208 DT 071H ; F
00209
00210
00211 ;;;;;;;;;;
00212 ;;; Table used to translate LED position to equivalent led_sel
00213 ;;; bit pattern for that LED. It is assumed that any routine using
00214 ;;; this table will properly preserve higher-order bits not needed for
00215 ;;; LED selection.
00216 ;;;;;;;;;;
00217
003B 00218 led_lookup:
003B 0782 00219 addwf PCL,F
003C 3401 00220 DT 01H ; LED0 == LSD
003D 3402 00221 DT 02H ; LED1
003E 3404 00222 DT 04H ; LED2
003F 3408 00223 DT 08H ; LED3
0040 3410 00224 DT 10H ; LED4
0041 3420 00225 DT 20H ; LED5
0042 3440 00226 DT 40H ; LED6
0043 3480 00227 DT 80H ; LED7
00228
00229
00230 ;;; End of 'led_lookup'
00231
00232
00233 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
00234
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00235 PAGE
00236 ;;;;;;;;;;
00237 ;;; Supporting Subroutines
00238 ;;;;;;;;;;
00239
00240
00241 ;;;;;;;;;;
00242 ;;; Display LEDs, one per call, from MSD->LSD
00243 ;;; This effectively multiplexes across all the LEDs
00244 ;;; when called repeatedly.
00245 ;;;;;;;;;;
00246
0044 00247 display_led:
00248 ; compute and set the segments to display for this digit
00249 ; this logic only works if 'num_led' is *even* !!!!
00250
0044 0814 00251 movfw current_led ; convert current_led into an
0045 0084 00252 movwf FSR ; offset from base of display storage
0046 1003 00253 bcf STATUS,C ; don't rotate C into calc below
0047 0C84 00254 rrf FSR,F ; /2 - two digits stored in each byte
0048 3010 00255 movlw dsply_val ; base of array containing display vals
0049 0784 00256 addwf FSR,F ; point to desired value
004A 0800 00257 movfw INDF ; and get contents
004B 0098 00258 movwf temp ; store temporarily
004C 1814 00259 btfsc current_led,0 ; even or odd nibble
004D 0E98 00260 swapf temp,F ; odd==hi nibble -> low nibble
004E 0818 00261 movfw temp ; get it
004F 390F 00262 andlw 0fH ; mask off high nibble
0050 202A 00263 call hex_7seg ; convert to equivalent seg pattern
0051 0095 00264 movwf led_seg ; and save for shift out
00265
00266 ; select the corresponding LED
00267
0052 0814 00268 movfw current_led ; get the bit pattern that selects
0053 203B 00269 call led_lookup ; desired LED
0054 0096 00270 movwf led_sel ; and save for shift out
00271
00272 ; now shift the current control bits out and latch them
00273
0055 205D 00274 call led_wrt
00275
00276 ; determine next LED to display
00277
0056 0814 00278 movfw current_led ; get LED just displayed
0057 1D03 00279 btfss STATUS,Z ; was it the LSD?
0058 285B 00280 goto set_next ; nope
0059 3008 00281 movlw num_led ; yup, start again w/MSD
005A 0094 00282 movwf current_led
005B 00283 set_next:
005B 0394 00284 decf current_led,F ; pickup next digit to right
005C 0008 00285 return
00286
00287 ;;; End of 'display_led'
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00288
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00289 PAGE
00290 ;;;;;;;;;;
00291 ;;; Shift the control bits in 'led_seg' and 'led_sel' into the
00292 ;;; LED controller shift registers.
00293 ;;;;;;;;;;
00294
005D 00295 led_wrt:
00296 ; first shift out LED select pattern LSB->MSB
00297
005D 3008 00298 movlw 08H ; do this for all 8 bits
005E 00299 shift_sel:
005E 1085 00300 bcf led_ctrl,led_dat ; assume output 0
005F 1C16 00301 btfss led_sel,0
0060 2862 00302 goto clk_sel ; shift out a 0
0061 1485 00303 bsf led_ctrl,led_dat ; shift out a 1
0062 00304 clk_sel:
0062 1405 00305 bsf led_ctrl,led_clk ; clock it into the
0063 1005 00306 bcf led_ctrl,led_clk ; shift register
0064 0C96 00307 rrf led_sel,F ; pickup the next bit
0065 3EFF 00308 addlw -1 ; decrement repeat count
0066 1D03 00309 btfss STATUS,Z
0067 285E 00310 goto shift_sel
00311
00312 ; then shift out segment select pattern 'a'->'dp'
00313
0068 3008 00314 movlw 08H ; do this for all 8 bits
0069 00315 shift_seg:
0069 1085 00316 bcf led_ctrl,led_dat ; assume output 0
006A 1C15 00317 btfss led_seg,0
006B 286D 00318 goto clk_seg ; shift out a 0
006C 1485 00319 bsf led_ctrl,led_dat ; shift out a 1
006D 00320 clk_seg:
006D 1405 00321 bsf led_ctrl,led_clk ; clock it into the
006E 1005 00322 bcf led_ctrl,led_clk ; shift register
006F 0C95 00323 rrf led_seg,F ; pickup the next bit
0070 3EFF 00324 addlw -1 ; decrement repeat count
0071 1D03 00325 btfss STATUS,Z
0072 2869 00326 goto shift_seg
00327
00328 ; now strobe to output latch
00329
0073 1505 00330 bsf led_ctrl,led_strobe ; propagate changes
0074 1105 00331 bcf led_ctrl,led_strobe ; latch changes
00332
0075 0008 00333 return
00334
00335 ;;; End of 'led_wrt'
00336
00337
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00338 PAGE
00339 ;;;;;;;;;;
00340 ;;; Increment current count by 1
00341 ;;;;;;;;;;
00342
0076 00343 incr_count:
0076 0F90 00344 incfsz dsply_val,F ; count up 8 digits worth
0077 0008 00345 return
0078 0F91 00346 incfsz dsply_val+1,F
0079 0008 00347 return
007A 0F92 00348 incfsz dsply_val+2,F
007B 0008 00349 return
007C 0A93 00350 incf dsply_val+3,F
007D 0008 00351 return
00352
00353 ;;; End of 'incr_count'
00354
00355
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00356 PAGE
00357 ;;;;;;;;;;
00358 ;;; Kill time - Outer loop constant passed in W.
00359 ;;;;;;;;;;
00360
007E 00361 wait:
007E 0097 00362 movwf wait_count ; this will be decremented in ISR
007F 00363 loop:
007F 0817 00364 movfw wait_count ; get current count
0080 1D03 00365 btfss STATUS,Z ; see if we counted all the way down
0081 287F 00366 goto loop ; not done, keep waiting
0082 0008 00367 return ; all done
00368
00369 ;;; End of 'wait'
00370
00371
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00372 PAGE
00373 ;;;;;;;;;;
00374 ;;; Initialize hardware and software at startup as needed.
00375 ;;; Returns with register bank 0 selected.
00376 ;;;;;;;;;;
00377
0083 00378 init:
0083 018B 00379 clrf INTCON ; all interrupts off, flags cleared
00380
00381 ; setup control registers
00382
0084 168B 00383 bsf INTCON,T0IE ; unmask TMR0 interrupts
0085 1683 00384 bsf STATUS,RP0 ; select register bank 1
0086 0185 00385 clrf TRISA ; set PORTA to all outputs
0087 0186 00386 clrf TRISB ; set PORTB to all outputs
0088 0181 00387 clrf OPTION_REG ; TMR0 selected w/ internal clock
00388 ; don't care about RBPU, INTEDG
0089 3001 00389 movlw tmr0_pre ; set TMR0 prescaler value
008A 0481 00390 iorwf OPTION_REG,F
008B 1283 00391 bcf STATUS,RP0 ; select register bank 0
00392
00393 ; setup program variables
00394
008C 3010 00395 movlw dsply_val ; initialize count storage to 0
008D 0084 00396 movwf FSR ; this logic only works if
008E 3004 00397 movlw num_led/2 ; if 'num_led' is *even* !!!
008F 00398 zero_count:
008F 0180 00399 clrf INDF ; zero the storage location
0090 3EFF 00400 addlw -1 ; decrement loop count
0091 1903 00401 btfsc STATUS,Z ; when zero, we're done
0092 2895 00402 goto prime_counter ; we're done
0093 0A84 00403 incf FSR,F ; point to next storage location
0094 288F 00404 goto zero_count ; and do it again
00405
0095 00406 prime_counter:
0095 3006 00407 movlw tmr0_count ; prime the counter
0096 0081 00408 movwf TMR0
00409
0097 3007 00410 movlw num_led-1 ; start displaying with MSD
0098 0094 00411 movwf current_led
00412
0099 1105 00413 bcf led_ctrl,led_strobe ; initialize control bits
009A 1005 00414 bcf led_ctrl,led_clk
00415
009B 0195 00416 clrf led_seg ; all segments off
009C 0196 00417 clrf led_sel ; all LEDs off
009D 205D 00418 call led_wrt ; write out the changes
00419
009E 178B 00420 bsf INTCON,GIE ; enable unmasked interrupts
009F 0008 00421 return
00422
00423 ;;; End of 'init'
00424
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00425
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00426 PAGE
00427 ;;;;;;;;;;
00428 ;;; EEPROM Contents
00429 ;;;;;;;;;;
00430
2100 00431 org 2100h
00432
2100 0043 006F 0070 00433 DE "Copyright 2002, TundraWare Inc. All Rights Reserved."
0079 0072 0069
0067 0068 0074
0020 0032 0030
0030 0032 002C
0020 0054 0075
006E 0064 0072
0061 0057 0061
0072 0065 0020
0049 006E 0063
002E 0020 0020
0041 006C 006C
0020 0052 0069
0067 0068 0074
0073 0020 0052
0065 0073 0065
0072 007
00434 END
MPASM 03.00 Released LEDDRVR2.ASM 5-2-2002 19:27:08 PAGE 15
SYMBOL TABLE
LABEL VALUE
C 00000000
DC 00000001
EEADR 00000009
EECON1 00000088
EECON2 00000089
EEDATA 00000008
EEIE 00000006
EEIF 00000004
F 00000001
FSR 00000004
GIE 00000007
INCFILES ../include
INDF 00000000
INTCON 0000000B
INTE 00000004
INTEDG 00000006
INTF 00000001
IRP 00000007
NOT_PD 00000003
NOT_RBPU 00000007
NOT_TO 00000004
OPTION_REG 00000081
PCL 00000002
PCLATH 0000000A
PORTA 00000005
PORTB 00000006
PS0 00000000
PS1 00000001
PS2 00000002
PSA 00000003
RBIE 00000003
RBIF 00000000
RD 00000000
RP0 00000005
RP1 00000006
STATUS 00000003
T0CS 00000005
T0IE 00000005
T0IF 00000002
T0SE 00000004
TMR0 00000001
TRISA 00000085
TRISB 00000086
W 00000000
WR 00000001
WREN 00000002
WRERR 00000003
Z 00000002
_CP_OFF 00003FFF
_CP_ON 0000000F
_HS_OSC 00003FFE
_LP_OSC 00003FFC
_PWRTE_OFF 00003FFF
MPASM 03.00 Released LEDDRVR2.ASM 5-2-2002 19:27:08 PAGE 16
SYMBOL TABLE
LABEL VALUE
_PWRTE_ON 00003FF7
_RC_OSC 00003FFF
_WDT_OFF 00003FFB
_WDT_ON 00003FFF
_XT_OSC 00003FFD
__16F84A 00000001
_fsr 0000000C
_pclath 0000000D
_status 0000000E
_w 0000000F
clk_seg 0000006D
clk_sel 00000062
count_delay 00000005
current_led 00000014
display_led 00000044
dsply_val 00000010
hex_7seg 0000002A
incr_count 00000076
init 00000083
interval 000000FA
led_clk 00000000
led_ctrl 00000005
led_dat 00000001
led_lookup 0000003B
led_seg 00000015
led_sel 00000016
led_strobe 00000002
led_wrt 0000005D
loop 0000007F
main 00000025
num_led 00000008
prime_counter 00000095
restore_context 0000001C
run 00000026
set_next 0000005B
shift_seg 00000069
shift_sel 0000005E
svc_tmr0 00000011
temp 00000018
tmr0_count 00000006
tmr0_pre 00000001
tmr128 00000006
tmr16 00000003
tmr2 00000000
tmr256 00000007
tmr32 00000004
tmr4 00000001
tmr64 00000005
tmr8 00000002
wait 0000007E
wait_count 00000017
zero_count 0000008F
MPASM 03.00 Released LEDDRVR2.ASM 5-2-2002 19:27:08 PAGE 17
MEMORY USAGE MAP ('X' = Used, '-' = Unused)
0000 : X---XXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX
0040 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX
0080 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX ---------------- ----------------
2000 : XXXX---X-------- ---------------- ---------------- ----------------
2100 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXX-----------
All other memory blocks unused.
Program Memory Words Used: 157
Program Memory Words Free: 867
Errors : 0
Warnings : 0 reported, 0 suppressed
Messages : 0 reported, 4 suppressed
