4 bit 7 segment display with two 74HC595

[louislouis]

It’s not bad except you don’t need 4 copies of the same lookup table. That should be a subroutine.
If possible, there should be four identical subroutines that you feed each digit to.

You’d normally do the display multiplex in the main program, and only use the interrupt to set a flag
that is being watched by the main program to know when a second, or whatever period ticks over.
The interrupt handler should be the smaller routine.

Hello Art,

something like this:

'****************************************************************
'*  Name    : 4 bit 7 segment display                           *
'*  Author  : LouisLouis                                        *
'*  Notice  : Copyright (c) 2018                                *
'*          : All Rights Reserved                               *
'*  Date    : 18. 2. 2018                                       *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*  MCU     : PIC 12F1840                                       *
'****************************************************************

#CONFIG
  __config _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON
  __config _CONFIG2, _WRT_OFF & _PLLEN_ON & _STVREN_ON & _BORV_19 & _LVP_OFF
#ENDCONFIG

DEFINE OSC 32            ; Use internal clock 
OSCCON = %01110000
CLKRCON = 0

Include "modedefs.bas"
INCLUDE "DT_INTS-14.bas" ; Base Interrupt System
INCLUDE "ReEnterPBP.bas" ; Include if using PBP interrupts

TRISA = %000000
ANSELA = %0000  
OPTION_REG.7=0           ; Enable internal pull-ups

LPIN var porta.2         ; Latch
DPIN var porta.4         ; Data
CPIN var porta.5         ; Clock

segment var byte
value var word
place var byte[4]
ones var word
tens var word
hundreds var word
thousands var word

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
    INT_Handler TMR1_INT, _DISP, PBP, yes
  endm
  INT_CREATE ; Creates the interrupt processor
ENDASM

@ INT_ENABLE TMR1_INT ; enable Timer 1 interrupts
T1CON = $1

;---[show HELO for 0,5sec.]----------------------------------------------------- 
intro:
segment=12
gosub look
ones=segment
segment=11
gosub look
tens=segment
segment=10
gosub look
hundreds=segment
segment=13
gosub look
thousands=segment
pause 500

;---[simple counter 0 - to 9999]------------------------------------------------
Main:
for value = 0 to 9999
gosub setdisp
pause 10
next value
value = 0
GOTO Main

setdisp:
segment = value//10
gosub look
ones=segment            ; extract ones

segment =  value/10 
segment = segment//10
gosub look
tens=segment            ; extract tens

segment =   value/100
segment = segment//10
gosub look
hundreds=segment        ; extract hundreds

segment = value/1000
gosub look
thousands=segment       ; extract thousands

;---[7 segment pattern 0123456789 and letters H E L O]--------------------------
look:                 
lookup segment, [%11000000,%11111001,%10100100,%10110000,%10011001,%10010010,%10000010,%11111000,%10000000,%10010000,%10000110,%11000111,%11000000,%10001001],segment
return
return

;---[TMR1 - interrupt handler]--------------------------------------------------
DISP:
T1CON.0 = 0                ; stop timer
TMR1H = %11111100
TMR1L = %00011111
T1CON.0 = 1                ; restart timer

;---[multiplex and show]--------------------------------------------------------  
LOW  LPIN
Shiftout DPIN, CPIN, MSBFIRST,[ones,%0001] 
high lpin
pause 2
LOW  LPIN
Shiftout DPIN, CPIN, MSBFIRST,[tens,%0010] 
high lpin
pause 2
LOW  LPIN
Shiftout DPIN, CPIN, MSBFIRST,[hundreds,%0100] 
high lpin
pause 2
LOW  LPIN
Shiftout DPIN, CPIN, MSBFIRST,[thousands,%1000] 
high lpin
@ INT_RETURN

It is a bit slower, but now I can display digits and letters.
Otherwise, I don't think this is a more efficient and elegant code, it must be a better way.

[mpgmike]

At the bottom of look: you have RETURN listed twice.

You turn TMR1 Off (T1CON = 0) in your Disp: Interrupt Handler but I don't see where you turn it back on.

"segment = value/1000
gosub look
thousands=segment ; extract thousands"

Leads right into your look: Interrupt Handler. If that was to be a subroutine, you need that extra RETURN relocated to the end of that grouping.

[louislouis]

At the bottom of look: you have RETURN listed twice.

yes I forgot to delete one return, but it doesn't matter.

You turn TMR1 Off (T1CON = 0) in your Disp: Interrupt Handler but I don't see where you turn it back on.

Here: T1CON.0 = 1 ; restart timer

;---[TMR1 - interrupt handler]--------------------------------------------------
DISP:
T1CON.0 = 0                ; stop timer
TMR1H = %11111100
TMR1L = %00011111
T1CON.0 = 1                ; restart timer

Both codes which I posted works fine. I'm looking for more professional (easier, better, more skilled) example to do this.

[Art]

One of many ways to pull your counter value apart in BASIC is using DIG.
Copy the counter to another buffer so it stays safe.
This may be rough, and won't compile straight up.

destructobuffer = countervalue

FOR loopcounter = 0 TO 3
digitvalue = destructobuffer DIG 0
print digitvalue
shift out a digit
delay for digit (if you must)
destructobuffer = destructobuffer / 10
NEXT loopcounter

[mpgmike]

Here: T1CON.0 = 1 ; restart timer

TMR1H = %11111100
TMR1L = %00011111
T1CON.0 = 1                ; restart timer

Most of the data sheets say that when you write to the TMRxH/L, you must declare the entire TxCON SFR. I personally have made a practice of using T1CON = %xxxxxxxx instead of isolating a single bit in the TxCON register after preloading the TMRx register. I actually had a bug that I couldn't figure out for the longest time. When I wrote to the entire Timer Register instead of just a single 1/0 bit, it started working. If it works now, you could leave it as is. If you have issues, try what I suggested here.

[tumbleweed]

Most of the data sheets say that when you write to the TMRxH/L, you must declare the entire TxCON SFR

Could you point to an example of that?

[richard]

Could you point to an example of that?

me too
I have never had to do that and can find no mention of that short coming anywhere


anyways here is my take on the 7 seg display
if you have a chip with mssp why waste time and code space when the hardware can do it for you

I cheated a bit and did it in asm for speed and size gains
no nasty pauses , all gone
my displays are common anode so the data is inverted see comments

'****************************************************************
'*  Name    : 4 bit 7 segment display                           *
'*  Author  : RICHARD                                           *
'*  Notice  :                                                   *
'*          :                                                   *
'*  Date    : 18. 2. 2018                                       *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*  MCU     : PIC 16F1825 @32MHZ                                *
'****************************************************************
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_OFF & _LVP_OFF
#ENDCONFIG

 goto overasm
 asm
timer1  = TMR1L 
 
seg_val       
    addwf   PCL, F                  
    retlw  0xc0;0B11000000     0  
    retlw  0xf9;0B11111001     1     
    retlw  0xa4;0B10100100     2
    retlw  0xb0;0B10110000     3
    retlw  0x99;0B10011001     4
    retlw  0x92;0B10010010     5                     
    retlw  0x82;0B10000010     6
    retlw  0xf8;0B11111000     7
    retlw  0x80;0B10000000     8  
    retlw  0x90;0B10010000     9
 endasm

 overasm:
DEFINE OSC 32            ; Use internal clock 
ANSELC=0
SSP1CON1=$22  
SSP1STAT=$40
OSCCON=$f0

INCLUDE "DT_INTS-14.bas" ; Base Interrupt System

TRISC = %11101010
LPIN var portc.4         ; Latch
DPIN var portc.2         ; Data  SDO
CPIN var portc.0         ; Clock SCK
segment var byte
value var word
d_index var byte
buff var byte[5]
tmp var byte             
d_pointer      var byte  
timer1 var word ext
timer1_reload con    1543      ;8mS
ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
    INT_Handler TMR1_INT, _DISP, ASM, yes
  endm
  INT_CREATE ; Creates the interrupt processor
ENDASM
@ INT_ENABLE TMR1_INT ; enable Timer 1 interrupts
T1CON = $1
d_index=0
;---[simple counter 0 - to 9999]------------------------------------------------ 
Main:
for value = 0 to 9999
arraywrite buff ,[dec4 value]
pause 100
next value
value = 0
GOTO Main
;---[TMR1 - interrupt handler]--------------------------------------------------
DISP:
asm
    MOVE?CT 0, T1CON, TMR1ON ; 1 stop timer
    MOVLW LOW(_timer1_reload) ; 1 Add TimerReload to the 
    ADDWF TMR1L,F ; 1 value in Timer1
    BTFSC STATUS,C ; 1/2
    INCF TMR1H,F ; 1
    MOVLW HIGH(_timer1_reload) ; 1
    ADDWF TMR1H,F ; 1
    MOVE?CT 1, T1CON, TMR1ON ; 1 start timer
    MOVE?CB  high _buff, FSR0H         ;load highbyte 
    MOVE?CB  low  _buff, FSR0L         ;load low byte
    MOVE?BA  _d_index  
    ADDWF  FSR0L,F
    MOVLW 0X30
    SUBWF INDF0,W
    L?CALL seg_val
    MOVE?AB _segment
    MOVE?BB  _d_index ,_tmp
    BANKSEL   _tmp
    MOVLW 1
    ADDWF  _tmp,F
    BANKSEL   _d_pointer
    CLRF _d_pointer
    BSF STATUS ,C
N_BIT 
    BANKSEL   _d_pointer
    RLF    _d_pointer,F
    BCF STATUS ,C
    BANKSEL   _tmp
    DECFSZ  _tmp,F
    GOTO N_BIT 
    MOVLW 1
    BANKSEL  _d_index
    ADDWF  _d_index,F
    MOVLW 3 
    ANDWF  _d_index,F
    BANKSEL  LATC
    BCF LATC ,4
    BANKSEL PIR1
    BCF     PIR1,3 
    BANKSEL  _segment
    COMF    _segment,W  ;COMMENT USED TO INVERT DATA FOR COMMON ANODE DISPLAY
    BANKSEL SSP1BUF
    movwf   SSP1BUF
    BANKSEL PIR1
    BTFSs   PIR1,3
    GOTO    $-1
    BANKSEL  _d_pointer
    COMF    _d_pointer,W ; ;COMMENT USED FOR COMMON ANODE DISPLAY
    BANKSEL PIR1
    BCF     PIR1,3 
    BANKSEL SSP1BUF
    movwf   SSP1BUF
    BANKSEL PIR1
    BTFSs   PIR1,3
    GOTO    $-1
    BANKSEL  LATC
    BSF LATC ,4
    BANKSEL 0
    INT_RETURN
endasm

[mpgmike]

OK, looked through a K50 and 16F1619 Data Sheet for that note or catch phrase indicating a full write to TxCON is recommended after writing to the TMRxH/L registers and cannot find it. It might be for an older processor, or maybe I read it on a forum somewhere and now it's that propagating myth. Sorry.

[louislouis]

anyways here is my take on the 7 seg display
if you have a chip with mssp why waste time and code space when the hardware can do it for you

I cheated a bit and did it in asm for speed and size gains
no nasty pauses , all gone
my displays are common anode so the data is inverted see comments

Hello Richard, thanks for response. Your code is probably for 4 digit 7 segment display where the segments is driven via 74HC595 shift register, and the common anodes via transistors directly from MCU or for multiplexing a bare display whitout driver right?

Look at mi first post, my display is driven by two 74HC595 shift register, one for segments, and the second for digits (like common anodes/cathodes).

To send data I used:

 
SHIFTOUT DPIN, CPIN, MSBFIRST,[ones,%0001]  ;(segment pattern, digit position)

Now I tring to find more elegant way to extract ones, tens, hundreds and thousands like my previous solution:

 
setdisp:
segment = value//10
gosub look
ones=segment            ; extract ones

segment =  value/10 
segment = segment//10
gosub look
tens=segment            ; extract tens

segment =   value/100
segment = segment//10
gosub look
hundreds=segment        ; extract hundreds

segment = value/1000
gosub look
thousands=segment       ; extract thousands

Can you help me with it?