[PIC] Using 74165 and 74595 with PIC 16F877

[eldvin1]

Hi all,


I'm trying to extend both input and output pin numbers of PIC 16F877. I'm using 2 x 74HC595 and 2 x 74HC165. It's nearly working but when I hit the first pin of first 74HC165 It's not working. When I hit the second one, both first and second pin of 74hc595 working.

The other problem is when I hit the last pin of second 74hc165 first 74hc595 is not working anymore.

What will be the problem? Here I have added schematic and zip file of both code and schematic. Thanks in advance.

PS: Working with CCS C

 

[eldvin1]

I really need a help. Here is the problem I have:





Here are the codes;

74595.c

#IFNDEF EXP_OUT_ENABLE

#define EXP_OUT_ENABLE  PIN_B4
#define EXP_OUT_CLOCK   PIN_B5
#define EXP_OUT_DO      PIN_B6
#define NUMBER_OF_74595 2

#ENDIF


void write_expanded_outputs(byte* eo) {
  byte i;

  output_low(EXP_OUT_CLOCK);
  output_low(EXP_OUT_ENABLE);

  for(i=1;i<=NUMBER_OF_74595*8;++i) {  // Clock out bits from the eo array
    if((*(eo+(NUMBER_OF_74595-1))&0x80)==0)
      output_low(EXP_OUT_DO);
    else
      output_high(EXP_OUT_DO);
   shift_left(eo,NUMBER_OF_74595,0);
   output_high(EXP_OUT_CLOCK);
   output_low(EXP_OUT_CLOCK);
  }
  output_high(EXP_OUT_ENABLE);
}

74165.c

#IFNDEF EXP_IN_ENABLE

#define EXP_IN_ENABLE   PIN_B4
#define EXP_IN_CLOCK    PIN_B5
#define EXP_IN_DI       PIN_B6
#define NUMBER_OF_74165 2

#ENDIF


void read_expanded_inputs(byte *ei) {
  byte i;

  output_high(EXP_IN_CLOCK);
  output_low(EXP_IN_ENABLE);      // Latch all inputs
  output_high(EXP_IN_ENABLE);

  for(i=1;i<=NUMBER_OF_74165*8;++i) {      // Clock in bits to the ei structure
    shift_left(ei,NUMBER_OF_74165,input(EXP_IN_DI));
    output_low(EXP_IN_CLOCK);
    output_high(EXP_IN_CLOCK);
  }
  output_low(EXP_IN_ENABLE);
}

Here is my main function

#include "16F877.h"
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600,xmit=pin_c6,rcv=pin_c7,parity=N,stop=1)

#include <C:\Users\BASGAN\Desktop\Embedded Control Final\Soru_2\kod\74595.c>
#include <C:\Users\BASGAN\Desktop\Embedded Control Final\Soru_2\kod\74165.c>
#include <math.h>

int adana;
main() {
   byte data;

   do {
   adana++;
   
   if (adana%2==0)
      {   
            read_expanded_inputs (&data);
      }
      else
      {
            output_low(PIN_B3);
            write_expanded_outputs (&data);
      }
   } while (TRUE);
}

 

[zuisti]

Hi;
First of all:
- both IC you are using (HC595 and HC164) are serial-to-parallel converters but only for outputs. For parallel-to-serial converting (ie for inputs) have to use for example a CD4021 like in my old project. See the picture and the attached Proteus simulation. Its program was written in mikroC (not in CCS C) so does not attached here.

- second (and this is important):
All above ICs are positive edge controlled (for example the 595 stores the values at the raising edge of its ST_CL input or shifts in the new data at the raising edge of its SH_CL).
Have to revise your code ...