SN74LV8154: counter resets of RCLK is connected

Apurv Mishra

Part Number: SN74LV8154

Hey, everyone!

I am using SN74LV8154 binary counter with Hercules RM57Lx LaunchPad. It counts but keeps resetting at 15 or 7 (or sometimes less).

After investigating, I observed that when I remove the RCLK connection for a while and then connect it back, the counts' value it shows is more than 15 (e.g. 20-30, 100, 8852, etc.). I checked multiple times. When RCLK is not connected, it counts fine but resets when RCLK is connected.

Please, help!

Thanks,
Apurv

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 280020 points

Schematic?

0 Apurv Mishra over 5 years ago in reply to Clemens Ladisch

Intellectual 750 points

I do not have a clean drawn schematic but the connections are the following:

(left side is SN74LV8154)

Y0-Y7 ----- GIOA 0, 1, 2, 5, 6, 7, GIOB 2, 3
VCC ----- 5V
GND ----- GND
GAL ----- HET1_2
GAU ----- HET1_18
GBL ----- HET1_16
GBU ----- HET1_30
CLKA ----- HET1_22
CLKB ----- (not connected)
RCLK ----- HET1_14
CCLR ----- HET1_4
(RCOA and CLKBEN shorted)

Please, find the code attached as well.

HL_sys_main.c

/* pin configurations:
 *
 * GIOA 0,1,2,5,6,7, GIOB 2,3 : to read the 8-bit parallel data
 *
 * GAL : HET1[2]
 * GAU : HET1[18]
 * GBL : HET1[16]
 * GBU : HET1[30]
 *
 * RCLK : HET1[14]
 * CCLR : HET1[4]
 *
 * CLK : HET1[22]
 */

// include files
#include "HL_sys_common.h"
#include "HL_gio.h"
#include "HL_sci.h"
#include "HL_het.h"
#include <stdio.h>

#define GAL 2
#define GAU 18
#define GBL 16
#define GBU 30
#define RCLK 14
#define CCLR 4
#define CLK 22

char count[20];

void main()
 {
    uint32 freq = 0;
    uint8 b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16,b17,b18,b19,b20,b21,b22,b23,b24,b25,b26,b27,b28,b29,b30,b31;

    __delay_cycles(10);

    // Initialize GIO driver
    gioInit();

    // Initialize SCI driver
    sciInit();

    // Initialize HET driver
    hetInit();

    // setting HET1 driver pins as output
    gioSetDirection(hetPORT1, 0xFFFFFFFF);

    //setting GIOA and GIOB driver pins as input
    gioSetDirection(gioPORTA, 0x00000000);
    gioSetDirection(gioPORTB, 0x00000000);

    // initialization of the register
    gioSetBit(hetPORT1, GAL, 1);
    gioSetBit(hetPORT1, CCLR, 0);
    gioSetBit(hetPORT1, GAU, 1);
    gioSetBit(hetPORT1, GBL, 1);
    gioSetBit(hetPORT1, GBU, 1);
    gioSetBit(hetPORT1, RCLK, 0);
    gioSetBit(hetPORT1, CCLR, 1);
    gioSetBit(hetPORT1, CLK, 0);

    while (1)
    {
        freq = 0;

        // set CLOCK pulse
        gioSetBit(hetPORT1, CLK, 1);
        __delay_cycles(11);
        gioSetBit(hetPORT1, CLK, 0);

        // set RCLK pulse
        gioSetBit(hetPORT1, RCLK, 1);
        __delay_cycles(33);
        gioSetBit(hetPORT1, RCLK, 0);

        // read GBU byte
        gioSetBit(hetPORT1, GBU, 0);

        // read bits
        b31 = gioGetBit(gioPORTB, 3);
        freq = freq|b31;
        freq<<=1;
        b30 = gioGetBit(gioPORTB, 2);
        freq = freq|b30;
        freq<<=1;
        b29 = gioGetBit(gioPORTA, 7);
        freq = freq|b29;
        freq<<=1;
        b28 = gioGetBit(gioPORTA, 6);
        freq = freq|b28;
        freq<<=1;
        b27 = gioGetBit(gioPORTA, 5);
        freq = freq|b27;
        freq<<=1;
        b26 = gioGetBit(gioPORTA, 2);
        freq = freq|b26;
        freq<<=1;
        b25 = gioGetBit(gioPORTA, 1);
        freq = freq|b25;
        freq<<=1;
        b24 = gioGetBit(gioPORTA, 0);
        freq = freq|b24;
        freq<<=1;

        // set GBU to HIGH again
        gioSetBit(hetPORT1, GBU, 1);


        // read GBL byte
        gioSetBit(hetPORT1, GBL, 0);

        // read bits
        b23 = gioGetBit(gioPORTB, 3);
        freq = freq|b23;
        freq<<=1;
        b22 = gioGetBit(gioPORTB, 2);
        freq = freq|b22;
        freq<<=1;
        b21 = gioGetBit(gioPORTA, 7);
        freq = freq|b21;
        freq<<=1;
        b20 = gioGetBit(gioPORTA, 6);
        freq = freq|b20;
        freq<<=1;
        b19 = gioGetBit(gioPORTA, 5);
        freq = freq|b19;
        freq<<=1;
        b18 = gioGetBit(gioPORTA, 2);
        freq = freq|b18;
        freq<<=1;
        b17 = gioGetBit(gioPORTA, 1);
        freq = freq|b17;
        freq<<=1;
        b16 = gioGetBit(gioPORTA, 0);
        freq = freq|b16;
        freq<<=1;

        // set GBL to HIGH again
        gioSetBit(hetPORT1, GBL, 1);


        // read GAU byte
        gioSetBit(hetPORT1, GAU, 0);

        // read bits
        b15 = gioGetBit(gioPORTB, 3);
        freq = freq|b15;
        freq<<=1;
        b14 = gioGetBit(gioPORTB, 2);
        freq = freq|b14;
        freq<<=1;
        b13 = gioGetBit(gioPORTA, 7);
        freq = freq|b13;
        freq<<=1;
        b12 = gioGetBit(gioPORTA, 6);
        freq = freq|b12;
        freq<<=1;
        b11 = gioGetBit(gioPORTA, 5);
        freq = freq|b11;
        freq<<=1;
        b10 = gioGetBit(gioPORTA, 2);
        freq = freq|b10;
        freq<<=1;
        b9 = gioGetBit(gioPORTA, 1);
        freq = freq|b9;
        freq<<=1;
        b8 = gioGetBit(gioPORTA, 0);
        freq = freq|b8;
        freq<<=1;

        // set GAU to HIGH again
        gioSetBit(hetPORT1, GAU, 1);


        // read GAL byte
        gioSetBit(hetPORT1, GAL, 0);

        // read bits
        b7 = gioGetBit(gioPORTB, 3);
        freq = freq|b7;
        freq<<=1;
        b6 = gioGetBit(gioPORTB, 2);
        freq = freq|b6;
        freq<<=1;
        b5 = gioGetBit(gioPORTA, 7);
        freq = freq|b5;
        freq<<=1;
        b4 = gioGetBit(gioPORTA, 6);
        freq = freq|b4;
        freq<<=1;
        b3 = gioGetBit(gioPORTA, 5);
        freq = freq|b3;
        freq<<=1;
        b2 = gioGetBit(gioPORTA, 2);
        freq = freq|b2;
        freq<<=1;
        b1 = gioGetBit(gioPORTA, 1);
        freq = freq|b1;
        freq<<=1;
        b0 = gioGetBit(gioPORTA, 0);
        freq = freq|b0;

        // set GAL to HIGH again
        gioSetBit(hetPORT1, GAL, 1);

        printf("%d\r\n", freq);
        //sciSend(sciREG1, sizeof(count), count);
    }
}

Thanks!

0 Gabriel Lake1 over 5 years ago in reply to Apurv Mishra

TI__Expert 3450 points

Hi Apurv,

Your code appears fine. RCLK should not cause the counter to clear, do you have access to an oscilloscope to see if CCLR is glitching low for some reason when RCLK is connected? Also make sure your delay function is meeting the timing requirements for this device.

regards,

Gabriel

0 Apurv Mishra over 5 years ago in reply to Gabriel Lake1

Intellectual 750 points

Hi, Gabriel!

I connected CCLR to an oscilloscope. Whenever the oscilloscope connection was there, CCLR remained high and the count values kept showing as 0. But when the oscilloscope connection was removed, it counted like before (resetting at 15).

Also, when CCLR is high, the voltage value is around 1.25V. Shouldn't it be 3.3V ?

Thanks and regards,
Apurv

0 Clemens Ladisch over 5 years ago in reply to Apurv Mishra

Guru 280020 points

This sounds as if CCLR is floating, i.e., HET1_4 does not actually drive a valid voltage. Please check the connection.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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SN74LV8154: counter resets of RCLK is connected