CD4094BE Arduino problems

Question

I'm trying to build a circuit which uses three 4094's to give me enough outputs to drive a number of LED's. I've built a few similar circuits before in the past using the same code and schematic, but for some reason this time I'm having problems controlling the shift registers.

The first 4094 is connected to my Arduino UNO using the following outputs:

CD4094_CLOCK  - Digital 2
CD4094_DATA   - Digital 3
CD4094_STROBE - Digital 4

For the sake of testing I've connected the 4094 OEs to +5V, but they will be on a PWM pin in reality. I've connected all the 4094 STROBE and CLOCK inputs as I've done previously, too.

I'm using the following program, however no matter what value I shiftOut to the 4094's most of the outputs stay high:

// CD4094 Constants
#define CD4094_CLOCK    2
#define CD4094_DATA     3
#define CD4094_STROBE   4
//#define CD4094_OE     3

char Display1 = 0, Display2 = 0, Display3 = 0;

void setup() {
    pinMode(CD4094_CLOCK, OUTPUT);
    pinMode(CD4094_STROBE, OUTPUT);
    pinMode(CD4094_DATA, OUTPUT);
    //pinMode(CD4094_OE, OUTPUT);
}

void loop() {
    Display1 = 63;
    Display2 = 6;
    Display3 = 91;

    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display3);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display2);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display1);

    digitalWrite(CD4094_STROBE, HIGH);
    digitalWrite(CD4094_STROBE, LOW);

    delay(3000);

    Display1 = 0;
    Display2 = 0;
    Display3 = 0;

    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display3);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display2);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display1);

    digitalWrite(CD4094_STROBE, HIGH);
    digitalWrite(CD4094_STROBE, LOW);

    delay(3000);
}

Here's a picture of my breadboard too, in case it could help someone?

Does anyone have any suggestions on how I can debug this sort of issue? The only tools I have are my multimeter and Arduino boards. Is there some kind of problem with my code?

Answer 1

The strobe signal is configured as output but never initialized as high. The code you provided just flicks it high for a moment then holds it low during transmission. If I understand the datasheet correctly, the strobe must be held high during your data transmission

Answer 2

// CD4094 Constants
#define CD4094_CLOCK    18
#define CD4094_DATA     19
#define CD4094_STROBE   17
#define CD4094_OE     16

char Display1 = 1, Display2 = 2, Display3 = 3;

void setup() {
    pinMode(CD4094_CLOCK, OUTPUT);
    pinMode(CD4094_STROBE, OUTPUT);
    pinMode(CD4094_DATA, OUTPUT);
    //pinMode(CD4094_OE, OUTPUT);
}

void loop() {
    Display1 = 63, 6, 91, 79, 102, 109, 125, 7, 127, 111;
    Display2 = 63, 6, 91, 79, 102, 109, 125, 7, 127, 111;
    Display3 = 63, 6, 91, 79, 102, 109, 125, 7, 127, 111;

    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display3);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display2);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display1);

    digitalWrite(CD4094_STROBE, HIGH);
    digitalWrite(CD4094_STROBE, LOW);

    delay(3000);
    Display1 = 0;
    Display2 = 0;
    Display3 = 0;

    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display3);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display2);
    shiftOut(CD4094_DATA, CD4094_CLOCK, MSBFIRST, Display1);

   digitalWrite(CD4094_STROBE, HIGH);
   digitalWrite(CD4094_STROBE, LOW);
   delay(30);
}