Hello everyone, this is my first Arduino project attempt after completing the Arduino Starter Kits Project book, so please bear with me.
I have an Arduino Uno R3, with a breadboard and three 74HC595s. The goal is to make a LED clock with 17 LEDs. The maximum LED count with two 74HC595s is 16, so, I need another one for the 17th. I know from the forums that there are other ways to do this, and I know that it's recommended to have 0.1µF decoupling capacitors. I don't have those, I should order them I guess.
Anyway, I had everything working fine with two 74HC595s, was able to animate the LEDs. But then I added the third 74HC595 and... for some reason it's doing the same as the first one. Here's a picture. of my setup with no LEDs attached.
I have followed this schematic, it seems pretty intuitive (and I used 3, not 4 chips):
When I blink a single LED, pin 15 on the third (top on my picture) 74HC595, acts the same as pin 15 on the first (bottom) 74HC595.
I have tested it using the following code:
#include <ShiftRegister74HC595.h>
const int numberOfShiftRegisters = 3; // number of shift registers attached in series
const int serialDataPin = 2; // DS
const int clockPin = 3; // SHCP
const int latchPin = 4; // STCP
ShiftRegister74HC595<numberOfShiftRegisters> sr(serialDataPin, clockPin, latchPin);
void setup() {
sr.setAllLow();
}
void loop() {
sr.set(0, HIGH);
delay(100);
sr.set(0, LOW);
delay(100);
}
What am I doing wrong? Note: using sr.set(16, HIGH) does nothing to pin 15 on chip 3.
.
but good that you say this, because these uncommon units (micro, nano, pico) are so uncommon. It looks like the Arduino Starter Kit has 5x100nF, and 5x100pF. For three HC595s I need 6x100nF but ok, at least I can experiment a bit with these 5. I'll make a picture.
