Intro: Understanding 74LS273 Octal D Flip-Flop IC
I got my hands on 74LS273 IC while I was salvaging some components from an old satellite receiver, something I do between projects and save some money….
This IC was on the control panel and was wired to 4-Digits 7-Segments LED display with some transistors. This made me interested to see how it works. I never used one before and therefore I had no idea how to wire it in order to make good use of it.
I made few internet searches but couldn’t find any wiring diagram or sample circuit that would help me out. There are many datasheets and pinout readily available…. that was useful and a good start for me.
Step 1: Part List:
In order to have a good understanding of how the 74LS273 functions, I had decided to build a simple circuit with visual presentation for the output; a sequence of numbers is always a good idea therefore I decided on 1-Digit 7-Segmnet LED Display, and instead of running it manually, I decided to automate the process somewhat by using a microcontroller (Arduino). The following are the components needed:
- 74LS273 Octal D Flip-Flop IC
- Arduino NANO
- 1-Digit 7-Segment LED Common Cathode Display
- 8x 200 Ohm Resistors (value depends on the 7-Seg. LED Display)
- Hook-up Wires
- 5 VDC Power Source
Step 2: 74LS273 Pinout:
Before building the circuit, let us have some understanding of the process which I am about to have the Arduino to follow:
- The 74LS273 IC has 8 data input pins and 8 latching Flip-Flop output pins, also it has 2 inputs pins for Clear and Clock.
- In order to display a digit you could follow these steps:
o Set all data pins to LOW
o Set Clear pin to LOW then set it to HIGH
o Set required data pins to HIGH; these pins correspond to the digit you need to display
o Set Clock pin to LOW then set it to HIGH
Step 3: Here Is the Hardware Hock-up Diagram:
I ran into some difficulty therefore I tried 10K pull-down resistor on Arduino pin-11 and 10K pull-up resistor on Arduino pin-10, this solved the problem. But I had removed them afterward once I got the circuit working well. The resistors helped me during testing, but they are not necessary afterward.
Step 4: Arduino Code:
Step 5: Video:
Enjoy.... Hope this was useful.....