Digital IC Checker

Digital ICs, such as NAND, NOR, AND, OR, XOR, Decoder, and Encoder ICs, are essential building blocks for creating digital circuits. I keep a collection of these ICs in both DIP through-hole and SMD packages. After repeated use in various breadboard circuits, some ICs occasionally develop faults, such as one or two non-functional gates or complete failure of the IC. Identifying faulty ICs can be challenging, especially when they are part of a larger circuit. Therefore, I prefer to test these ICs before using them in a new project. However, manually testing all the combinations for every gate is a time-consuming process.

To address this issue, I devised a simple yet unique solution to automatically test these ICs using a Raspberry Pi Pico. The Raspberry Pi Pico’s GPIO pins are connected to each pin of the digital IC being tested. The Pico is then programmed to configure its GPIO pins as inputs or outputs based on the IC’s pin configuration. Finally, digital input signals are sent, and the corresponding digital outputs are measured. If all the outputs matches the predefined values, the digital IC is functioning correctly; otherwise, the IC has an issue.

Hardware setup:

I designed a PCB featuring a Raspberry Pi Pico and several IC sockets to accommodate ICs with various pin counts, along with some passive components and voltage regulators. Additionally, a two-color LED is included to indicate the final output status of the test. Here is the circuit file: https://oshwlab.com/arghyabiswas05/digital-ic-checker

Source code:

On the software side, I use the default Raspberry Pi Pico MicroPython bootloader along with our custom, simple Python-based framework specifically designed for this project. The Python source code is available at https://github.com/inovaloy/digital_IC_checker

The framework contains two main components: the actual Python firmware source code and a firmware upload script named upload_firmware.py. In the firmware source code, main.py serves as the entry point, while dicc_pin.py contains the pin definitions for the PCB. For each digital IC, there is a dedicated folder named in the format IC<IC number>. For example, for the 2-input 4-NAND gate IC 7400, the folder is named IC7400.

Each folder must contain two Python files named ic<IC number>.py and ic<IC number>_pin.py. For example, the IC7400 folder contains ic7400.py and ic7400_pin.py. The ic7400_pin.py file defines the pin mapping between the PCB pins and the IC pins. The other file, ic7400.py, contains the actual testing logic. This file must include a main() function, which is required to return an exit code.