Logic probes are used to test the logical states of a digital circuit. LEDs are used to indicate things like a high or low logic state, which helps makers troubleshoot issues. This simple version of a programmable logic probe takes out any complicated switches or settings and boils the concept down to a useful and easy device.
Once power is supplied, the probe can display logic high with a green LED, logic low with a red LED, and Hi-Z with a yellow indicator. Separately, a white LED indicates an edge transition, and a combination of yellow and white LEDs show high-frequency signals.
The probe includes the bootloader that works through the probe tip and is built around Atmel ATtiny45. You can update the firmware with a USB to UART adapter, so there’s no need to disassemble it to perform updates. Python scripts for generating update files are included as well.
When you power it on, the probe displays white on both LEDs for two reasons: to self-test and verify that all LEDs are functioning, and to show the bootloader is listening for a commands.
You can power the probe from 3.3 V or a 5 V supply. Reverse voltage project is included as well.
