GreenPak Programmable Matrix

I had a batch of PCBs arrive yesterday which included the boards for my ESP8266 based sensor system so I should be able to do a followup post on that project in the near future. This batch also included my breakout boards for GreenPak 3 mixed signal programmable logic chips.…

Ohms Law and Resistor Networks

This post describes how I use Python code to apply Ohms Law to a resistor network to help select optimum component values that don't exceed the operating limits of an IC. In order to determine if the idea I had for controlling a LM317 regulator with a digital potentiometer was…

Design Idea: Software Controlled Regulator

This post describes the design of a software controlled voltage regulator. At this point I am still trying to determine if the design is feasible within the limits of the components I have available. I have been toying around with ideas for small software controlled modules I can use for…

UART Based Networking for Microcontrollers

This article describes a simple networking system that supports multiple slave devices connected to a single serial port on the host system. The microcontroller side only requires a UART and can be implemented with a minimal amount of code. Background Almost two years ago I designed and built a small…

TGL-6502 Hardware Design

In this post I describe the hardware design of the TGL-6502 emulator board. The full schematic is available in the GitHub repository (PDF), it might be worth opening it in another window for reference while reading this post. I started this project as a challenge to see how much I…

Programming the TGL-6502

This post describes how to develop software for my TGL-6502 emulator board. The most recent update to the GitHub repository includes a desktop implementation of the emulator software so you don't need to build the hardware to write and test programs. Overview This is going to be a very long…

A Simple Serial (I2C/SPI) EEPROM Programmer

This is a small ATtiny84 based device to program I2C and SPI EEPROM chips over a serial port. As usual all code and schematics are available in GitHub. Background The TGL-6502 project uses an SPI EEPROM (the Microchip 25AA1024) to simulate the ROM exposed to the 6502 processor. To get…

On the Importance of Patience

Using some patience and taking some extra time to double check things can save a lot of problems in the long run. This is one of those things that we all know we should be doing but often fail to do in practice. Here is a concrete example where failing…