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Bread Heads - AVR Breadboard Programmers

I recently found myself needing to reuse some older prototypes for a newer project, as part of the repurposing I needed to flash an Arduino compatible bootloader on the AVR processors in them. The design didn't include an ICSP header so I wanted to find an easier way to flash them without having to desolder them. Enter the Bread Head, a design I saw on the Blondihacks site by Quinn Dunki. The Bread Head is a simple yet effective way to reprogram AVR chips in circuit - basically it provides a breakout for the ICSP header on a device you simply push over the AVR chip in circuit to reprogram it.…

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CNC Auxiliary Input Board

After a little mishap involving my CNC machine I have been slowly restoring it to working order with a few pitfalls on the way. This post describes a small Arduino compatible auxiliary input board I designed around a ATmega8 microcontroller. Overview I recently replaced the main control board on my CNC machine with a generic 3 axis controller (referred to as a 'chinese blue board' in most LinuxCNC references). It seems that when the old control board burnt out the inputs on the parallel port were damaged, I have ordered a replacement PCI card but it did lead me to consider alternative methods…

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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 could get out of the 8 pin DIP version of LPC810 microcontroller from NXP. This is one of the few ARM based controllers available in DIP format (the only other one I know of is also from NXP - the LPC1114. Some time ago I bought a Adafruit LPC810 Starter Kit and then later a handful of discrete LPC810 chips to fill u…

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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 post unfortunately so I thought a brief executive summary would be useful. My goal in this post is to describe how you can develop and test software targeted at my 6502 emulator - to achieve that I will describe how to; Compile a version of the TGL-6502 firmware that runs on a desktop computer (Linux or Win…

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Introducing the TGL-6502 Single Board Computer

Here is a project I've been working on over the past few weeks - a 6502 compatible single board computer with 128K of RAM, 128K of ROM and an IO expansion port. The reason I call it 'compatible' is because the role of the 6502 processor is being played by an emulator running on a 8 pin LPC810 ARM Cortex-M0+ processor. The emulated processor supports all the official 6502 instructions (the undocumented instructions are treated as NOPs) and it is not a cycle accurate emulation. The entire emulator fits in the 4K flash on the LPC810. The project is not yet complete, at this stage it is capable of…

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