SPI with a Blindfold On- speed up by letting go and trusting the machine

Constantly checking to see if the coast is clear feels responsible, but it wastes cycles. Sometimes it is better to leap (or load) without looking. With a little hand-coded assembly, we can run our AVR processor lock-step with the SPI hardware and blindly dump new bytes into it at precisely the right moment. Because we don’t spend any time reading and testing status bits, we can increase the maximum throughput by more than 20%. If the prospect of screamingly fast yet perfectly safe SPI turns you on, read on…
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Ghost Guitar – Self Strumming Strings

Normally fingers provide the force needed to set a guitar’s strings vibrating, but with some simple electronics we can make a self-strumming guitar that plays itself without any moving parts at all. It is better than magic- its physics! Click on for a full explanation of how it works and a video of the ghost guitar rocking itself out (it really does make some creepy and spooky sounds)…

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Plates vs Coils – An alternative approach to wireless power transmission

Inductive power transfer is all the rage. There are now easy chips that do all the hard work for you. It even came built-in on my new phone!

But what about capacitive power transmission?

How come I’ve never seen a product that uses plates rather than coils? Is capacitive power transfer possible? Practical? Let’s break out a roll of tinfoil and find out!

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AVR Timer-based One Shot Explained

Last time, we made one-shot pulses using the AVR’s built in hardware timer module. Today we are going to dive deep into the datasheets to see how this technique is able to coax the normally free-running timer into generating a single pulse. Along the way, we will learn about the low level rules that govern the operation of the timer, and use a trick or two to get around those rules. Read on!…

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The Perfect Pulse- generating precise one-shots on AVR8

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It is possible to generate one-shot pulses on an AVR that…

  1. Are as narrow as a single clock cycle (63 nanoseconds!)
  2. Are precise to a single clock cycle
  3. Will run to correct completion no matter what else the processor is doing 1
  4. Do not require you to turn off interrupts at all (!)
  5. Do not require any assembly code

These pulses are generated in pure hardware. They require a couple of instructions of interruptible code to fire. Once fired, they are completely autonomous and depend only on the system clock to run to completion.

Sound cool? Read on!

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Easy hack to allow an AVR Dragon to power the target device over the ISP cable

TL;DR: You can power a target device from an AVR Dragon over an ISP header by adding a jumper wire from the VCC pin to pin #2 on the header that you are *not* using.

I’ve been a big fan of the SparkFun Pocket AVR programmer, partly because it has a handy little switch that lets you send power to the target device…

Pocket AVR Switch

Unfortunately, I started getting “Error: Could not find USBtiny device” while programming boards using a jig…

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Battery Fuel Gauge with Zero Parts and Zero Pins on AVR

Blink LED Cropped

It can be nice to know how much battery power you have. It becomes critically important with LiPo batteries since you can permanently damage them by running the voltage down too low. Typically battery voltage detection requires adding a circuit with extra parts and their associated power requirements. Wouldn’t it be great to be able to do this using nothing but software? Read on for a no parts, no pins, no power solution…

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