Noting that the Intel 4004 was normally sold as a chip set called the Intel MCS-4, the standard clock circuit used appears to be this (from this PDF, kindly provided by this vendor of MCS-4 test boards): Which means I want to work out what this circuit is doing. First off, let’s understand these flip…
Tag: electronics
Adventures in exploding power supplies
So this went well… The Intel 4004 microprocessor has slightly weird power supply requirements by modern standards. You see, it needs to be supplied with +5V DC, and -10V DC at the same time to work. (It turns out that this is an artifact of the MCS-4 chipset using PMOS technology not the more modern…
Raspberry Pi HAT identity EEPROMs, a simple guide
I’ve been working on a RFID scanner than can best be described as an overly large Raspberry Pi HAT recently. One of the things I am grappling with as I get closer to production boards is that I need to be able to identify what version of the HAT is currently installed — the software…
1-Wire home automation tutorial from linux.conf.au 2019, part 3
This is the third in a set of posts about the home automation tutorial from linux.conf.au 2019. You should probably read part 1 and part 2 before this post. In the end Alistair decided that my home automation shield was defective, which is the cause of the errors from the past post. So I am…
Gangscan 0.6 boards
So I’ve been pottering away for a while working on getting the next version of the gang scan boards working. These ones are much nicer: thicker tracks for signals, better labelling, support for a lipo battery charge circuit, a prototype audio circuit, and some LEDs to indicate status. I had them fabbed at the same…
Using a MCP4921 or MCP4922 as a SPI DAC for Audio on Raspberry Pi
I’ve been playing recently with using a MCP4921 as an audio DAC on a Raspberry Pi Zero W, although a MCP4922 would be equivalent (the ’22 is a two channel DAC, the ’21 is a single channel DAC). This post is my notes on where I got to before I decided that thing wasn’t going…
1-Wire home automation tutorial from linux.conf.au 2019, part 2
For the actual on-the-day work, delegates were handed a link to these instructions in github. If you’re playing along at home, you should probably read 1-Wire home automation tutorial from linux.conf.au 2019, part 1 before attempting the work described here. Its especially important that you know the IP address of your board for example. Relay tweaks…
1-Wire home automation tutorial from linux.conf.au 2019, part 1
I didn’t get much of a chance to work through the home automation tutorial at linux.conf.au 2019 because I ended up helping others in the room get their Orange Pi is booting. Now that things have settled down after the conference, I’ve had a chance to actually do some of the tutorial myself. These are…
Introducing GangScan
As some of you might know, I am a Scout Leader. One of the things I do for Scouts is I assist in a minor role with the running of Canberra Gang Show, a theatre production for young people. One of the things Gang Show cares about is that they need to be able to…
Support for Raspberry Pi and Orange Pi GPIOs in Home Assistant
So, I’ve been off in the GPIO library salt mines for a while, but am now ready to circle back and document how to get GPIO inputs and outputs working in Home Assistant. This now works on both Raspberry Pi and OrangePi, assuming that my patch gets merged. First off, let’s talk about GPIO outputs….