Drive an MCP49XX series DAC with an AVR ATmega

Davide Gironi writes:

Driving that IC is pretty simple, expecially if you have a dedicated SPI hardware interface, like many microchip has.
The ATmega8, used in this example has a dedicated SPI Control Register (SPSR) that one can use to setup the SPI interface.
This library can drive more then one MCP49XX of the same series at the same time, this is done just by selecting the chip using a SS channel for each one.

See the full post on his blog.

Check out the video after the break.

Internet connected fire/smoke alarm project

Martin Harizanov blogged about his cheap DIY IoT smoke detector:

This project is an upgrade to a previous project of mine – the DIY IoT smoke alarm. It is a more advanced version that uses dedicated hardware rather than the generic “Funky” project + external components. In essence, the module integrates into cheap smoke detectors and provides wireless event transmission plus periodic battery measurements to cloud infrastructure using BBoilRF as a gateway (over MQTT).

More details on Martin’s corner on the web blog. See part 1 here.

Check out the video after the break.

A look inside a Marconi signal generator

A closer look at a Marconi Instruments signal generator @ jaeblog:

Recently I got a Marconi Instruments 2019 signal generator, capable of generating signals from 80Khz up to 1040Mhz. It can also modulate these signals with AM, FM and more. This instrument is from the mid 80s and is, as far as I can test, still in good operational order.
A signal generator capable of generating over 1Ghz is pretty impressive, especially in the 80s, so let’s have a look inside this unit and see how it’s made.

DIY Analog resource monitor for your PC

Sasa Karanovic posted detailed instructions of how to build a physical dashboard for your PC, that is available on GitHub:

The overall architecture is very simple; There is a python script that is running on a PC and collects CPU, memory, network and GPU usage. Then, it sends that information over serial COM port to the hardware monitor board for processing. New voltage values are calculated and passed to the digital-to-analog converter (DAC) which drives analog dials (galvanometers) by applying a voltage that will move the needle to a desired location. Super simple but it get’s the job done.

See the full post at sasakaranovic.com.

Check out the video after the break.

The Annoying CAPS LOCK warning buzzer

Glen Akins made a USB notification device that make annoying warning noise when CAPS LOCK is enabled:

The only way to make CAPS LOCK even more annoying was to make it audible! Now never type a password in all upper case, join 500 lines together in vi, or turn a harmless forum post into an ANGRY SCREED without warning again! This project uses a PIC16F1459 to monitor the USB output report containing the CAPS LOCK status from the connected PC. When CAPS LOCK is enabled, the PIC turns on an annoying warning buzzer.

Project details at bikerglen.com, see Part 1 here. All design files are available on github.

ATTiny85 Pulse oximeter with photoplethysmogram (PPG) display

tinyPulsePPG, an ATTiny85 Pulse Oximeter with Photoplethysmogram (PPG) display by Jeff Magee:

This project implemented on an ATTiny85 displays a moving Photoplethysmogram together with pulse rate and estimates of SpO2 – blood oxygen percentage. It uses an SSD1306 128×32 OLED display and a Max30102 sensor. It is emphasised that this should not be used for medical purposes. The computation of SpO2 is very approximate and not calibrated in any way. The project is an exercise in software and hardware parsimony.

Project info on GitHub.