(GIF for attention) This post describes a simple method of reading resistive and capacitive sensors using a standard PC sound card. Virtually any desktop or laptop could be turned into a simple data acquisition system using this method. Thanks to moderate system requirements, even the very old computers can be repurposed for this application. Socket 478 based platforms from early 2000’s with integrated sound cards are readily available for ~free from recycling bins and are perfectly capable of running the data acquisition software (thankfully, Debian still supports 32-bit platforms).

Quick, cheap and easy (cheap as in “free”, “free” as in “freedom”) alternative to both heavy backup solutions and lightweight git-repo based backups with much less overhead and better compression: 7-zip. 7-zip’s -u switch provides fine-grained control over creating and updating archives based on states of already-archived and to-be-archived files. The switch is specified as a combination of state-action flags (more info): State State condition File on Disk File in Archive p File exists in archive, but is not matched with wildcard ?

LUKS encryption, while convenient, can become a major pain when the drive gets corrupted. Many things can lead to it: accidental wipe/format of the boot partition accidental dd to a wrong drive (sure, you pressed ^C right away but your grub is gone, sorry) exceedingly “smart” utilities overwriting MBR or re-initializing encrypted partitions drive/memory failures (power outage, random bit flip, etc.) There are plenty of manuals on how to restore an accidentally wiped boot partition.

Consider this simple code snippet… 10 VALVE1_POS = S405_VH(1400) 20 VALVE2_POS = 80.0 30 IF VALVE1_POS > 50.0 THEN VALVE3_POS = 99.5 ELSE VALVE3_POS = 0.5 …and let me follow your observations: you notice a weird line enumeration, just like in good old BASIC, you see three variables, VALVE1_POS, VALVE2_POS and VALVE3_POS, you find S405_VH(1400) most likely to be a function call retrieving a position of the valve 1, position of the valve 2 is set to 80.

Docker is known to not to support 32-bit hosts. As per debian installation instructions: Docker CE is supported on x86_64 (or amd64), armhf, and arm64 architectures. 32-bit hosts are unlikely to become supported either – “let’s bring docker on 32-bit” issue was closed and locked back in 2014. Nothing fundamentally prevents docker (including latest version of docker CE) from running on 32-bit platforms. I am currently running a slightly outdated version 18.

I ran into a rather funny bug recently – when recording audio on an RPi with Raspbian Jessie via an external USB sound card, arecord doesn’t stop recording after a period of time specified by --duration flag, but keeps running and filling files *-01.wav, *-02.wav, etc. with garbage data. Googling doesn’t return a solution, except an obvious one to killall -KILL arecord. USB microphones are also affected. Since I have another RPi running Wheezy and showing no symptoms of the bug (and being free of systemd malware ;), the bug is likely in arecord itself.

Maxim 31855 chips are cheap and simple to use K-type thermocouple amplifiers. They’re equipped with a digital SPI interface with libraries available for both Raspberry Pi and Arduino boards. MAX31855 breakout boards are available from Adafruit. The datasheet specifies the accuracy of ±2°C within the temperature range from -200°C to +700°C. However, close to the lower bound of this range, the accuracy of reported temperature is affected by linearized volt-to-degree conversion.

Fire TV is an awesome htpc replacement. It still requires rooting and, if you want to watch US Netflix shows outside of US, installing a VPN client. Rooting is straightforward – I just followed this guide. Installing OpenVPN is a bit more tricky. Even though there are few tutorials (e.g. this one or this one), recommended installer apk doesn’t work on my Fire TV. This tutorial recommends unpacking the OpenVPN binary manually to /system/xbin/.