In my previous post I showed how to restart Bluetooth on Debian Linux. Here I explain how to disable Bluetooth auto-suspend with a kernel module option. The behaviour of kernel modules can be controlled with parameters. The command modinfo shows information about a module and lists its parameters. In the example below, modinfo btusb shows …
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On my laptop I use a Bluetooth keyboard and a Bluetooth mouse. Occasionally the Bluetooth adapter in the laptop shuts off completely, meaning that it becomes impossible to restart the Bluetooth service with sudo systemctl restart bluetooth.service. My troubleshooting points to powersaving as the cause of this intermittent failure, but the TLP setting that is …
WiFi connections from my laptop became unstable after I upgraded it to Ubuntu 19.04. To get them to work, I had to turn the WiFi adapter on and off several times, which quickly became annoying. The following attempts to fix the problem were unsuccessful: disabling IPv6 disabling power-saving on the WiFi adapter setting bt_coex_active=0 during …
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Stack Overflow question ‘Inputting list of passwords in a class’ is more interesting as an object-oriented design (OOD) exercise than as a debugging exercise, but it also provides an opportunity to practise some Python programming. The requirements identified in the problem are: represent a set of credentials comprised of a username and a password; represent …
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Undefined behaviours in the C language confuse many beginners. As an occasional C programmer I am also baffled when I encounter them—as happened with this code that I wrote in an Arduino sketch. static void get_input(String prompt, void* const input, void (*parse_func)(void* const), int (*validate_func)(const void* const)) { while (!validate_func((const void* const)input)) { Serial.println(prompt); while …
As a fun way to improve my C, I started programming the Arduino using Atmel Studio instead of the friendlier Arduino IDE. Below is my very first program. It blinks a red LED and a white LED according to a preset pattern. #define F_CPU 16000000UL #include <avr/io.h> #include <util/delay.h> struct Led { int pin; int …
We use smtpop.dll in one application to retrieve email from a POP3 mailbox. Today we had to connect to a mailbox over SSL, which smtpop.dll does not support. Our code to retrieve email is abstracted behind a façade class, so I expected to simply substitute a new library for smtpop.dll and to call new methods. …
From http://thoughtworks.fileburst.com/assets/technology-radar-jan-2014-en.pdf: We continue to see teams run into trouble using JSF– JavaServer Faces — and are recommending you avoid this technology. Teams seem to choose JSF because it is a J2EE standard without really evaluating whether the programming model suits them. We think JSF is flawed because it tries to abstract away HTML, CSS …
This morning a deployment failed catastrophically. One of the scripts for upgrading the database caused several objects to be dropped unexpectedly. We restored the database from backup, corrected the script, and repeated the deployment, which was successful. We now had to do a retrospective to learn what went wrong and how to avoid it in …
Robert Binder’s Testing Object-Oriented Systems book sits permanenly on my desk. At over 1500 pages long, it is almost a never-ending read, but from time to time I pause to read a few choice chapters. Binder also wrote about the compliance testing of Microsoft’s court-ordered publication of its Windows client-server protocols in 2012. An interesting …