MPU9250, continued

This is a note on building support for the MPU9250 9-axis chip in the AdaPilot project (the AdaRacer hardware). It continues this report.

Invensense MPU9250 via SPI

This is a note on building support for the MPU9250 9-axis chip in the AdaPilot project (the AdaRacer hardware; the prototype board I have is subtly different from the one shown).
9-axis means it can measure each of acceleration, gyro and magnetic field values in 3 axes, which is very useful if your drone needs to know about its own motion.

Audacity 2.1.2 and El Capitan

I wanted to update Audacity, but the 2.1.2 version (from the official download site) wouldn’t run: I got can’t open application Audacity.

The application is damaged and can't be opened

I downloaded a new version of eclipseArduino (Arduino development within Eclipse). After unpacking and moving to /Applications, I get the message

"eclipseArduino" is damaged and can't be opened. You should move it to the Trash.

Huh.

After a lot of poking around, I found this:

1. Open Gatekeeper settings located in System Preferences > Security & Privacy.
2. Set Allow applications downloaded from: to Anywhere and confirm by pressing Allow From Anywhere.
3. Run the application.
4. Once the application has been successfully launched, it no longer goes through Gatekeeper; so, restore Gatekeeper settings to the default option Mac App Store and identified developers after successfully launching the application.

IO Expansion

I started checking out AdaCore's support library for STM32F4 boards, particularly to use I2C to talk to the PCF8547A IO expander (for possible use on the AdaPilot project).

I seem to have fritzed one or two of the pins on my STM32F429I-DISC0 board (now replaced by an updated version, STM32F429I-DISC1; that last character was a 0!); after some hair-pulling it turns out that one of said pins is used by the only externally-accessible I2C peripheral on the board; so, until the replacement arrives, here are some interesting facts about the PCF8547A.

Recovering an STM32F4 board

This is a note on overcoming a problem connecting to my STM32F429I-DISCO board.

Programming the Arduino in Eclipse

This is a note on installing the Eclipse Arduino Plugin, specifically on Windows (32-bit), with pointers to archived materiel.

Arduino Due and the Watchdog

A watchdog is used to detect when a system has gone off with the fairies; you have to reset the watchdog timer ("pat the watchdog") every so often or it takes some recovery action. In the case of the Arduino Due, with the ATSAM3X8E MCU, the recovery action is to reset the CPU.

In the ATSAM3X8E (and probably other Atmel MCUs, too), the watchdog timeout defaults to 16 seconds, and the default hardware state is that the watchdog is enabled! (the default in the Atmel Software Framework is to disable the watchdog unless you have defined CONF_BOARD_KEEP_WATCHDOG_AT_INIT).