BeagleBone

BeagleBone Black
Owner	User:zmatt
Status
Hostname	bbb
Tool
Tool category

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Description

BeagleBone Black (rev C), donated by my employer Dutch & Dutch. It has one minor defect: one I/O pin (P9.26 / GPIO 0.14) has been damaged, probably by overvoltage, and has become unusable. I've stuffed it with polycaprolactone to clearly mark it and avoid accidental use.

Like most of our BBBs it also has a small patch: the separate regulator for "VDD_3V3B" has been removed and the voltage rail has been tied to the "VDD_3V3A" instead, which means it has a single unified 3.3V rail. This patch was done to avoid the problem where the 3V3B remains enabled too long during poweroff and indefinitely if the BBB is supplied via battery power. With this patch the BBB can be safely powered via its battery terminals (single Li-ion cell, BBB has integrated charger). An obvious side-effect is that less power can be drawn from the BBB's 3.3V supply by external hardware. See here for more info on BBB power supply infrastructure.

Information on pin functions can be found in this spreadsheet. Laminated printouts of the P9 and P8 tabs are somewhere in the space in cha0z97's drawer, along with some other documentation.

Hardware safety notes

The expansion header pins connect to the processor without any real protection, and being careless can destroy an IO or the entire processor.

The digital I/Os are 3.3V and are NOT 5V-tolerant.

The ADC inputs are max 1.8V. Due to a hardware erratum they may be briefly shorted together and/or to vdd or ground during power-up, hence it is recommended to avoid connecting them to low-impedance outputs (e.g. opamps) without a series resistor.

Avoid injecting current into IOs when the beaglebone is powered off. In particular, the digital I/Os are NOT 3.3V-tolerant when the 3.3V supply is off.

Playing with it

Battery pack has been attached, can be charged via USB or the 5V DC barrel jack (1A or more recommended, but less should work too). Use script mentioned below to check its status. Running on battery power will almost certainly render the USB host port inoperable.

URL of web interface, cloud9 IDE, and SSH login and password are currently on a piece of paper on the BBB. Quite a bit of javascript on the web interface is broken, but the cloud9 IDE seems to work... mostly.

I've installed/written a bunch of utility scripts:

• gpio-parse can convert between various ways of identifying GPIOs
• sudo gpio-export exports a GPIO via sysfs (accepts any format that gpio-parse, prints the sysfs paths)
• sudo gpio-unexport removes such exports
• sudo show-pins detailed overview of pin config and usage
• ~/charger-info.pl shows (some) status info of the battery charger state
• /etc/pmic-config.sh configures the PMIC with more liberal charger settings. Invoked at startup by /etc/systemd/system/pmic-config.service.