BeagleBone Black GPIOs

Adafruit has a ton of tutorials for the beaglebone black. They even have their own Python library. <a href="https://learn.adafruit.com/category/beaglebone" rel="nofollow">https:&#x2F;&#x2F;learn.adafruit.com&#x2F;category&#x2F;beaglebone</a><p>Derek Molloy has several video tutorials: <a href="http://derekmolloy.ie/beaglebone/" rel="nofollow">http:&#x2F;&#x2F;derekmolloy.ie&#x2F;beaglebone&#x2F;</a><p>Both of these resources have just about all of their source available on Github.<p>Anyone whose done &quot;little&quot; embedded will be absolutely amazed by embedded linux, once they can get a base level of proficiency. With smaller processors, every bit of functionality in the code is there either because you had to put it there yourself, or you cobbled it together from 7 different barely tested libraries. If those libraries are any good, you may have paid thousands of dollars each, plus 20% every year, for an RTOS, Ethernet, TCP&#x2F;IP, USB, filesystem, etc. Oh, whats that? You want to switch from Freescale to Texas Instruments? Fuck you, pay me. You want to release two different products with the same RTOS? Fuck you pay me. You want multiple developers using the same libraries? Fuck you pay me.<p>With a beaglebone black, for free, immediately and in perpetuity, you have TCP, UDP, HTTP, FTP, DHCP, SSH, SPI, I2C, UART, Filesystems, SDMMC, USB host and device, HDMI, Threads, Processes, Semaphores, Pipes, Queues, Python, Java, C&#x2F;C++, Android, MySQL, and more. Additionally, just about all of these features have been thoroughly tested because its all Linux. There are more questions and answers on Google&#x2F;StackOverflow, because there are more Linux developers to chime in. Even if they&#x27;ve never touched a beaglebone, most of their experience is still relevant. You can program, compile, and debug directly on the processor, without needing an IDE or JTAG debugger. It&#x27;s truly an amazing device&#x2F;experience.

I&#x27;m using the BeagleBone Black as the platform for my GoBalloon [1] project. Overall, it&#x27;s awesome: the GPIO and UART ports work as expected. One major annoyance, however, is the lack of easy-to-use DC input current sensor. For my battery-powered project, I want to be able to monitor the supply voltage that the BBB is getting. I want to read this value in software so I can do things like reduce the telemetry transmission rate if the battery starts to run low. I also want to log the supply voltage so that I can compare the performance of different battery technologies on subsequent flights.<p>I was chatting with the folks on freenode:#highaltitude and it turns out there is a way to do this, but it involves soldering jumper wires onto pins of the BBB&#x27;s Power Management Controller and pulling resistors off the PCB. Yuck. I decided to use a INA219 on my custom cape instead. Hacky.<p>Thanks for the writeup on the device tree overlays. That&#x27;s going to be super useful for me.<p>[1] <a href="https://github.com/chrissnell/GoBalloon" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;chrissnell&#x2F;GoBalloon</a>

I love the BeagleBone Black and I own several of them. I also bought some for work. But I hate setting them up. I wasted days getting one to boot again, after an update made booting from uSD impossible. Setting up the GPIO pins and the PRUs (programmable real time units) is a pain in the behind, because the set-up-method keeps changing. The article mentions device tree overlays, which are relatively new, but these were actually thrown out of the latest Ubuntu builds. And don&#x27;t get me started on uEnv.txt. For beginner&#x2F;intermediate users, this is suboptimal.

Tangential to the core topic of the post, it mentions problems with the RaspberryPi&#x27;s USB and Ethernet, referencing a 2-year-old Slashdot Post.<p>I&#x27;ve never encountered real issues with my RasPi, but I really haven&#x27;t used it significantly. Nevertheless, that&#x27;s a long time to have issues with popular hardware.<p>Have the USB problems been since corrected? What about the model B+, which upgrades the USB controller from the LAN9512 to the LAN9514: <a href="https://learn.adafruit.com/introducing-the-raspberry-pi-model-b-plus-plus-differences-vs-model-b/usb-ports-hub" rel="nofollow">https:&#x2F;&#x2F;learn.adafruit.com&#x2F;introducing-the-raspberry-pi-mode...</a> ?

Thank you, this is very helpful for people who are experienced with embedded work, but unfamiliar with the BBB. I wish I had this available a couple of months ago, when after figuring things out on my own, I also ended up writing an I2C library (something I never expected would be necessary, it&#x27;s called LsquaredC).<p>Platforms like the BBB and RPi have a lot of beginner-level tutorials, but as soon as you try to do anything out of the ordinary (PWM a pin, or issue repeated I2C start), you end up on your own.

Nice article, but why does every post about the BeagleBone have to include a swipe at the Pi?

Another great feature of the BBB GPIO pins is that you can map some of them to a register on the PRU. Since the PRU runs at 200Mhz, this gives you some really impressive real-time capability. The sysfs technique the article outlines is definitely convenient, but latency can be high, as much as 1ms. Mmaping the GPIO controller and using some real-time extensions to the kernel can get that down to a few us, but using the PRU can take it down to a handful of ns.<p>The PRU is the unrecognized gem of the BBB. As long as you&#x27;re not scared of assembly :).

Good overview, as someone who&#x27;s worked with the BeagleBone Black a bit it&#x27;s nice to see a single blog post that covers lower level GPIO access comprehensively like this one does.