https://purinda.com/tags/beaglebone/ Recent content in beaglebone on Purinda Gunasekara Hugo en-AU Mon, 11 Aug 2014 08:40:17 +1000 https://purinda.com/posts/fatal-cannot-locate-cpu-mhz-in-proccpuinfo/ Sun, 10 Aug 2014 23:51:30 +1000 https://purinda.com/posts/fatal-cannot-locate-cpu-mhz-in-proccpuinfo/ <p>This became a problem for my Raspberry Pi (armv6h) running Archlinux (with a relatively newer kernel). Some users of my Grooveshark server reported some bufferring problems where it stopped streaming songs and reported “FATAL: cannot locate cpu MHz in /proc/cpuinfo”.</p> <p>Since the Grooveshark server is based on Qt5 I thought the new Qt5.3 version had some multimedia library changes that caused the issue, but turned out the issue is /proc/cpuinfo not producing CPU frequency for the ARM based CPUs. But what program is using a proc cpuinfo to determine CPU frequency without getting the value from sys filesystem exposed by the kernel? or using a monotonic clock as per newer kernels, which would provide timing capabilities without depending on system level changes, turned out there are quite a few programs around that depends on the value specified in “cpuinfo” file in proc filesystem. Including “jack” audio server which is a dependancy for QtMultimedia framework and number of other applications.</p> https://purinda.com/posts/multiple-spi-bus-beaglebone/ Mon, 01 Oct 2012 23:23:52 +1030 https://purinda.com/posts/multiple-spi-bus-beaglebone/ <h2 id="how-to-get-spi-to-work-on-beaglebone">How to: Get SPI to work on Beaglebone <a class="anchor" href="#how-to-get-spi-to-work-on-beaglebone" aria-label="Link to this section"></a></h2> <p>If you want just one SPI port running, then most up to date images for beaglebone has enabled them by default.<br> Location to get pre-compiled images with SPI1 enabled, <a href="http://rcn-ee.net/deb/precise-armhf/v3.2.25-psp20/">http://rcn-ee.net/deb/precise-armhf/v3.2.25-psp20/</a></p> <h3 id="enabling-spi0">Enabling SPI0 <a class="anchor" href="#enabling-spi0" aria-label="Link to this section"></a></h3> <h4 id="step-1">Step 1 <a class="anchor" href="#step-1" aria-label="Link to this section"></a></h4> <ul> <li> <p>In order to enable userland SPI we need to be able to rebuild the kernel, so grab the Linux source:</p> https://purinda.com/posts/rf24bb/ Thu, 09 Aug 2012 15:15:45 +0000 https://purinda.com/posts/rf24bb/ <h2 id="why">Why? <a class="anchor" href="#why" aria-label="Link to this section"></a></h2> <p>I started working on a project which require communication with multiple radios. I started looking at nRF24L01 chip and found it to be very useful, cheap little device which has many features built-in. Initially I got two AVRs to talk to each other through the simple library found here (<a href="http://www.tinkerer.eu/AVRLib/nRF24L01">http://www.tinkerer.eu/AVRLib/nRF24L01</a>). But I found multiple issues with the library when the number of nodes in the network increases,</p>