Peter Farley's personal blog
Recently, I’ve come into possession of a decent quantity of several microcontrollers. One of these were a bunch of MSP432E4’s. Not a chip I would normally choose to use for a project (being that it does not support Zephyr (and TI’s library has some bugs), and is quite expensive), but you can’t beat the price of free. Plus it has a decent number of peripherals, including a MAC+PHY with PTP support…
Well, it’s been over two years from the last post, but I guess better late than never.
A while back I installed a GPS-disciplined PTP (Precision Time Protocol) time server at home. This was partially due to a contract project that was using PTP (but totally did not require having such a dedicated time server), but mostly just because I am interested in time. On most of my hard-wired machines I already have them set up to use PTP as their time source (everything else will be using…
Finally I’ve come to the most complex part of the Sigfox (ignoring the standard PC motherboard) - the SDR (Software Defined Radio). I had originally intended to only get a high-level block diagram of this part, but I ended up going a lot deeper than I planned, and have a good amount of it reverse-engineered. I left out a lot of the power circuitry, and there are some parts I didn’t bother tracing…
As I’ve been working on reverse-engineering the SDR module from the Sigfox base station, I also wanted to dump any ROMs from the device. The audio interface chip was easy, since it had an external SPI flash that could be dumped with flashrom or another tool. The microcontroller on the board was less straightforward, however. It was a Freescale HCS08 which didn’t use an industry-standard debug…
Before moving on to the more complex SDR module, I decided to take a look at the external LNA (low noise amplifier) first. This has some similarities to the power amplifier I covered in the previous post, except that this amplifies received signals and lives near the antenna, rather than inside the base station.
Now that I’ve given an overview of the Sigfox base station, I’ll start diving deeper into the individual components. I’ll start here with the RF Power Amplifier, denoted as BPA (Base station Power Amplifier, perhaps? But it’s also possible it could include French words as that is where Sigfox is based) on the PCB. This is the last stage outgoing signals pass through on the way out of the base…
Over a year ago I obtained a Sigfox base station, or TAP (Transfox Access Point), from a company that was moving and wanted to get rid of some of their old equipment. Sigfox operates a LPWAN (Low-Power Wide-Area Network), more-or-less as a competitor to LTE Cat. M/NB-IoT or LoRaWAN. I don’t think it ever achieved widespread adoption (in my experience - admittedly US-centric with a little…
GitHub repo containing the PCBs and 3D models in this post: https://git.pfarley.dev/pfarley/tek-tla-probes
Back in 2015, Linux deprecated the /sys/class/gpio interface in favor of using other methods to access GPIO pins. It’s been over 8 years since then, and the interface is still around, and thus some systems still make use of it. Many of these are fairly easy to change to use pre-existing drivers suck as gpio-leds or gpio-keys, at least on systems that use device-tree. Other use cases can be solved…
This is a project that I started a bit over a year ago, though which is still in progress at the time of writing. There are two GitHub repos associated with it: PCB designs: https://git.pfarley.dev/pfarley/keithley-615-printer-boards Firmware: https://git.pfarley.dev/pfarley/keithley-615-net-fw
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