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Category: Hardware

2017-02-17

This update has been a while in the making. Between the last update and this one I accidental adopted a dog. That little shit machine has been a time sink. The Hardware Portion So anyways, the previous objective was to interface the NASA quality 4-20mA current loop simulator with the BBB. Several related and unrelated issues had to be address A bit tangential, but the GPIO pins are high when the BBB is first turned Read more…


2017-01-18

The 4-20mA current loop simulator is done. Pictures of the finished product below. Most of the parts I had on hand, but did have to buy a regulator (Texas Instruments LM317L) and a 500 Ohm 0.5 Watt pot. The pot was a shocker – approx $12. I usually buy quantity 10 of whatever I order just to have it on hand, but this was an exception.   The above was designed (and boy do I Read more…


2017-01-10

Starting dabbling with creating the schematics for the project. Tried several open source 2D CAD packages. I think I’m going to stick with QCAD (https://qcad.org/en/). The most important feature that sets it apart from other free CAD packages I’ve tried is the distinct lack of corrupting of drawings and loss of said drawings. I’m definitely going to have purchase a “pro” license to support development. This is really my first foray into drawing circuits. I’m Read more…


2017-01-08

The Software So the next goal for this project was to get the BBB (Beagle Bone Black) to be able to drive digital output and to setup the reading of values from a 4-20mA current loop. Googling on configuring a GPIO pin to output with pull down resistors sent me down the rabbit hole of Device Tree overlays, kernel drivers, subsystems, SysFS, and so forth. Spent two days in the fuckery that is Linux documentation Read more…