A long time ago, I made a video suggesting math was unnecessary to determine proper pull-up resistor values. Like most generalized statements, that suggestion is not always true. For example, in data buses like I2C, speeds like 400 kHz and 1 MHz are common. At those speeds, the pull-up resistor and the bus capacitance form an RC filter that fundamentally limits the data transmission speed. Or. It limits the range of pull-up resistor values. In this Workbench Wednesdays video, I show how to estimate I2C bus capacitance, measure that capacitance, and pick pull-up resistor values.

Everything with a microcontroller has serial buses in it. Busses like UART, I2C, and SPI are very popular choices. When you have a problem with a sensor that uses one or the bus itself, you can use an oscilloscope or logic analyzer to “decode” the traffic. These decoders convert the 1s and 0s into readable HEX or ASCII characters.

I am not sure how I thought of the “multiple” James idea for the thumbnail. The concept had something to do with “serial,” but I am not sure what.

Anyway, my favorite James is the far left one. He has no idea where the camera is at.

Oh and this picture was done without a green screen. I took multiple shots of me standing in different spots and then composited them together.

If you need a reason to be an Element 14 member, let me suggest their Road Test program. Companies partner with Element14 to get people to try out their gear. A couple of years ago I got a new microcontroller board. This week I received a new test instrument. Here’s my hands-on Picoscope 2204 review.

The scope is bus powered. With the BNCs and type-B USB connector, it is slightly larger than an external USB hard drive. There is not much weight to the device. It does not feel cheap, just lighter than I expected.

Getting the scope up and running is a breeze. Pico Tech included a CD (or DVD?) to install the software, but I could not find my drive to check it out. Software downloads from Pico Tech’s website work great. It looks like you can even download the software and use it in “Demo mode” if you are curious how it works–without purchasing anything.