![]() ![]() If I start to wave my hand, starting with a small movement and then increasing, I see this plot.Īs you can see the hand movement causes an immediate effect on the output of the second OpAmp, but the value has to go above (or below) a threshold before the digital output triggers The STM32F103C8 has an anlogue input range of 0 to 4096 (12 bit) ![]() Green is the digital output (in this case its LOW / OFF), and the Red trace is the analog signal, which is close to half the 3.3V Vdd voltage supplied to the board. Looking at the output when nothing is moving I see this plot The reason I’m writing values of 0 at the beginning of the line of output and 4500 is because the Arduino IDE “Plotter” feature is auto ranging, and if I don’t include a lower an upper bound, the vertical scale constantly changes I then wrote a very simple sketch in the Arduino IDE to print both the analogue signal from 2Out and also the normal digital output from the boardīTW. My RCWL 9196 board is not exactly the same as this, but the pinout of the IC is the same.Īlso the RCWL 9196 is almost identical to the BIS0001 (Schematic from Joe Desonnet’s github account) The pin I connected to is Pin 12 on U1, (RCWL 9196 and is the output of the 2nd OpAmp in that chip). The main difference in my approach is that I have connected a wire from the analogue signal output on the only IC on the board, into an analogue input on a STM32F103C8 (aka Blue Pill) board. I hope to have taken this at least one step forward with my tests. Where the properties of these devices was explored. This github site contains loads of useful information on these boards, and there is also an excellent video by Andreas Spiess on YouTube The boards I bought use the RCWL 9196, but appear to have identical functionality to those with the RWCL-0516 chip on them A new type of “Radar” motion sensor has been getting a lot of attention in the last couple of months, but no one seemed to know how they worked, so I decided to buy a few of these very cheap devices (sub $1) and investigate possible methods of operation. ![]()
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