They are commonly used in inexpensive wireless devices to control garage doors, fans, toys and even some alarm systems. SCM4 — 4 latched data bits There are several versions of these chips, identified by different suffixes, that pass through different amounts of data 2 to 6 or even no data at all, as well as latched or momentary data presentation. The 4 data bits remain latched in their last state. The more data that is presented, the fewer address leads there are. Each address lead is tri-state — high, low or floating.
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See Figure 1 below. The purchase was just a whim to satisfy my curiosity about this type of PIR sensor. The one that I purchased operates on two 1. Of course mine is in MHz to match my existing r06a receiver. I have uploaded a short video on YouTube where you can see a very short clip of the motion detector transmitting the event that is then received and displayed by my Arduino r06a test setup. The listed specifications also show a shorter battery live for the 9V version than for the 3V version — 6-months versus 1-year.
So take your pick — long battery life or lower cost. Figure 1: Wireless Pet Immune PT PIR Motion Detector As is usually the case with unbranded, inexpensive Chinese electronics, documentation is minimal, critical critical circuit board legends are missing and there are indications of imperfect work.
Than said, as is also usually the case with unbranded, inexpensive Chinese electronics, it works! I was rather flummoxed by the simplest electrical issue — battery polarity. This is in violation of all accepted norms and practices and I was concerned that I would fry the circuit if connected that way. I poked around a little bit trying to verify correct polarity but eventually chanced plugged the batteries into their pockets and flicked on the power switch.
Success — the single startup LED flash occurred followed, after a minute by three blinks indicated motion was detected. This device has a one to two minute delay before it is active. By the way, the external power switch is rather incongruous — I can imagine scenarios where it could be disarmed without motion detection, depending, of course, upon where the sensor was located within a room.
Even more incongruous is an internal tamper switch that is defeated by simply turning off the external power switch. Truly odd! For what it is worth, tripping the tamper switch cause an event message transmission identical to a standard motion detection. The single sheet of instructions contained enough Chinese-style English to identify settings options.
Unfortunately, the both the printed diagram and the circuit board legends were in several cases completely missing. Some experimentation was required to completely identify the correct settings. Figure 2, below, shows my settings. The four data bits are used to identify the sensor — I chose bit D1 low for mine binary Figure 2: PIR Circuit Board I have been doing all of my tests with the antenna collapsed to its shortest length of which, including its internal portion is 80mm plus a circuit board portion of an additional 65mm.
If the antenna were fully extended it would be a mm antenna — about a half wavelength. In any case, it works fairly well. I used the fob to transmit the observed data. Figure 3, below, is of the DSO Nano in use. In this particular measurement I am measuring the duration of a complete digit two pulse train — 3. Figure 4, below, is a close-up. Converting the saved XML to an image is a bit of a challenge.
Fortunately, there is a Windows. MONO failed to run it and while the. It is an amazing little program with all kinds of measuring capability. See Figure below. Per the Princeton Technology datasheet, for the PT to decode correctly the waveform that was received, the oscillator frequency of PT must be 2. However, recalling that the OSC is 2. This tells us that the chart in the PT Princeton Technology datasheet timing chart actually reflects data, not that of the So, I modified the chart for a more correct story.
See Figure 7, below. My actual measurements ranged from 3.
(Electronic Components IC) PT2272-M4 PT2272
See Figure 1 below. The purchase was just a whim to satisfy my curiosity about this type of PIR sensor. The one that I purchased operates on two 1. Of course mine is in MHz to match my existing r06a receiver.
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PT2272 - PT2272 Remote Control Decoder Datasheet