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The point of the twisted pair is to have a signal and its return on the pair. Using the two halves of a pair for an unrelated signal is an unintended use, and the tight twist of the two halves together leads to severe crosstalk, as you've experienced. Consider using a microcontroller at the remote end, and a differential signal such as RS-422, to communicate ...
8
Since you probably don't need ultra snappy response to the buttons, I'd first try adding simple RC filters to the switch lines. Ideally on the microcontroller side but I think you'd still get benefit on the switch side. You're getting cross talk because when the switch triggers it snaps the line to ground with a sharp edge. That sharp edge has a lot of high ...
6
As others have suggested, you may do some encoding on the far end, and transmit differential signals down the cat5e cable. An alternative that relies upon this being a human interface, and consequently low data rate, is to use DTMF, the signaling method for land-line touch-tone telephones. You can get a DTMF encoder for about $5 from reputable sources, and a ...
4
I had a somewhat similar issue about 4 years ago, sorta. I was running CANbus over about 250 ft of CAT5. Everything was running fine while the cable was coiled up in the box (the kind bulk cable comes in). At installation things went weird and the signal was becoming intermittent. That was solved by slowing the transmission speed down considerably. However ...
4
Building on answers and comments that others have mentioned: The cross talk will be manageable if you have enough debounce. Say, 0.5 sec. The internal pullup is too high a resistance for that distance. I'd recommend a max of 1k for that distance. Also, at the arduino, make sure to use a ceramic capacitor at the input (0.1 uF) to take out interference. If ...
4
You could also use a pair for power/ground to power three differential pair drivers (perhaps 3/4 of a AM26LS31) on the far side to make 7 possible combinations and have each switch transmit a unique binary digit to be decoded at the Arduino via a differential pair receiver with 100-ohm terminators. You'll have to do a little diode logic but the Vih of the ...
2
Connecting the microprocessor pins to the outside world is shaky at best. You need to use some sort of interface to clean up the signal and isolate the micro from the outside world. A simple voltage divider shown below will do the trick. Feed the switch with a higher voltage such as 12V if you have it. The top of the voltage divider goes to the button, the ...
2
It depends what voltage you want to deliver to the thermistor. Remember you need to drive the base of the BJT about 0.6 or 0.7 V anniversary the emitter. So if you only want to power the thermistor with 2.5 or 3.3 V, then you have no problem. But if you want to deliver the full 5 V to the thermistor, then you need to find a way to provide 5.6 V or so to the ...
2
The tools you have available to you don't really know from rows and columns. Assuming the file isn't strictly formatted to the point that you know how many characters in the data you are looking for is, I suggest reading one character at a time in a loop, counting new line characters until you're on the right line. Then, read the next line, saving to a ...
2
250 feet and directly into an unprotected micro input? Ahh, might want to rethink that! Microprocessor IO should nearly never be directly exposed to the outside world (I say nearly because there are some cases where it is hard to avoid). Were I drawing this, I might keep your one button per wire thing that same (No real reason not to), but the doings at the ...
1
You could do something like this: simulate this circuit – Schematic created using CircuitLab Adjust trimpot R9 to get the output voltage just above 0V with the minimum usable setting on the input R8. The gain is 100K/R2 = 33.3, so the output will be from (say) 200mV to 3.5V for the input from R8 from 2-3V. Single 5V supply is okay. The LM324 has 4 ...
1
If your Bench-top-power-supply (i.e. your DC power supply) has current indicator, read that current. Or, measure the current, on the main power, 12V input. Put the AC power adapter (Wall Wart), that you are using now, in your reserve container, and get a new, at least 1.5x current rated, AC power adapter. Meantime measure the 12V output, while loading, read ...
1
No it has no effect other than spending time printing those status strings.
1
Make sure that the Arduino itself is being powered properly. I was attaching Arduino Uno to a nearly out of battery laptop via USB cable, resulting in a jittering servo. As soon as I've put the laptop on charge, the servo started working smoothly!
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