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Post by Telemachus on Jan 25, 2021 12:23:27 GMT
Cheers. Based on those figures, with the solar panel, I have no worries my batteries would be fine. Good. Anyway, keep us up to date with how you get on.
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Post by patty on Jan 25, 2021 17:19:27 GMT
Raspberry pi sounded like a cookery item..but obviously its not....
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Post by Deleted on Jan 25, 2021 18:37:21 GMT
Raspberry pi sounded like a cookery item..but obviously its not.... It could be a cookery item, I love homemade rhubard crumble...
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Post by Telemachus on Jan 25, 2021 18:41:39 GMT
Raspberry pi sounded like a cookery item..but obviously its not.... No, that would be raspberry pie, not raspberry 3.14159265359... nor raspberry ‘ratio of a circle’s circumference to its diameter’
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Post by patty on Jan 25, 2021 20:29:37 GMT
Raspberry pi sounded like a cookery item..but obviously its not.... It could be a cookery item, I love homemade rhubard crumble... thats one of my fav puddings...
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Post by patty on Jan 25, 2021 20:30:29 GMT
Raspberry pi sounded like a cookery item..but obviously its not.... No, that would be raspberry pie, not raspberry 3.14159265359... nor raspberry ‘ratio of a circle’s circumference to its diameter’ right of all that the only thing I recognise is raspberry pie.....
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Post by Telemachus on Jan 25, 2021 20:45:56 GMT
No, that would be raspberry pie, not raspberry 3.14159265359... nor raspberry ‘ratio of a circle’s circumference to its diameter’ right of all that the only thing I recognise is raspberry pie..... Too late, I ate it.
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Post by Deleted on Jan 26, 2021 10:53:23 GMT
Something else, I guess for Telemachus.
Voltage drop, how far away from the board can a sensor be, presume running at 5v ?
Would I need to go chunky on the cable to get it a decent distance?
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Post by Telemachus on Jan 26, 2021 11:07:34 GMT
Something else, I guess for Telemachus. Voltage drop, how far away from the board can a sensor be, presume running at 5v ? Would I need to go chunky on the cable to get it a decent distance? It depends entirely on the type of sensor and how it communicates (type of interface, and speed). There are three main considerations, voltage drop due to current flow, waveform distortion/rounding due to capacitance and inductance (affected fast communications the most) and spikes/noise introduced from other sources. If you are talking about powering the sensor over a long 5v supply line, again it depends on the current draw. If you give me a clue what sort of sensor you are talking about, I can give more detail.
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Post by Deleted on Jan 26, 2021 11:55:10 GMT
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Post by Telemachus on Jan 26, 2021 12:29:59 GMT
OK so that is just high or low voltage on/off function. The quoted quiescent current seems to be 50uA so I dont think there will be any issues with voltage drop on the 5v supply lines. Maybe it takes a bit more current when it is operating but I would doubt it would be more than a few mA. No need to use fat cable. It appears to have 5v swing on the output so if you are connecting it direct to the Pi there will be an issue with mismatch of operating voltages. I think you mentioned some sort of GPIO interface board, maybe that has some tolerance for higher voltages / level shifting built in, you'd need to check. You also might want to put in some spike protection since if the signal wire is long and unscreened it might pick up transients eg from a fridge thermostat. Input pins on CMOS devices have intrinsic diodes that shunt higher voltage spikes away to the supply, however they are tiny and not designed to sink significant current. One way to add protection is simply to put a 10k resistor in series so that the current from any spike is limited to what the internal diodes can tolerate. Even though these sorts of spikes might only last a few microseconds, the diodes and transistors are microscopic too and can be damaged instantly. But as I said, if you are connecting it through some add-on interface board, that might already have suitable protection. The thing with CMOS is that the gate insulation on the MOSFETS can accumulate damage from spikes, so whilst they can tolerate it occasionally, with repeated accumulation of damage, the transistors can fail.
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Post by Deleted on Jan 26, 2021 14:05:30 GMT
Was going to run with this as a trial.. www.tomshardware.com/how-to/raspberry-pi-pico-motion-sensorOnly difference is I wont be using a bread board, will be using an I/O expansion board. Should all be here this week so will have a play and see what happens, the idea is then to add a 4G hat to the board and then when movement is detected it will send an SMS. Also thinking of building into it a tracker and maybe some other sensors such as temp and water levels in the bilge.
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Post by Telemachus on Jan 26, 2021 14:14:55 GMT
The operating voltage of the Amazon sensor you linked to is 4.5v to 20v. The one in Tom’s Hardware is 3.3v. Important difference!
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Post by Deleted on Jan 26, 2021 14:24:52 GMT
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Post by Telemachus on Jan 26, 2021 14:28:18 GMT
Also its worth mentioning that microPython is an interpreted language, vs say the C++ of Arduino etc that is a compiled language. Interpreted languages have to have bulky run-time software that interprets the code you've written in real time, making it much slower and more power and resource intensive than a compiled language that converts the code to machine language before you load it. Nothing wrong with starting out in microPython since it is very easy and a lot of the techy stuff is done for you behind the scenes, but it is not a particularly good solution for low power embedded control and monitoring systems.
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