I have a netduino plus with a transeiver attached as a SPI-device. The transiever needs to be powered off everytime the netduino is restarted. Is it possible to programatically power off/on the 3V3 pin?
Is it possible to power on/off the 3V3 pin?
Started by Søren Randrup, Mar 23 2012 08:44 AM
6 replies to this topic
#2
Stefan
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Posted 23 March 2012 - 09:05 AM
Hi Søren and welcome to the Netduino Forums,
What you ask is not possible, but you could use a transistor on a digital pin and switch 3V3 with that. That way you can still power on/off the 3V3 pin.
"Fact that I'm a moderator doesn't make me an expert in things." Stefan, the eternal newb!
My .NETMF projects: .NETMF Toolbox / Gadgeteer Light / Some PCB designs
My .NETMF projects: .NETMF Toolbox / Gadgeteer Light / Some PCB designs
#4
Stefan W.
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Posted 23 March 2012 - 07:11 PM
If you truly need 3V3 there, you'd need to use a voltage regulator with an enable/disable input, as a transistor incurs a voltage drop.
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#5
hanzibal
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Posted 26 March 2012 - 01:51 PM
...or you could use a solid state switch, I don't think there's a voltage drop over such a device.
#6
Chris Seto
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Posted 26 March 2012 - 10:33 PM
Best thing to do here is use a MOSFET, which wires up roughly like a transistor.
#7
Mario Vernari
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Posted 27 March 2012 - 03:25 AM
Just add my one-cent...
I'd like to know how much current the device will require, then I'll decide for the best option.
Moreover, switching the supply only might not be enough. Consider that the SPI bus is still wired, and even cutting the device supply, there is current flowing through the SPI bus.
At this point, if the current required is some mA, you could consider a CD4016/CD4066 (or similar). They are solid-state switches (MOSFET), which can be used to cut both the supply and the SPI signals. One chip contains 4 switches, and it costs a bunch of cents.
Cheers
Biggest fault of Netduino? It runs by electricity.
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