10-05-2017, 11:29 PM
(This post was last modified: 10-05-2017, 11:31 PM by MarkHaysHarris777.)
(10-05-2017, 08:08 PM)Catprog Wrote:(10-05-2017, 02:49 PM)MarkHaysHarris777 Wrote:(10-04-2017, 09:28 PM)Catprog Wrote: I am planning to have a shift register control the power and reset buttons.
Do I need a transitor or can I put the output in directly?
The premise of your question makes no sense; please elaborate and explain how you think a shift register might control power and reset buttons .
What I am trying to do is electronic control of the power and reset functions.
IE the actual button will be removed and replaced in some way with the output from the IC
I was questioning the shift register, mostly.
Two things you will want to do; check the datasheet schematic(s) and check the function of the power button and reset button functions; they may surprise you !
A PN2222 or 2N2222 general purpose NPN transistor ( or similar ) can be used in place of the switch , with a gpio pin from another MCU or SBC via 1K resistor to the base of the transistor will work just fine for an electronic switch. Also a 4N35 opto-coupler could be used.
The switch is providing a ground shot; the transistor can do the same thing.
The reset is a hard reset ! not a good thing to do unless you ( or the watch dog ) knows that the system is not functioning; you should not press the reset of a running system !
The power button has both a long and a short press function; and a very long press function. They do not work the way most people expect them to. Do some research.
marcushh777
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please join us for a chat @ irc.pine64.xyz:6667 or ssl irc.pine64.xyz:6697
( I regret that I am not able to respond to personal messages; let's meet on irc! )