hc-sr04low-powermosfetpower
I want to read an ultrasonic sensor data every 10 minutes and expect that the module should be turned off in order to save power.
How do I do this?
I tried with a BC547 and PN2222 transistor but I end up with failure.
Can you please suggest a better method to cutoff power from the module? It has 4 pins (VCC,GND, ECHO,TRIG.)
I think I've found the problem now...
In the U-blox center Configuration View I changed the settings in the section:
RXM (Receiver Manager) from 0-Continuous Mode to 1-Power Save mode.
Now it seems to be collecting points only once every 5 minutes as expected :)
I suggest using high-side switches rather than a low-side switch.
Edit: One high side switch for each power supply.
Something like this: (Edit: x2)
It needs a base resistor for the BJT or use a logic-level MOSFET. R1 could be something like 10K and the base resistor 20K or so. The p-channel MOSFET should be logic level for your conditions. You can find dual p/n channel units in an SO8 that can handle some amperes.
The problem with switching the ground connection (low side switch) is that there are two power supplies on the chip and the inputs will end up biased at some voltage above ground, which may draw unnecessary current and/or be bad for your micro.
You still have to bring the outputs of your micro low or you will drive unnecessary current into the L298 inputs.
Best Answer
Use a P-channel MOSFET eg. AO3401A to cut Vcc. Low to the gate = ON.
simulate this circuit – Schematic created using CircuitLab
Add a 1K resistor series with the TRIG input and make sure that you drive TRIG low before shutting off the Vcc and do not drive it high until after Vcc has been turned on. Also do not drive ECHO high as an output (it should never be an output). Adding another 1K on the ECHO line would not hurt.