Don’t use Grove?   Here is an adaptor to pin headers:  Grove to Pin Header Adaptor

The difference between the normal (0042) and the NE (0043) version of this board is the sense of the ENABLE Line.   It is active high for the 0042 board and active low for the NE (0043) board.

This code is taken from SmartPlantPi, a Raspberry Pi based plant watering system.

First you set up the GPIO pins you are going to use:

         USBControl = 16
         USBEnable = 19

         GPIO.setup(USBEnable, GPIO.OUT)
         GPIO.setup(USBControl, GPIO.OUT)
         GPIO.output(USBEnable, GPIO.HIGH)

To turn the USB on , you just have to follow this design pattern :

  
         GPIO.output(USBControl, GPIO.HIGH)

USB PowerControlNE Board

First you set up the GPIO pins you are going to use:

         USBControl = 16
         USBEnable = 19

         GPIO.setup(USBEnable, GPIO.OUT)
         GPIO.setup(USBControl, GPIO.OUT)
         GPIO.output(USBEnable, GPIO.LOW)

To turn the USB on , you just have to follow this design pattern :

         GPIO.output(USBControl, GPIO.HIGH)

This board was initially designed to sit in-between a Solar Power Controller (such as SunAir/SunAirPlus) and a Raspberry Pi / Arduino.   The LIPOBATIN input to the board was designed to come directly from a LiPo battery so the computer won’t be turned on until the LiPo battery was charged up above 3.8V.  We provide a hysteresis circuit so the board won’t turn off until the voltage goes below around 3.3V.  This is an excellent board to shut on and off USB powered devices like a Raspberry Pi and Arduino.  It works just like a conventional relay, except that it requires virtually no current to keep it on or off.   Like a latching relay.

The USB PowerControl Hysteresis circuit on LIPOBATIN is based on a TA75S39 Operational Amplifier used as a comparator.  A comparator with hysteresis has two important thresholds: upper and lower. Unlike a simple comparator, however, the output of the comparator doesn’t depend solely on whether the input is above or below one of these thresholds. It depends on both the current state of the output and the current value of the input. If the output is high, it will stay high until the input voltage drops below the lower threshold. If the output is low, it will stay low until the input voltage rises above the upper threshold.

The diagram to the right shows a hysteresis ‘loop’ that describes how a comparator functions. The horizontal ‘X’ axis is the input, and represents the difference of the two input voltages. The vertical “Y” axis represents the comparator’s output state.

If the comparator is initially ‘OFF’, the MINUS input voltage has to become slightly above the PLUS input voltage before the comparator output turns ‘ON’. This is represented by moving right along the bottom part of the loop.

Once the comparator is ‘ON’, the MINUS input voltage needs to drop slightly below the PLUS input voltage before it turns ‘OFF’ again (moving left along the top of the loop).

The ‘ON’ state is set in the USB PowerControl to be 3.8V and the ‘OFF’ state is set to be about 3.3V.   The output of the comparator drives the input to the Load Switch.