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Connecting an I2C peripheral to Metawear

siddrajputsiddrajput
in Hardware
Hi,

I'm trying to connect an I2C peripheral to the Metawear.
  1. My peripheral requires a 1.8V supply.  Where can we get a 1.8V supply? Do I need to
    use an external regulator?  The maximum
    current required will be 1200uA.
  2.  What’s the maximum peak current the V3v peripheral
    expansion (pin 7) can supply?  My peripheral
    requires a 50mA max. peak current.
Sidd

Comments

  • LauraLaura
    Sidd,

    1. My recommendation is to use an external regulator off of the main battery. By the way, that's a lot of current (you might even need a second battery to power that monster!).

    2. Don't use the 3V expansion pin to power anything more than 1mA. Instead, use the battery + a mosfet through the gpio pin to power your peripheral device.


  • siddrajputsiddrajput
    Hi Laura,

    1. That's 1200uA (microamps) or 1.2mA.  Not quite a monster!
    2. Could I use pin 11 to power my peripheral?  In the product spec it says "Regulated 3V output for high current peripheral."  Could that supply enough current?

    Sidd
  • LauraLaura
    Hey Sidd, 

    1. I work with low power sensors (1mA is a monster for me).
    2. 1.2mA is "safe" enough for the GPIOs so you can feel free to try it. 
    Pin 11 can actually sink/source 300mA but it is PWM only so it doesn't stay on all the time.

    You can try your original setup using pin7 without much risk.

    The SOC actually has a mode to sink/source up to 5mA on the GPIO pins but we haven't enabled it yet (it's on 1mA mode now).
  • Dom_CrispiDom_Crispi
    Hi,
    Im working on a school project and were trying to connected the Am2315 Temperature/Humidity sensor to it. However we are having difficulties using the I2C class and how to proceed to wake up and than read the device because the datasheet is a little complicated to understand. 
    Help would greatly be appreciated!
    Thanks,
    Dom
  • EricEric
    edited March 2016
    You need to make a new thread with your question; your post is completed unrelated to original poster.  Furthermore you'll have to provide more details about your problem.  What have you tried so far?  Which datasheet are you referring to?  What platform are you developing on?
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