Hi,
I'm going to start a project but I am not sure if Flora is the right platform for it...but I try to build it as small as possible.
Can a flora handle
- Flora Wearable Ultimate GPS Module
- Adafruit 10-DOF IMU Breakout - L3GD20H + LSM303 + BMP180
- Monochrome 1.3" 128x64 OLED graphic display
- MicroSD card breakout board+
All powered with a Lithium Ion Polymer Battery - 3.7v 1200mAh battery.
Is the Flora powerful enough to run those components together?
Cheers
Oliver
Is Flora powerful enough?
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Please be positive and constructive with your questions and comments.
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adafruit_support_mike
- Posts: 67485
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Re: Is Flora powerful enough?
Yeah, that should be fine. The Flora uses the same microcontroller as the Leonardo, so it's on the same general level as the Uno.
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OliverS
- Posts: 8
- Joined: Wed Nov 12, 2014 7:30 pm
Re: Is Flora powerful enough?
Thanks...that's great!
One more question:
What's the best way to shut sensors and display down (sleep mode)?
I know I can use pull EN on the GPS, but is there a way to turn OLED and sensors off to safe power?
One more question:
What's the best way to shut sensors and display down (sleep mode)?
I know I can use pull EN on the GPS, but is there a way to turn OLED and sensors off to safe power?
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adafruit_support_mike
- Posts: 67485
- Joined: Thu Feb 11, 2010 2:51 pm
Re: Is Flora powerful enough?
The OLED and sensors don't have an official 'low power' mode, so you'd have to remove power to shut them off.
The IMU doesn't present much of a current load even when it's running.. the gyro wants about 5mA and the others want less than 1mA each.
The OLED uses 20mA-25mA nominal, but the exact current depends on how many pixels are lit.
In theory, you could power the OLED and the IMU from one of the Flora's GPIO pins. Each pin has an upper limit of 40mA and the combined OLED/IMU nominal load is about 25mA-30mA. I'd be nervous about doing that though, since there's always a chance of a sudden load exceeding the pin's limit.
The easy-and-safe way to control power to the OLED and IMU is with a PNP transistor. Put one between the Flora's 3.3v output and the VCC pins for the devices you want to control, and connect a 2.2k resistor between the base and one of the control pins. That will give you plenty of power on the device side, and a load of about 1mA on the control side.
Cutting power does mean you'll have to reconfigure each device every time you reconnect power. As far as the chips are çoncerned, you'll be doing a normal power-up sequence.
One tip for the GPS module: get a battery for it. The battery allows the module to keep its table of information about previous fixes, which it uses to locate the satellites for its next fix. Getting a fix from a cold start can take a few minutes, while getting a fix from battery power usually takes less than 30 seconds.
The IMU doesn't present much of a current load even when it's running.. the gyro wants about 5mA and the others want less than 1mA each.
The OLED uses 20mA-25mA nominal, but the exact current depends on how many pixels are lit.
In theory, you could power the OLED and the IMU from one of the Flora's GPIO pins. Each pin has an upper limit of 40mA and the combined OLED/IMU nominal load is about 25mA-30mA. I'd be nervous about doing that though, since there's always a chance of a sudden load exceeding the pin's limit.
The easy-and-safe way to control power to the OLED and IMU is with a PNP transistor. Put one between the Flora's 3.3v output and the VCC pins for the devices you want to control, and connect a 2.2k resistor between the base and one of the control pins. That will give you plenty of power on the device side, and a load of about 1mA on the control side.
Cutting power does mean you'll have to reconfigure each device every time you reconnect power. As far as the chips are çoncerned, you'll be doing a normal power-up sequence.
One tip for the GPS module: get a battery for it. The battery allows the module to keep its table of information about previous fixes, which it uses to locate the satellites for its next fix. Getting a fix from a cold start can take a few minutes, while getting a fix from battery power usually takes less than 30 seconds.
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OliverS
- Posts: 8
- Joined: Wed Nov 12, 2014 7:30 pm
Re: Is Flora powerful enough?
What a great and detailed answer!
Thank you :)
Thank you :)
Please be positive and constructive with your questions and comments.