I'm attaching a 3.3v wifly to my maple, to save adding another vreg into my circuit, I was wondering if there is a regulated output I should use from the maple, or can I simply create an output pin in my setup:
#define wiflyPin 21
void setup()
{
digitalWrite(wiflyPin, HIGH);
}
Then just plug it into ground. Wifly only draw 20 or 30mA so this would be ideal. Thanks!
mmmm so maybe I should be running it off a separate 3.3v feed. I thought the maple could supply up to 300mA with Vin regulated to near 3.3v. I'm using an external variable voltage regulator which is quite difficult to get to sit on 3.3v exactly so I was a bit dubious about plugging that directly into the wifly. Trying to find a 3.3v vreg that supplies up to 300mA has been harder than I thought. So powering through the maple seemed more logical.
robodude666
Member
Are you using the WiFly Shield, or the WiFly breakout board? There's an important difference for you between the two. The WiFly Shield also includes the SC16IS750 SPI to UART IC which will add a few more mA of current draw.. Nothing significant, but keep it in mind.
Also, please be aware that the Maple has two 3.3v regulators onboard. While advertised to output 500mA, it's really 250mA per regulator.
The WiFly module is advertised to consume 15mA on standby, 40mA on idle/RX, and 140 - 212mA on TX. If you look at the WiFly Shield schematic, there's a separate voltage regulator onboard that converts VIN to 3.3v... I think you should do the same. If you are using the WiFly Shield, you won't have to worry about it - just make sure VIN is connected to the maple's VIN!
I really would recommend adafruit's adjustable powersupply or if you want a standalone component, sparkfun sells a LD1117V33. Both are low-voltage dropout regulators, so you'll expect a +/- 1% accuracy. Keep in mind that the WiFly module is happy to accept 3.0 to 3.7 V, but it would prefer 3.3 V.
If you are against using a separate power supply for the WiFly, at least have it powered by VCCA - that's the supply that's being used as the analog reference voltage. You'll get slightly less accurate ADC readings, but at least you won't stress the main VCC regulator -- since it's also powering the Maple and the status blinky!
-robodude666
The regulator is is one of the reasons we actually forked the hardware.
https://github.com/soycamo/maplebacon
We are using an x1117 based regulator which puts out between 800ma and 1a depending on how much you want to loose in the ldo.
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