HiJack power questions

Products & Technology Others
#1

I have a couple questions about the HiJack, and was wondering if you could help me.

The wiki page (http://www.seeedstudio.com/wiki/index.php?title=Hijack) says that it can supply 7.4mW of power. Is this the power the unit can supply to an external sensor/peripheral? Or is it the total power harvested for use by the microcontroller + sensors?
Does this leave enough power to drive the TI MSP430, and data communication?
The wiki also notes that “Because of the energy harvest mode, the sensor power draw in this kit should not exceed 5mW.” Does that mean that the microcontroller needs at least 2.4mW to function?
I have a product idea that would need 1-2 milliamperes of DC current for an external circuit. According to the voltage (2.8v) and power (5-7.4mW) specs available through HiJack, I figure that I would have between 1.78 - 2.64mA of maximum DC current available. Is that correct?
Can the power output (current) be adjusted easily via an app using the libHiJack? Does the adjustment of power come from the microcontroller on the HiJack, or by adjusting the volume of the phone?

#2

hi,thanks for you interesting on hijack. the 7.4mW means the power can be used by external sensor caculated by theory. it is suggested no more than 5mW for the system stationary. and, the adjustment of power is via adjusting the volume of the phone.

#3

I just got my HiJack, and was testing it with my iPhone 4. The voltage output is right at 2.755V. But when I measure the current output in my circuit, I get 8.42mA. That would mean the power output is like 23mW. That doesn’t seem right. Seems like I’m getting a lot more power than I should. What’s up?