Method of transmitting information from a card reader with a power supply and wake-up circuit to a mobile device

1. A method of transmitting information to a mobile device, comprising:

providing a card reader with a read head that has a slot for swiping a magnetic stripe of a card, the card reader including wake-up electronics that detect when the card is being swiped in the slot, signal a microcontroller to put the device electronics into an active mode from a sleep mode and power down the wake-up electronics when the device electronics is in the active mode, and a power supply coupled to the wake-up electronics and the microcontroller;

reading data on the magnetic stripe;

producing a raw magnetic signal indicative of data stored on the magnetic stripe;

converting the raw magnetic head signal into a processed digital signal that the microcontroller can interpret; and

sending an output jack signal to the mobile device.

2. The method of claim 1 , wherein the card reader includes an analog to digital front-end, the analog to digital front end being coupled to a processing element in the microcontroller.

3. The method claim 1 , further comprising:

producing an encrypted output jack signal.

4. The method of claim 1 , further comprising:

producing an encrypted and signed output jack signal.

5. The method of claim 1 , further comprising:

producing a synchronous Manchester encoded stream output jack signal.

6. The method of claim 1 , further comprising:

producing an asynchronized stream output jack signal.

7. The method of claim 1 , further comprising:

producing an output jack signal at a frequency that the output jack signal appears to look AC to a microphone input of the mobile device.

8. The method of claim 1 , further comprising:

producing an output jack signal at a frequency of 2 KHz to 48 kHz.

9. The method of claim 1 , further comprising:

capturing card readings at the analog to digital front end that are swept at a rate of 5 inches to 50 inches per second.

10. The method of claim 1 , further comprising:

sending the output jack signal to the mobile device at a constant baud rate.

11. The method of claim 10 , wherein the constant baud rate is 2400 to 9200 baud.

12. The method of claim 1 , wherein the analog to digital front end includes, an amplifier/filter, differentiator, a comparator and wake-up electronics.

13. The method of claim 12 , further comprising:

using the wake-up electronics to signal the microcontroller, which in turn puts the device electronics back into the sleep mode when a card swipe signal stops.

14. The method of claim 13 , further comprising:

powering the wake-up electronics by a microphone bias of the mobile device.

15. The method of claim 13 , further comprising:

detecting by the wake-up electronics when there is an edge from leading zeros of a card being swiped and alerting to wake up the microcontroller and device electronics.

16. The method of claim 13 , further comprising:

waking up the device electronics in enough time to process and encrypt a card swipe signal.

17. The method of claim 1 , wherein the device electronics includes an amplifier/filter, differentiator, comparator, transmission electronics, and the microcontroller.

18. The method of claim 17 , further comprising:

amplifying the raw magnetic signal by the amplifier/filter and processing before the microcontroller accepts it as an input.

19. The method of claim 18 , further comprising:

taking the output of the amplifier/filter by the differentiator and differentiating it to look for peaks in the input signal.

20. The method of claim 19 , further comprising:

using the comparator to take the output of the differentiator and compares it to a reference voltage and produces an output that is a processed digital version of a magnetic swipe.

21. The method of claim 20 , further comprising:

using the comparator to look for where an input signal crosses zero.

22. The method of claim 21 , further comprising:

using the microcontroller to accept the comparator input; and processing the comparator input and encrypting at least a portion of data of the comparator input.

23. The method of claim 17 , further comprising:

using the microcontroller to control power to the amplifier/filter, differentiator and comparator.

24. The method of claim 17 , further comprising:

using the transmission electronics to accept output data of the microcontroller as an input and using this to modulate a microphone-bias line of the mobile device.

25. The method of claim 24 , further comprising:

using the microphone-bias line for power and data transmission back to the mobile device.

26. The method of claim 1 , further comprising:

using the microcontroller to convert raw bit patterns into formatted credit card information.

27. The method of claim 1 , further comprising:

using the microcontroller to independently determine if swiped card data is valid.

28. The method of claim 1 , further comprising:

accepting motion of the card bi-directionally in the slot.

29. The method of claim 1 , further comprising:

accepting motion of the card at varying velocities as the card is swiped through the slot.