Tone-based wake up circuit for card reader

摘要

A card reader for a point-of-sale system that is configured to accept both magnetic strip-type and integrated circuit (IC) chip-type payment cards. The card reader is a component of a point-of-sale system including a portable computing device in communication with the card reader that is configured to present a first graphical user interface (GUI) when a magnetic stripe-type card is detected and a second GUI when an IC chip-type card is detected in the card reader. The card reader comprises a slot configured to receive the payment card, a magnetic reading device and an IC chip reading device. The card reader also includes a discriminator contact disposed within the slot that is configured to conduct across a surface of a metal pad of the IC chip-type card prior to the CI chip reading device making contact with the IC chip.

主权项

1. A computer-implemented method for waking up a card reader connected to an audio jack of a mobile device using a wake up circuit disposed within the card reader, the method comprising:
receiving, at an audio plug of the card reader, a microphone bias signal from the audio output jack of the mobile device; transitioning the card reader to an awake mode in response to a rising edge of the microphone bias signal; transitioning the card reader to a sleep mode using a microprocessor while the microphone bias signal is still present; receiving, at the audio plug of the card reader, an audio input signal from the audio output jack of the mobile device; conditioning the audio input signal to produce a conditioned audio input signal having an amplitude between an amplitude of the microphone bias signal and ground; conditioning the microphone bias signal to produce a conditioned microphone bias signal having substantially half the amplitude of the microphone bias signal; comparing the conditioned audio input signal and the conditioned microphone bias signal to output a third signal using a comparator, the comparator configured to output the third signal having an amplitude substantially the same as the microphone bias signal when the voltage of the conditioned audio input signal is greater than the voltage of the conditioned microphone bias signal; converting the third signal to a fourth signal using an envelope detector, the third signal being a square wave and the fourth signal being a substantially DC voltage signal; and providing the fourth signal to an enable pin of a voltage regulator that is connected to the output of the envelope detector.