Near field communication device

Abstract

A near-field communication device includes an antenna unit, a rectifier unit, a load unit, a light-emitting diode (LED) unit, and a microcontroller. The rectifier unit is electrically connected to the antenna unit to receive an AC voltage signal and convert it from AC to DC to output a DC voltage signal. The microcontroller is electrically connected to the rectifier unit, the load unit, and the LED unit. Upon startup, it controls a load resistor in the load unit to conduct to a ground terminal, detects the magnitude of the DC voltage signal to obtain a measured voltage, and calculates an actual usable power value. When the microcontroller determines that the actual usable power value is greater than or equal to a predetermined threshold, it controls the LED unit to emit light to indicate a corresponding normal state.

Claims

1. A near-field communication device, comprising: an antenna unit for receiving an electromagnetic wave signal from a near-field communication card reader to generate an AC voltage signal; a rectifier unit electrically connected to the antenna unit for receiving the AC voltage signal and converting the AC voltage signal into AC-DC to output a DC voltage signal; a load unit electrically connected to the rectifier unit for receiving the DC voltage signal and controlled to determine whether to conduct the DC voltage signal to a ground terminal via a load resistor; a light-emitting diode unit controlled to determine whether to emit light; and a microcontroller electrically connected to the rectifier unit, the load unit, and the light-emitting diode unit, receiving the DC voltage signal as an operating power source, and upon startup, controlling the load resistor of the load unit to conduct to the ground terminal, detecting the magnitude of the DC voltage signal to obtain a measured voltage, calculating the measured voltage multiplied by the measured voltage divided by the resistance value of the load resistor to obtain an actual usable power value, and then controlling the load resistor of the load unit not to conduct to the ground terminal. When the microcontroller determines that the actual available power value is greater than or equal to a predetermined threshold, it controls the light-emitting diode unit to emit light to indicate a corresponding normal state. The near-field communication device also includes an electronic paper display, which is electrically connected to the rectifier unit and the microcontroller, receives the DC voltage signal as its operating power, and is controlled by the microcontroller to display an image. When the predetermined threshold corresponds to the DC voltage signal as the operating power of the electronic paper display, the electronic paper display is controlled by the microcontroller to update the image normally.

2. The near-field communication device as claimed in claim 1, wherein, When the microcontroller determines that the actual available power value is less than the predetermined threshold, it controls the light-emitting diode unit to emit light to indicate a corresponding abnormal state.

3. The near-field communication device as claimed in claim 1, wherein, The light-emitting diode unit includes a first light-emitting diode and a second light-emitting diode capable of emitting different colors of light. The microcontroller can control the first light-emitting diode and the second light-emitting diode to emit light, respectively corresponding to the normal state and the abnormal state.

4. The near-field communication device as claimed in claim 1, wherein, The load unit includes a load resistor and a switching element. The load resistor includes a first terminal and a second terminal electrically connected to the rectifier unit to receive the DC voltage signal. The switching element includes a first terminal electrically connected to the second terminal of the load resistor, a second terminal electrically connected to the ground terminal, and a control terminal electrically connected to the microcontroller. When the logic value of the control terminal of the switching element is equal to a first logic value, the first terminal and the second terminal of the switching element are not connected. When the logic value of the control terminal of the switching element is equal to a second logic value, the first terminal and the second terminal of the switching element are connected.

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