CN201138879Y - LED control circuit - Google Patents

Abstract

The utility model relates to an LED control circuit, comprising LED1 and LED2 to be controlled, the anode of a bypass diode D1 is connected to the anode of LED1, the cathode of diode D1 is connected to the cathode of LED2; the anode of LED1 is connected to VDD, and the cathode of LED2 is connected to The ground terminal, and the cathode of LED1 and the anode of LED2 are commonly connected to an I/O port P1 of the microcontroller. A resistor R1 is connected between the LED1 and the VDD, and a resistor R2 is connected between the LED2 and the ground. The structure of this control circuit is simple, and the I/O ports in the single-chip microcomputer are effectively used, which can be set to three different states: high level, low level and high-impedance state, so that one I/O port realizes two The control of four states of LED can reduce the system design cost.

Description

LED control circuit

technical field

The utility model relates to an LED control technology, in particular to an LED control circuit.

Background technique

LED (light-emitting diode) light-emitting diode is a very commonly used display device in the control system, as an indicator of various functions and beautify the appearance.

The control of LED often uses microprocessors such as single-chip microcomputers to output high and low levels through the single-chip microcomputer to control the corresponding LEDs to be all bright and all off. In the traditional control method, each LED controlled by the same I/O port of the single-chip microcomputer is on or off at the same time. Although the LED can be blinked by outputting high and low alternating levels, there are few controllable states, which are too rigid and difficult to control. To achieve the effect of partly bright and partly not bright.

Utility model content

The technical problem to be solved by the utility model is: to provide an LED control circuit, which is simple and can control more states, thereby simplifying the system and reducing the system design cost.

In order to solve the above-mentioned technical problems, the utility model adopts the following technical scheme: a LED control circuit, including LED1 and LED2 to be controlled, the positive pole of a bypass diode D1 is connected to the anode of LED1, and the negative pole of diode D1 is connected to the cathode of LED2; LED1 The anode of LED2 is connected to VDD; the cathode of LED2 is connected to the ground terminal, and the cathode of LED1 and the anode of LED2 are connected to an I/O port P1 of the microcontroller.

Preferably, a resistor R1 is connected between the LED1 and the VDD, and a resistor R2 is connected between the LED2 and the ground.

The beneficial effects of the utility model are: the control circuit is simple in structure, and effectively utilizes the I/O ports in the single-chip microcomputer to be set to three different states: high level, low level and high resistance state, thereby using an I The /O port realizes the control of the four states of the two LEDs, namely: LED1 is lit, LED2 is not lit; LED2 is lit, LED1 is not lit; both LED1 and LED2 are off; alternately lit at a certain frequency LED1 and LED2 make use of the persistence effect of human vision to make human eyes feel that both LED1 and LED2 are in a bright state. The system design cost can be reduced by adopting the control circuit.

Below in conjunction with accompanying drawing, the utility model is described in further detail.

Description of drawings

Fig. 1 is a schematic diagram of the LED control circuit of the present invention.

Detailed ways

Please refer to FIG. 1 , the utility model provides an LED control circuit, which can use one I/O port of a single-chip microcomputer/microprocessor to realize the control of two LEDs.

The specific circuit structure is as follows: LED1 and LED2 to be controlled are connected in series, and the anode of a bypass diode D1 is connected to the anode of LED1; the cathode of diode D1 is connected to the cathode of LED2; the anode of LED1 is connected to VDD, and LED1 and A resistor R1 can also be connected between VDD; the cathode of the LED2 is connected to the ground terminal, and a resistor R2 can also be connected between the LED2 and the ground terminal; and the cathode of the LED1 and the anode of the LED2 are commonly connected to an I/O of the microcontroller Port P1. Resistors R1 and R2 are used as current-limiting resistors, and their specific parameters can be selected according to the circuit and actual requirements.

In the specific control, a total of four control states can be realized:

1) When the I/O port P1 is at low level, LED1 is lit, and at this time LED2 has no current flowing and will not light up;

2) When the I/O port P1 is at a high level, LED2 is lit, but at this time LED1 has no current flowing and will not light up;

3) When the I/O port P1 is in a high-impedance state, LED1 and LED2 are bypassed by the parallel diode D1 at this time, and neither LED1 nor LED2 will light up;

4) When the I/O port P1 performs continuous switching between high and low levels with a duty cycle of 50% at a certain fixed frequency, the human visual persistence effect is used to make the human eyes feel that both LED1 and LED2 are bright status.

The structure of this control circuit is simple, and the I/O ports in the single-chip microcomputer are effectively used, which can be set to three different states: high level, low level and high-impedance state, so that one I/O port realizes two The control of four states of LED can reduce the system design cost.

Claims (2)

1. A LED control circuit, comprising LED1 and LED2 to be controlled, characterized in that: the anode of a bypass diode D1 is connected to the anode of LED1, the cathode of diode D1 is connected to the cathode of LED2; the anode of LED1 is connected to VDD, and the anode of LED2 The cathode is connected to the ground terminal, and the cathode of LED1 and the anode of LED2 are jointly connected to an I/O port P1 of the microcontroller. 2. The LED control circuit according to claim 1, wherein a resistor R1 is connected between the LED1 and the VDD, and a resistor R2 is connected between the LED2 and the ground.