CN211531383U

CN211531383U - LED positive and negative scanning circuit

Info

Publication number: CN211531383U
Application number: CN201922443102.1U
Authority: CN
Inventors: 李振钦; 张涛; 万利; 邓伟文; 项方
Original assignee: Foshan Pdskyline Electronics Technology Co ltd
Current assignee: Foshan Pdskyline Electronics Technology Co ltd
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-09-18
Anticipated expiration: 2029-12-27

Abstract

The utility model discloses a LED positive and negative scanning circuit, which comprises an MCU, a first scanning circuit and a second scanning circuit, wherein the MCU comprises a public port and at least one scanning port; the first scanning circuit comprises at least one forward LED branch, one end of each forward LED branch is connected to the common port, and the other end of each forward LED branch is connected with different scanning ports respectively; the second scanning circuit comprises at least one reverse LED branch circuit, one end of each reverse LED branch circuit is connected to the common port, and the other end of each reverse LED branch circuit is connected with different scanning ports respectively; the arrangement directions of the LEDs in the forward LED branch circuit and the reverse LED branch circuit are opposite. Adopt the utility model discloses, can move the LED in the forward LED branch road before, change again public port and the level height of scanning port, further drive the LED in the reverse LED branch road, can reduce occuping of MCU's port resource, improve the advantage of product.

Description

LED positive and negative scanning circuit

Technical Field

The utility model relates to a LED scanning field especially relates to a positive and negative scanning circuit of LED.

Background

In the field of LED driving, I/O port resources of the MCU will be used. The currently used technical solutions include static scanning and dynamic scanning. Assuming that 4 LED lamps are controlled, at least 5I/O ports are required if a static driving manner is used, as shown in fig. 1; if the dynamic scan mode is used, at least 4I/O ports are required, as shown in FIG. 2. However, at present, the competition of the home appliances is more and more intense, the performance is required to be achieved, the cost is also required to be controlled, and the cost is required to be low, so most of microcontrollers used by small home appliances are 8-bit MCUs, but 8-bit MCU chip resources are very tight, and port resources need to be reasonably allocated, so that the occupation of I/O port resources is urgently needed to be further reduced, the cost is reduced, and a favorable situation can be obtained in the field of more and more intense competition of home appliances.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a LED positive and negative scanning circuit is provided, can solve the many difficult problems of the required IO port resource of LED drive among the prior art.

In order to solve the above technical problem, the utility model provides a LED positive and negative scanning circuit, including MCU, first scanning circuit and second scanning circuit, MCU includes a public port and at least one scanning port; the first scanning circuit comprises at least one forward LED branch, one end of each forward LED branch is connected to the common port, and the other end of each forward LED branch is connected with different scanning ports respectively; the second scanning circuit comprises at least one reverse LED branch circuit, one end of each reverse LED branch circuit is connected to the common port, and the other end of each reverse LED branch circuit is connected with different scanning ports respectively; the arrangement directions of the LEDs in the forward LED branch circuit and the reverse LED branch circuit are opposite.

Preferably, the first scan circuit is connected to the common port through a first current limiting resistor.

Preferably, the second scan circuit is connected to the common port through a second current limiting resistor.

Preferably, the forward LED branch is provided with a first diode which is connected in series with the LED and is arranged in the same direction.

Preferably, the first diode is a switching diode.

Preferably, the reverse LED branch is provided with a second diode which is connected with the LED in series and has the same arrangement direction.

Preferably, the second diode is a switching diode.

Implement the utility model has the advantages that:

the utility model provides a positive and negative scanning circuit of LED can move the LED in the forward LED branch road before, changes again the level height of public port and scanning port further drives the LED in the reverse LED branch road, can reduce occuping of MCU's port resource, improves the advantage of product.

Drawings

FIG. 1 is a prior art LED static scan circuit diagram;

FIG. 2 is a prior art LED dynamic scan circuit diagram;

fig. 3 is a block diagram of a forward and backward scanning circuit of an LED provided by the present invention;

fig. 4 is a circuit diagram of an implementation of the forward and backward LED scanning circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings. It is only noted that the invention is intended to be limited to the specific forms set forth herein, including any reference to the drawings, as well as any other specific forms of embodiments of the invention.

As shown in fig. 1, the conventional LED static scan circuit diagram is based on the following principles: the MCU inputs fixed levels at two ends of the LED, can keep display unchanged, and updates the output of the MCU only when the number to be displayed needs to be changed. That is, when COM1 is set to low level and SEG1, SEG2, SEG3, and SEG4 are set to high level, LEDs 5 to LEDs 8 are all lit, otherwise, all are not lit. Driving four LEDs requires 5I/O ports.

As shown in fig. 2, the conventional LED dynamic scan circuit diagram is based on the following principles: the MCU needs to scan each LED regularly, the total scanning time does not exceed 20ms, each LED scans in turn, only one LED can be displayed each time, but all the LEDs are still sensed to be displayed simultaneously due to the phenomenon of human visual persistence. That is, when COM1 is set to low and COM2 is set to high, SEG1 is set to high and SEG2 is set to low, LED2 scans the display; when COM1 is set to low and COM2 is set to high, SEG1 is set to low and SEG2 is set to high, LED1 scans the display; when COM1 is set to high and COM2 is set to low, SEG1 is set to low and SEG2 is set to high, LED4 scans the display; when COM1 is set high and COM2 is set low, SEG1 is set high and SEG2 is set low, LED3 scans the display. Driving four LEDs requires 4I/O ports.

As shown in fig. 3, the present invention provides a block diagram of a forward and backward LED scanning circuit, which includes an MCU1, a first scanning circuit 2 and a second scanning circuit 3, wherein the MCU1 includes a common port a and at least one scanning port (b, c, etc.); the first scanning circuit 2 comprises at least one forward LED branch 201, one end of each forward LED branch (201, 202, etc.) is connected to the common port a, the other end of each forward LED branch is respectively connected with different scanning ports (b, c, etc.), namely, the forward LED branch 1 is connected with the port b, and the forward LED branch 2 is connected with the port c, and is connected according to the specific branch number according to the rule; the second scanning circuit 3 comprises at least one reverse LED301 branch, one end of each reverse LED branch 301 is connected to the public port (a, etc.), the other end of each reverse LED branch is respectively connected with different scanning ports (b, c, etc.), namely, the reverse LED branch 1 is connected with the port b, the reverse LED branch 2 is connected with the port c, and the reverse LED branches are connected according to the specific branch number; the setting directions of the LEDs in the forward LED branch and the reverse LED branch are opposite, for example, the positive electrode of the LED in the forward LED branch is connected to the common port a, and the negative electrode of the LED in the reverse LED branch is connected to the common port.

It is specified that the positive electrodes of the LEDs in the forward LED branch are connected to the common port a, and the negative electrodes of the LEDs in the reverse LED branch are connected to the common port. When the public port a is set to be at a high level, the scanning port b is set to be at a high level, and the scanning port c is set to be at a low level, the reverse LED branch circuit 2 is conducted; when the public port a is set to be at a high level, the scanning port b is set to be at a low level, and the scanning port c is set to be at a high level, then the reverse LED branch circuit 1 is conducted; when the common port a is set to be at a low level, the scanning port b is set to be at a low level, and the scanning port c is set to be at a high level, the forward LED branch 2 is conducted; when the common port a is set to be at a low level, the scanning port b is set to be at a high level, and the scanning port c is set to be at a low level, then the reverse LED branch circuit 1 is conducted. Therefore, the MCU is used for adjusting the level of the ports a, b and c, the LED can be scanned in a segmented mode, the whole scanning period is generally set to be 500us, the flicker frequency of the 10ms LED lamp cannot be identified based on human eyeballs, and the scanning period can be suitable for product requirements. Adopt the utility model discloses, four LEDs of drive need 4 IO ports.

As shown in fig. 4, in order to implement the circuit diagram of the present invention, the MCU includes a common port COM and at least one scan port (SEG1, SEG 2.). The first scanning circuit comprises at least one forward LED branch, one end of each forward LED branch is connected to the common port COM, and the other end of each forward LED branch is respectively connected with different scanning ports (SEG1, SEG 2.); the second scanning circuit comprises at least one reverse LED branch circuit, one end of each reverse LED branch circuit is connected to the common port COM, and the other end of each reverse LED branch circuit is respectively connected with different scanning ports (SEG1, SEG 2.); the LED9 and the LED10 are arranged in the same direction, and the direction is opposite to the arrangement direction of the LED11 and the LED 12.

It should be noted that, the utility model provides a positive and negative scanning circuit of LED, LED9 and LED10 in the forward LED branch road can be moved earlier, change again the level height of common port COM and scanning port (SEG1, SEG 2..) further drives LED12 and LED11 in the reverse LED branch road, can reduce the occupation of MCU's port resource, improves the advantage of product.

Preferably, the first scan circuit is connected to the common port COM through a first current limiting resistor R1, and the second scan circuit is connected to the common port COM through a second current limiting resistor R2. The current limiting resistor is used for protecting the LED and the MCU and preventing the LED and the MCU from being burnt out.

More preferably, the forward LED branch is provided with a first diode (D1, D2..) in series with the LED and in the same direction. Further, the first diode is a switching diode. The switch diode is used for protecting the LED and preventing the LED from being burnt out. In a similar way, the reverse LED branch is provided with a second diode which is connected in series with the LED and has the same setting direction, and further, the second diode is a switch diode.

To sum up, the utility model provides a positive and negative scanning circuit of LED can move the LED in the forward LED branch road before, changes again the LED in the reverse LED branch road of further drive is advanced to the level height of public port and scanning port, can reduce occupying of MCU's port resource, improves the advantage of product. Meanwhile, the MCU and the LED are protected through the current-limiting resistor and the diode.

The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and decorations can be made without departing from the principle of the invention, and these modifications and decorations are also regarded as the protection scope of the present invention.

Claims

1. An LED forward and backward scanning circuit is characterized by comprising an MCU, a first scanning circuit and a second scanning circuit, wherein the MCU comprises a public port and at least one scanning port;

the first scanning circuit comprises at least one forward LED branch, one end of each forward LED branch is connected to the common port, and the other end of each forward LED branch is connected with different scanning ports respectively;

the second scanning circuit comprises at least one reverse LED branch circuit, one end of each reverse LED branch circuit is connected to the common port, and the other end of each reverse LED branch circuit is connected with different scanning ports respectively;

the arrangement directions of the LEDs in the forward LED branch circuit and the reverse LED branch circuit are opposite.

2. The LED forward-reverse scan circuit of claim 1, wherein the first scan circuit is connected to the common port through a first current-limiting resistor.

3. The LED forward-reverse scan circuit of claim 1, wherein the second scan circuit is connected to the common port through a second current-limiting resistor.

4. The LED forward-backward scanning circuit of claim 1, wherein the forward LED branch is provided with a first diode connected in series with the LED in the same direction.

5. The LED forward-reverse scanning circuit according to claim 4, wherein the first diode is a switching diode.

6. The LED forward-backward scanning circuit of claim 1, wherein the backward LED branch is provided with a second diode connected in series with the LED and arranged in the same direction.

7. The LED forward and reverse scanning circuit of claim 6, wherein said second diode is a switching diode.