How to connect the reed switch sensor to the microcontroller

ccclllc'z'c

How to connect the reed switch sensor to the microcontroller [Copy link]

 

Microcontroller meter reading problem, water meter and gas meter use reed switch sensor, how to transmit the signal to the microcontroller? What type of signal? How should the meter output pulse?

littleshrimp

The reed switch is equivalent to a switch or button. One end is connected to the power or ground, and the other end is connected to the gpio. External or internal pull-up and pull-down resistors

ccclllc'z'c

littleshrimp posted on 2019-2-23 21:41 The reed switch is equivalent to a switch or button. One end is connected to the power or ground, and the other end is connected to the gpio. External or internal pull-up and pull-down resistors

I just learned about microcontrollers. What is gpio? Can the reed switch be directly connected to the I\O port of the microcontroller? Do I need shaping and filtering?

littleshrimp

ccclllc'z'c posted on 2019-2-23 21:54 I just started to learn microcontrollers. What is gpio? Can the reed switch be directly connected to the I\O port of the microcontroller? Does it need shaping and filtering?

You can just treat it as a button.

ccclllc'z'c

Is shaping filtering required?

ccclllc'z'c

littleshrimp posted on 2019-2-23 22:08 You can just treat it as a button

How does the meter output pulses? Is there a special pulse output port?

littleshrimp

ccclllc'z'c posted on 2019-2-23 22:14 How does the meter output pulses? Is there a special pulse output port?

I checked online and found that reed switches are used for flow statistics. Timers are needed for meter reading communication. You should also look at the specific meter model if you are not the designer of the meter.

bigbat

I have heard of and seen reed switches, but I don't know what this "reed switch sensor" you mentioned is. Reed switches are used in machinery to make magnetic switches. Can you give me more details?

qwqwqw2088

In 51 programming, the connection method of the reed switch is the same as that of the button. If the button program can be used, the reed switch can also be used

ddllxxrr

The reed switch is a switch. Let's think about how to connect the switch to the microcontroller.

chunyang

The reed switch contact is a pure mechanical switch, which is used exactly the same as the push button switch and can be directly connected to the IO. It is best to connect one end to the ground and the other end to the IO, and then add a pull-up resistor to the power supply. The software processing should add anti-shake delay.

ccclllc'z'c

chunyang posted on 2019-2-24 15:19 The reed switch contact is a pure mechanical switch, which is used exactly the same as a push button switch and can be directly connected to IO. It is best to connect one end to the ground and one end to the IO, and then to the power supply...

What kind of pulse does the reed switch transmit?

ccclllc'z'c

bigbat posted on 2019-2-24 08:38 I have heard of and seen reed switches, but I don't know what this "reed switch sensor" you mentioned is. Reed switches are used in machinery to make magnetic switches...

I want to use a microcontroller to read three meters, but I don't know what sensor can get the pulses of the three meters.

tiankai001

It has been made very clear before that the reed switch is equivalent to a push switch. The push switch will jitter when it is pressed and released, and the reed switch will also jitter, so it needs to be de-jittered. When used in three-meter meter reading, the reed switch and the magnet are usually used in pairs (of course, this is an early three-meter pulse detection method, and now there are more sampling methods.) Generally, a magnet is added to a certain position on the mechanical counting wheel of the three-meter, and then a reed switch is installed at the bottom of the counting wheel. When the counting wheel rotates, the reed switch is attracted by the magnet once for each rotation. One end of the reed switch is grounded, and the other end can be connected to VCC through a resistor. The end of the resistor connected to the ground is connected to the microcontroller port (that is, GPIO).

tiankai001

I forgot to mention the debouncing of the reed switch. As for the debouncing of the reed switch, a timer can be used to debouncing. If the timer is set to 1 second, then the number of seconds for which the reed switch is continuously closed can be detected to be considered as a confirmed closing, which can be used as a counting pulse. Of course, there are many details to be considered in the specific implementation.

zhuyebb

I'm just passing by to buy soy sauce

tiankai001

ccclllc'z'c posted on 2019-2-23 21:54 I just learned about microcontrollers, and I want to ask what gpio is? Can the reed switch be directly connected to the I\O port of the microcontroller? Do I need shaping and filtering?

gpio means general purpose I/O port, which is the input and output port of the microcontroller. The reed switch can be directly connected to the I/O port of the microcontroller, and it needs to be debounced, or it can be debounced using software

tiankai001

ccclllc'z'c posted on 2019-2-25 10:07 What kind of pulse is transmitted by the reed switch?

You can refer to the waveform of key jitter

chunyang

ccclllc'z'c posted on 2019-2-25 10:07 What kind of pulse does the reed switch send out?

For a single excitation, the closing and opening process of the reed will oscillate. On the waveform, the corresponding closing and opening edges are sawtooth-shaped.

ccclllc'z'c

tiankai001 posted on 2019-2-26 10:15 You can refer to the waveform of key jitter

Thanks, big guy