The Reed Switch Module provides a logic output when a magnetic field comes near or is removed.
- Reed Switch Module
KEY FEATURES OF REED SWITCH MODULE:
- Outputs logic HIGH or LOW depending on if magnetic field is near
- 3.3 and 5V compatible
This is a SPST Reed Switch module. Reed switches are mechanical switches which are a activated by a magnet when the magnetic field pulls the switch contacts together. Real world uses include applications such as home security where a reed switch is placed in proximity to a magnet when a window is closed. If the window is opened, the magnet moves away from the switch that causes it to change states which can then be detected by an MCU.
The module has a SPST reed switch with NO (Normally Open) contacts until a magnet comes into close proximity to the glass envelope and then the switch contacts are closed.
The D0 output is normally LOW and will transition to HIGH when a magnet comes near. The A0 output is normally HIGH and will transition to LOW when a magnet comes near.
There are 2 LEDs on-board. A red LED lights when power is applied. A second red or green LED lights when the reed switch is activated.
There is a 4-pin header on the assembly for making connections. The ‘A0’ pin is a misnomer in this application as it is a digital output that is the inverse of the ‘D0’ pin.
1 x 4 Header
- A0 = Digital output active LOW. connects to digital input on MCU
- GND / G = Ground
- ‘+’ = 5V
- D0 = Digital output active HIGH. Connects to digital input on MCU
OUR EVALUATION RESULTS:
These modules are useful for evaluating basic reed switch functionality.
Since the sensor is a mechanical switch that inherently has 2 states ON/OFF, so what is normally an analog output (A0) on these types of modules is still just a digital output. For the same reason, the potentiometer has little effect on the output. That output does provide the complementary output of the D0 output which may be useful in some applications such as if the module is being used to directly drive a relay or something similar.
If it is desired to measure the strength of a magnetic field rather than detect its presence, the Analog Hall Effect sensor is a better option to consider.
The glass envelop enclosing the reed switch sensor can be broken if twisted, so use care if adjusting the position of the sensor.
BEFORE THEY ARE SHIPPED, THESE MODULES ARE:
- Sample inspected and tested per incoming shipment
|Vcc||3.3 – 5V|
|Dimensions||L x W (PCB)||36 x 15mm (1.4 x 0.60″)|
|L x W (PCB w/ sensor)||42 x 20mm (1.7 x 0.8″)|