One Sensor. Two Functions. Countless Possibilities
For designers, balancing form and function can be an ongoing challenge. To address this issue without skimping on quality, we developed the CSM Series backlit illuminated sensor displays. These capacitive touch buttons provide a host of benefits for OEMs and end-users, including:
- Removing size as a design constraint thanks to a 15.0mm x 15.00mm x 3.20mm footprint
- Simplifying the HMI with color identification and function
- Customizing the interface with optional icons that can be screen printed or etched
- Offering extensive mounting options, including under glass or acrylic sheets, and reverse or surface-mount
- Eliminating a mechanical switch that could wear down over time
However, there are even more benefits that deserve a closer look.
The four prongs, integrated circuit, and internal LEDs work together to:
- Control the LED – a function that provides immediate feedback to the user
- Complete or trigger the desired action – could be signaling a microcontroller or PLC or using a more analog approach to flip a transistor to perform another desired action.
No matter the configuration, our cap touch solution can be connected to perform either, or both functions in a single display on the HMI.
“Traditionally, two areas on the HMI were required to show user feedback — one for the LED/light and one to control the desired action. Or, designers would have to take painstaking measures to combine the two. Our CSM Series bundles both functions into a streamlined cap touch button that can trigger complex events and maintain design simplicity.”
Carlos Ramirez
Senior Designer, VCC
Pair the CSM with Any Configuration for a Sleek Solution
The CSM Series provide many advantages that help streamline production and design, including:
- Immediate user feedback with LEDs
- Design flexibility – combining status indication + device control into a single HMI button
- Extended operating life because no mechanical parts are used
- Ability to customize with bi-color or RGB options
Standard Momentary Switch
To mimic standard momentary switches, the CSM requires an external non-inverting bus/buffer driver connected to its output. This component performs two jobs:
- Handling the load connected to the CSM
- Driving the LED inside the CSM
The output of the buffer/driver will be connected to the input of the component used to handle the actual load. This piece could be a solid-state relay or the coil of a mechanical relay, depending on the configuration. For supply voltages up to 5V, the bus buffer/line driver, 3-state
(74LVC1G125) is a great option with high noise immunity.
The CSM delivers a sleek, intuitive touch button for a modern standard momentary switch aesthetic, like in this smart home dimmer:
Latching Switch
Similar to the standard momentary switch configuration, latching switches require an additional component to help handle the load connected to the CSM and drive the LEDs inside the sensor. A buffer or flip-flop driver is connected to the CSM’s output to handle the tasks at hand.
The buffer/flip-flop’s output will be connected to either the solid-state relay or coil of the mechanical relay, depending on the actual load requirements for the device. For example, the Single D-type flip-flop positive-edge trigger (74LVC1G80) is suitable for ranges of 1.65 V to 5.5. V.
Now, even standard on/off functions can meet the design aesthetics modern consumers expect, like in this speaker:
Microcontrollers and PLCs + CSM Series = Powerful Design Opportunities
Microcontrollers, often called MCUs or MCs, are self-contained microcomputers designed to perform a single or several, automated tasks. These MCUs are used in a range of applications and industries, including:
- Appliances
- Automation
- Automotive
- Consumer electronics
- IoT
- Medical and dental equipment
- Robotics
Programmable logic controllers (PLCs) are more complex and suitable for high-performance applications, such as controlling industrial machinery. VCC’s CSM Series works with MCUs and PLCs to streamline user interfaces and enhance the user experience.
When combined with a PLC/microcontroller, the CSM sensor can provide help trigger multiple events:
- Changing the color of the LED to communicate status
- Turn on a relay to turn on a motor or perform another programmed action
The cap touch buttons use an integrated circuit with four pins that connect to the microcontroller and power relay or photocoupler.
Depending on the application, a power relay or photo relay will be required to trigger the action.
- PCB Power Relay – the G5Q PCB power relay (as an example) delivers excellent switching performance for a variety of loads and is ideal for output applications of control equipment.
- Optocoupler/Photocoupler – options like TLP3825 and TLP3825F photocouplers include a photo MOSFET coupled to an infrared LED. The low on-state resistance and high permissible on-state current make these models suitable for applications where EDM noise would be an issue.
Custom Color Options Provide Additional Design Flexibility
Bi-color
To up the ante, designers can also use multiple colors within a single indicator and enhance the human-machine interaction. Whether you want to use a microcontroller or no, custom bi-color and RGB color combinations can be implemented.
Here’s how the bi-color CSM could work with a microcontroller:
- Green is the ON state – turns green light on and turns motor on
- Red is the OFF state – turns green light off and turns motor off
Red/green is just one example of the bi-color options available when customizing a CSM sensor. Additional color configurations can also be created to meet any need.
Tri-Color / RGB Configurations
Another custom option for the CSM Series is using three colors. In this example, the CSM is used with a microcontroller programmed with three different actions. The CSM output engages with the microcontroller’s input to trigger the event and change the colors to provide user feedback:
- Red is the OFF state for either trigger
- Green is the ON state for M1
- Blue is the ON state for M2
As you can see, the CSM Series empowers OEMs and designers to enhance aesthetics and the user experience with the utmost flexibility and convenience. Simply determine which color(s) and microcontroller/PLC/driver/buffers you’ll need for your specific application.
