• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Electrical Engineering News and Products

Electronics Engineering Resources, Articles, Forums, Tear Down Videos and Technical Electronics How-To's

  • Products / Components
    • Analog ICs
    • Connectors
    • Microcontrollers
    • Power Electronics
    • Sensors
    • Test and Measurement
    • Wire / Cable
  • Applications
    • Automotive/Transportation
    • Industrial
    • IoT
    • Medical
    • Telecommunications
    • Wearables
    • Wireless
  • Resources
    • DesignFast
    • Digital Issues
    • Engineering Week
    • Oscilloscope Product Finder
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Women in Engineering
  • Videos
    • Teschler’s Teardown Videos
    • EE Videos and Interviews
  • Learning Center
    • EE Classrooms
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
    • FAQs
    • Ebooks / Tech Tips
  • EE Forums
    • EDABoard.com
    • Electro-Tech-Online.com
  • 5G

In defense of the toggle switch

July 31, 2018 By Scott Thornton Leave a Comment

toggle switch

Figure 1: Image of the 1960s-era spacecraft, the Gemini capsule, taken at the Pacific Science center in Seattle, Washington. The module control panel has several toggle switches.  (Image credit: Ryan Somma)

The world has gotten much fancier with capacitive and resistance touch input on displays, buttons that don’t give tactile feedback, or buttons that do but bounce the input signal on occasion. Buttons are everywhere. They’re on microwaves, refrigerators, garage door openers, smartphones, and inhabit the soul of the electric start/stop for modern automobiles. For designers, developers, experimenters, hobbyists, programmers, and plain old engineers, the designs surrounding buttons have gotten more complicated. The consequences of button behavior are up to us. For example, using a garage door remote can be tricky. The first press of the button and you might not be in range. The second time you press it, you might not realize that it’s already begun and press it a third time, causing it to reverse direction.

The electric start/stop on my new-ish hybrid Toyota is another example. After nearly two years of driving it, I still cannot determine what the series of beeps mean when I press the start/stop button, especially when I leave the car. Sometimes it’s telling me that I pushed it too few times and the car is still on but in accessory mode. At other times, it seems to be trying to tell me that the fob is still in the car when it’s actually in my pocket and on the way out of the car. But I have to stop and check the touchscreen display, which is sometimes difficult to read in bright sunlight. It’s even more fun when my spouse is driving the car and I forget that the fob is in my pocket. I usually dash off before it starts beeping in very much the same way as the “your car door is open” warning.  (Turns out you can still drive the car without the fob, but you cannot restart it once you turn it off.) However, it’s annoying to have to stop what you’re doing and determine what beeping means when a simple ignition switch is a definite known state when leaving a car.

In defense of the humble toggle switch, once it’s flipped, it’s real status is visible and dependable.

You can send button status and the input from many devices over communications busses like SPI and I2C, or over plain old I/O pins, but regardless of the distance traveled, communications over SPI and I2C is not 100% error free. If you have an input device that uses SPI or I2C, such as a DAC or an ADC, the best scenario is to have a way to check the reliability of the signal, such as with a checksum in the protocol. Or a DAC could have a serial output pin so you can verify the data that it’s receiving and digitizing.

If these methods for ensuring ongoing reliability are not available, you will have an error at some point, albeit infrequently (depending on how many times the MCU communicates with the connected ADC/DAC/other device). The error can last for as long as it takes to overwrite the erroneous data, which can be milliseconds or days. You do need to consider the consequences of the rare but possible incidence of incorrect data if you do not have some means to read back or check the data sent over a communications protocol that could be susceptible to noise, dirty power, or what-have-you. If you have bounce in an input device, you can end up with a repeated input. If you do not have any tactile feedback, it’s possible that someone could hit the button twice. In some design cases, duplicate input may not matter. Some duplicate input can cause a redo of a process that is expensive to re-do.

The glory days of toggle switches, such as what populated early space travel the Gemini capsules, are over. Toggle switches are just not as sleek and elegant as capacitive touch input or buttons with a membrane cover, but in some cases, buttons are still used for critical functions, especially in areas like space flight.

DesignFast Banner version: 03e1dd97

Filed Under: FAQ, Featured, Microcontroller Tips Tagged With: FAQ

Reader Interactions

Leave a Reply Cancel reply

You must be logged in to post a comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Primary Sidebar

EE Training Center Classrooms

EE Classrooms

Featured Resources

  • EE World Online Learning Center
  • CUI Devices – CUI Insights Blog
  • EE Classroom: Power Delivery
  • EE Classroom: Building Automation
  • EE Classroom: Aerospace & Defense
  • EE Classroom: Grid Infrastructure
Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

R&D World Podcasts

R&D 100 Episode 7
See More >

Current Digital Issue

Our second 5G Handbook is now available

Featuring 15 articles, the 2022 5G Handbook looks at private networks, timing, connectivity, latency, mmWaves, test, and other topics.

Digital Edition Back Issues

Sponsored Content

Positioning in 5G NR – A look at the technology and related test aspects

Radar, NFC, UV Sensors, and Weather Kits are Some of the New RAKwireless Products for IoT

5G Connectors: Enabling the global 5G vision

Control EMI with I-PEX ZenShield™ Connectors

Speed-up time-to-tapeout with the Aprisa digital place-and-route system and Solido Characterization Suite

Siemens Analogue IC Design Simulation Flow

More Sponsored Content >>

RSS Current EDABoard.com discussions

  • Photovoltaic MOSFET Drivers - Voltage Rating
  • UCC28070A controller ramp circuit implemented incorrectly?
  • Timing question on RX code
  • Frequency of FM transmitter not changing
  • Altium Routing: through vias being split into two blind vias. Additional question about blind via costs / benifits

RSS Current Electro-Tech-Online.com Discussions

  • software PWM
  • 200mv pulse to 12v lock
  • Background of Members Here
  • UCC28070A ramp circuit is wrong?
  • Treadmill board component burn repair

Oscilloscopes Product Finder

Footer

EE World Online

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • Electro-Tech-Online Forums
  • Engineer's Garage
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • Wire & Cable Tips

EE WORLD ONLINE

  • Subscribe to our newsletter
  • Lee's teardown videos
  • Advertise with us
  • Contact us
  • About Us
Follow us on TwitterAdd us on FacebookConnect with us on LinkedIn Follow us on YouTube Add us on Instagram

Copyright © 2022 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy