A TENS device for transcutaneous electrical nerve stimulation wraps around the upper calf much like a wristwatch wraps around the wrist. Here are some of its operational secrets. A medical device called a Quell performs what’s called transcutaneous electrical nerve stimulation on the lower leg. This technique is said to relieve diabetic pain. None of […]
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Debouncing switches in hardware and software
A switch can be wired to a digital input on a microcontroller (MCU), but the switch contacts can mechanically bounce together and apart a few times within milliseconds before finally closing. It’s also common on relays and solenoids that pull heavier current than PCB-mounted electronics and is sometimes called “chatter” because you can hear the […]
Reference design covers wearable heart-rate and pulse-oximetry apps
This optical heart-rate module reference design incorporates red and infrared LEDs, a sensor, power subsystem, and logic level translation. Measuring 13mm x 13mm, this tiny, low-power board can be placed on a finger or earlobe to accurately detect heart rate and SpO2 via personal wearable devices. The module works with both Arduino and ARM mbed […]
