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Wafer level chips are cheap and very tiny, but as [Kevin Darrah] shows, vulnerable to bright light without the protective plastic casings standard on other chip packages.

We covered a similar phenomenon when the Raspberry Pi 2 came out. A user was taking photos of his Pi to document a project. Whenever his camera flash went off, it would reset the board.

[Kevin] got a new Arduino 101 board into his lab. The board has a processor from Intel, an accelerometer, and Bluetooth Low Energy out of the box while staying within the same relative price bracket as the Atmel versions. He was admiring the board, when he noticed that one of the components glittered under the light. Curious, he pulled open the schematic for the board, and found that it was the chip that switched power between the barrel jack and the USB. Not only that, it was a wafer level package.

So, he got out his camera and a laser. Sure enough, both would cause the power to drop off for as long as the package was exposed to the strong light. The Raspberry Pi foundation later wrote about this phenomenon in more detail. They say it won’t affect normal use, but if you’re going to expose your device to high energy light, simply put it inside a case or cover the chip with tape, Sugru, or a non-conductive paint to shield it.


Filed under: Arduino Hacks

Many people have their home network setup with a dynamic dns service in order to remote access their files, printers, or Pi based security camera systems. Many people also suffer from less than stellar internet connectivity and find themselves unable to access their home system due to a stalled signal.

netBOOT is an Arduino based device that automatically resets your modem for you, when you are unable to. Core of the system is a standard issue ATMEGA328p based Arduino board combined with a W5100 Ethernet module, and a relay module. The software on the Arduino periodically pings a list of IP addresses and listens for a response. If none is found within 3 tries the relay module, which is connected inline with the DC power of your modem, is clicked open for 10 seconds and then returned closed. Once your modem has rebooted and re-synced everything should be good to go.

We don’t remember seeing this feature in the list of specs for Google’s new OnHub. The ability to reset bad connections seems like a feature that should be built into future-thinking routers, right?

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Filed under: Arduino Hacks, internet hacks, Network Hacks
Feb
17

Zero-wire serial auto-reset for Arduino

arduino, reset, TTL, uart Commenti disabilitati su Zero-wire serial auto-reset for Arduino 

ProMiniAutoReset

Ralph shared his auto-reset feature of his Arduino board. He writes:

Various versions of the Arduino will reset the board by toggling the serial DTR line, a feature called auto-reset. Since it relies on the DTR line, it won’t work with TTL serial adapters that don’t break out the DTR line. After writing my half-duplex serial UART, I thought of using the TTL serial break signal which holds the line at 0V for several ms. Normal serial communications would also send 0V, but at 57.6kbps, it would never last more than 160us before returning to the idle high voltage state. So what I needed was a circuit would not reset when the line is low for 160us, but would reset when the line is low for 100ms or more.

Zero-wire serial auto-reset for Arduino - [Link]



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