Posts with «eeprom» label

Dual-boot Your Arduino

There was a time, not so long ago, when all the cool kids were dual-booting their computers: one side running Linux for hacking and another running Windows for gaming. We know, we were there. But why the heck would you ever want to dual-boot an Arduino? We’re still scratching our heads about the application, but we know a cool hack when we see one; [Vinod] soldered the tiny surface-mount EEPROM on top of the already small AVR chip! (Check the video below.)

Aside from tiny-soldering skills, [Vinod] wrote his own custom bootloader for the AVR-based Arduino. With just enough memory to back up the AVR’s flash, the bootloader can shuffle the existing program out to the EEPROM while flashing the new program in. For more details, read the source.

While you might think that writing a bootloader is deep juju (it can be), [Vinod]’s simple bootloader application is written in C, using a style that should be familiar to anyone who has done work with an Arduino. It could certainly be optimized for size, but probably not for readability (and tweakability).

Why would you ever want to dual boot an Arduino? Maybe to be able to run testing and stable code on the same device? You could do the same thing over WiFi with an ESP8266. But maybe you don’t have WiFi available? Whatever, we like the hack and ‘because you can’ is a good enough excuse for us. If you do have a use in mind, post up in the comments!

Filed under: Arduino Hacks, Microcontrollers

Staring at the Sun: Erasing an EPROM

Flash memory is the king today. Our microcontrollers have it embedded on the die. Phones, tablets, and computers run from flash. If you need re-writable long term storage, flash is the way to go. It hasn’t always been this way though. Only a few years ago EPROM was the only show in town. EPROM typically is burned out-of-circuit in a programming fixture. When the time comes to erase the EPROM, just pop it under an ultraviolet (UV) bulb for 30 minutes, and you’re ready to go again. The EPROM’s quartz window allows UV light to strike the silicon die, erasing the memory.

The problem arises when you want to use an EPROM for long term storage. EPROM erasers weren’t the only way to blank a chip. The sun will do it in a matter of weeks. Even flourescent light will do it — though it could take years.

[TechEkspert] wanted to learn about the nature of erasing an EPROM with the sun, so he got out an old EPROM and started hacking. (translated link) [TechEkspert] programmed the EPROM with a known pattern of ones and zeros. A pair of 74HC4040 counters would address the entire 32 KB memory of the EPROM. An Arduino Mini read the data out, storing it in an SD card. A bit of python code translated the data to PNG files, which were then combined to render a video.

The whole setup was placed on the roof in full sun. Then the waiting began. Nothing much happened for two weeks. Then some bits started to flicker. This means that sometimes they would read as a 0, and other times a 1. The sun was starting to destroy the stored data. Right at the 3 week mark, all the remaining data quickly started to disappear. In the end the entire chip was erased.

While [TechEkspert’s] chip could be re-programmed, that’s not always the case with EEPROM and flash. Check out this EEPROM killer which calculated how many cycles it took to destroy the electronically erasable storage in an Atmel ATmega328.

Filed under: classic hacks
Hack a Day 14 Sep 12:01