Skip to main content
Topic: Free PCB build + EEPROM written to death :) (Read 7911 times) previous topic - next topic

Free PCB build + EEPROM written to death :)

I started building the Flash Destroyer after I received the free PCB, but I had to put the project on hold due to some other high priority tasks and lack of some of the parts :)

The most expensive parts of this project were the 7-segment displays. I had a lot of different 7-segment displays in my junkbox, but most of them are not single digit. I didn't want to spend about £1 a digit for Kingbright's displays, so I headed to eBay for a quick search. I found these for about £3 shipped for 10 displays:

http://www.ebay.co.uk/itm/NEW-10-X-0-56 ... 335bfba94c

The part number of these displays is SM42056-1K and according the datasheet they are suitable replacement. These displays are a little bit taller and wider then the Kingbright's, but eventually fitted nicely on the PCB :)

After the PCB was built, I plugged the poor 24AA01-I/P into the socket and turned the power on.

This picture I took the moment I turned the power on, but due to my slow reaction and the shutter lag, some 500 cycles elapsed in an instant:

[attachment=3]

Then I left the poor boy sitting there and counting, counting ...

After 13 days elapsed, the counter was still ticking and the EEPROM survived over 7 million writes. I wanted to capture the precious moment of the display showing all 7s, but again I had no luck:

[attachment=2]

Event though I put the camera in burst mode, the speed was not sufficient to capture the exact moment. The photo before this one captured 7777762.

Then again I left the destroyer doing its job.

After 19 days since the start, I found the poor EEPROM had died:

[attachment=1]

I'm not sure where I got the firmware source from, but it seems it was an older version, because after the 10 million writes the display didn't show a dot but reverted to all 0s again. So in fact the total number of the writes the chip survived was about 11.4 million.

[attachment=0]

After the EEPROM had died, I played a bit with the sources and made the display capable of showing all alhpa-numeric characters (some were not that readable, but it is hard to represent some letters with only 7 segments :)

Now I'm working on re-purposing the Flash Destroyer into a digital thermometer. I will post my success (if any) here soon.

Re: Free PCB build + EEPROM written to death :)

Reply #1
The datasheet of 24AA01-I/P from microchip says more than 1 million cycles.
Nice to see it survived more than 11 million cycles. Microchip may need now to revise datasheet and should say that more than 10 million cycles.
Still learning
-Arup

Re: Free PCB build + EEPROM written to death :)

Reply #2
Nice, thank you for the update. Did you get a kit or a free PCB?

It is interesting you got about the same as Ipenguin and I.

Quote
The datasheet of 24AA01-I/P from microchip says more than 1 million cycles.

That is at voltage and temperature extremes. In an oven at 5.5volts it will last 1million, but under ice at 3.3volts it could last 20+million :) It seems at room temperature it lasts around 11million from the reports we have gotten.
Got a question? Please ask in the forum for the fastest answers.

Re: Free PCB build + EEPROM written to death :)

Reply #3
Ian,

I've got the free PCB only from the Free PCB Sunday about a year ago (6th June to be precise ;)

Most of the parts I already had in my junkbox, only the missing displays delayed the completion of this project.


The 11 million writes seems to be consistent at room temperature (it was around 25 degrees Celsius here all the time).

Re: Free PCB build + EEPROM written to death :)

Reply #4
25 seems nice :) I hope to keep the shop 18-20 year round, if energy isn't too expensive ;)
Got a question? Please ask in the forum for the fastest answers.

Re: Free PCB build + EEPROM written to death :)

Reply #5
Yeah, the room keeps this temperature all the summer, despite the fluctuations from 10 - 25 outside. Even during the winter it seldom falls below 18 inside (if I forget to turn the heating on :)

So it seems my electrical appliances are lucky - working at the specified temperature sweetspot ;-)

Re: Free PCB build + EEPROM written to death :)

Reply #6
Hi, It looks like you all live in cold areas. :P
Here in my area it's 10-15 in winter and 40-45 in summer. Quite tough!
Still learning
-Arup

 

Re: Free PCB build + EEPROM written to death :)

Reply #7
Quote
40-45 in summer. Quite tough!

Maybe :) In Hawaii I lived in 25-28 all year, perfect, I bought all my clothes and shoes at a drug store (Longs Drugs for the west-coasters). In Iowa it is -30c (winter) to +48 (summer), basically the worst of everything, and I hate it ;) I would always take warm all the time, but obviously it is personal preference. I have also lived in Amsterdam. The weather is always 0c-23c, but it rains all the time and the days are only 4-5hours long in the winter (depression inducing).
Got a question? Please ask in the forum for the fastest answers.

Re: Free PCB build + EEPROM written to death :)

Reply #8
Amsterdam sucks ;)