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System Building Help

Hi there. I'm new to the embedded world, so I'd appreciate all the help I can get. I've got three analog devices and I'd like to sample them around ~40 Hz each and store that on some type of non-volatile storage. I've got advice from using Stamp kit to purchasing a full-blown "single board computer". But rather than spending hundreds on a mini-computer with an OS, I'd rather just write this signal to a file that I can open up on a computer. I'm familiar w/ a lot of programming languages and should be able to handle the programming, if the documentation explains how to use the peripherals. Any idea what hardware I'd need to build this? Is there a way, for example, to use Stamp to capture these signals and store it on compact flash or thumb drive or something (in the FAT file format)? Thanks for any help you can provide.

Reply to
Kevin
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There are plenty of prefabricated solutions for what you want to do. For example in acquiring motion paths, I've used an accelerometer connected to this device:

This will do exactly what you want and write the logged data to a FAT- formatted card; just add power supply and an SD/MMC card. There is a bit of annoyance in that they don't use a sane/recognized CR/LF convention to write the logged data, so you'll have to process it with sed or similar if you use the text mode logging option and want to import it into a spreadsheet, but basically little massaging is required.

Reply to
larwe

I appreciate the quick reply. That device is absolutely brilliant! Thanks!

Kevin

Reply to
Kevin

Enjoy. The description on their page really doesn't do it justice - it implies that you need to play with firmware to use it as an analog data logger. In fact, updated firmware is already preloaded.

Reply to
larwe

Thanks -- actually - if it's as good as you say, I don't even think the manual would do it justice. There are two things I'm still not certain about it.

1) What is the sampling input voltage and how many divisions are there? I mean I don't know if it's 16-bit, 8-bit or anything in between, and I also don't know the voltage range that's being divided. Is it from 0 to whatever you power it with? 2) How long does it run? I saw that had a nice little battery pack, and I remember reading somewhere that it lasts 20 hours. 4 AA's and that's it? It dies that quick? Could you confirm?

thanks, kevin

Reply to
Kevin

It's built around a Philips (NXP) LPC2000-series chip, and I think most of those chips have 10-bit ADCs (1024 divisions) and use a voltage reference supplied on an external pin, nominally 3.3V. It looks like the Logomatic connects the reference voltage pin to the general 3.3V supply rail supplied by the on-board voltage regulator.

Sparkfun has a fairly active set of web forums; you might be able to get in-depth answers there...

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   Wim Lewis , Seattle, WA, USA. PGP keyID 27F772C1
Reply to
Wim Lewis

LPC2100 draws 80mA active and couples mA standby. It you need more than a few days of battery, you should draw less than 100uA standby. AVR or STM32 might be better.

Reply to
linnix

Sounds perfect -- I'll do so -- thanks for help.

Reply to
Kevin

Grrr -- that's more than I had hoped. =( Thanks for input though -- I'll look into those systems.

Reply to
Kevin

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