Channels ▼

Al Williams

Dr. Dobb's Bloggers

Serial Storage

March 12, 2010

There's an old joke: What do you get someone who has everything? Somewhere to put it. For some reason, it seems like more often than not any embedded system I develop turns into a data logger even when I think it won't. But that means I need somewhere to store data.

In the "old days" this was easy. Most of my devices were "full blown" CPUs with address and data busses and they weren't connected to any external computers. So you'd wire some battery backed up RAM to the board and you were good to go.

These days, I mostly use single chip CPUs that don't have external busses per se. You can chew up I/O pins and interface anything, of course, but on a 28 pin CPU, you hate to build your own multiplexed memory bus. I've used serial EEPROMs, of course, but they have their own problems (mainly speed and write wear).

However, I noticed the other day that Microchip now has 64 and 256 KBit serial RAM chips. RAM isn't always the best choice for a standalone data logger (depends on the situation) but if your logger is connected then you really just need a fast place to store data until you pass it along and this looks like it fits the bill.

If you really want non volatile storage, I've used SD cards (which have the same problems as EEPROMs) or check out Ramtron's F-RAM devices. F-RAM offer fast writes, low power, and no write wearing by using a novel technology.

Related Reading

More Insights

Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.