LCD Smartie controlling analog gauges

ian · Post by **ian** » February 10th, 2008, 10:08 am

Hi everybody,

This forum helped me get LCD Smartie working with my custom hardware. Thanks everybody!

If you want to see LCD Smartie driving old analog gauges (or build your own setup), check out my project here:

http://www.diylife.com/2008/02/02/show- ... og-gauges/

Thanks again for the great software and support!

Cheers,

ian

Post by **mattcro** » February 10th, 2008, 6:49 pm

Looks pretty cool - a big analog gauge for CPU/mem usage is somehow much more interesting than numbers ticking on a display, although a CPU usage histogram/graph is cool too. You could use up about 4 drive bays with those gauges in a retro case mod...

From the video, it looks like you have the gauge update rate at around 250-300ms, and the gauges jump in noticeable steps (tho I just noticed the refresh rate is 150ms in the config screenshot). The gauges would probably look a lot smoother (ie analog!) with a refresh rate of 100ms or so, at the expense of a tiny bit more CPU usage. I guess the gauge controller can easily handle the extra data.

ian · Post by **ian** » February 10th, 2008, 6:57 pm

Thanks for the suggestion, I'll give it a try.

Another issue is that the gauge controller has 8 bit resolution (255 steps of resolution, ie 0-255), but CPU and memory usage are output as numbers from 0-100. More than half the possible resolution is lost in the scaling. I think this makes it 'tick' a bit. A big capacitor might help as well.

Cheers,

Ian

Post by **limbo** » February 11th, 2008, 5:04 pm

Very good project
The video is very descriptive

now its a sticky one

Post by **mattcro** » February 11th, 2008, 9:25 pm

Well, this project intrigued me enough that I had to have a stab at something similar

Thanks for the writeup and video Ian!

I've got an ATtiny2313 microcontroller hooked up to the PC serial port which takes in similar commands and produces PWM output to drive a meter in a similar fashion to Ian's setup. Mine's just lashed up on breadboard at the moment and hooked up to a huge old scrap meter (scale plate is about 12x6cm). It basically works! The tiny2313 has 4 hardware PWMs so there's scope for expansion.

The meter has a 500uA FSD 230ohm coil, and a 1000uF cap seems to provide a reasonable amount of smoothing - it's not bad without it (100ms update rate) but looks better with smooth movement.

I might build the circuit onto an FTDI type USB>RS232 dongle and power it from USB. The meter(s) could go in a suitably vintage box if I can find something.

Next retro-display idea: use a magic eye tube to show CPU load...

ian · Post by **ian** » February 11th, 2008, 9:39 pm

...or nixies, but I think thats been done....

Post by **mattcro** » February 22nd, 2008, 4:13 pm

I finally got around to doing a proper meter scale for my big old meter mentioned in my previous post... and here's what it looks like:

Some quick measurements of the existing scale plate, a bit of CAD, and it printed out beautifully. Now I just need to find a space on the desk for it...

ian · Post by **ian** » February 22nd, 2008, 4:20 pm

Very nice! Well done.

_X7JAY7X_ · Post by **_X7JAY7X_** » March 2nd, 2008, 7:22 am

Looks good. I started hacking one of those spinning LED caller id's, but I never finished it. There are many different variations but something like this http://www.amazon.com/Sharper-Image-Scr ... 83-5371308

grantb3 · Post by **grantb3** » March 2nd, 2008, 4:24 pm

mattcro wrote:I finally got around to doing a proper meter scale for my big old meter mentioned in my previous post... and here's what it looks like:

Looks fantastic. Are you going to put it in a case? Does it move quite a bit? We going to need some video!!