Datalogging/telemetry with a wireless router

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Re: Datalogging/telemetry with a wireless router

Postby festy » Wed Jan 11, 2012 6:10 pm

If you don't want to wait, they're auctioning off a couple of prototype boards at the moment, but they're a little more expensive ;)
http://www.ebay.co.uk/sch/raspberry_pi/ ... ksid=p3686

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Re: Datalogging/telemetry with a wireless router

Postby VL400 » Wed Jan 11, 2012 6:14 pm

Yeah been following the development of it, looks good so far. Last I read there were some issues with part of the toolchain for the graphics side of it but otherwise should be a very handy little board.

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Re: Datalogging/telemetry with a wireless router

Postby festy » Sat Jan 21, 2012 11:28 am

I hooked it up to a running engine for the first time, I think I need to switch the LCD to 8 bit mode and look for other ways to speed up the screen refresh - it's a little slower than I'd like.
But at least it works ;)
http://www.youtube.com/watch?v=x9GyRrYKxSk

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Re: Datalogging/telemetry with a wireless router

Postby VL400 » Sat Jan 21, 2012 1:15 pm

Nice work :) I run my logger in 4 bit mode but with an AVR doing just the logger its prob faster than the router running an entire OS.

Some high resolution on the MAP :lol:

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Re: Datalogging/telemetry with a wireless router

Postby festy » Sat Jan 21, 2012 1:38 pm

The router runs at 250MHz and I've stripped out a lot of the 'normal' processes to keep it fast - and my LCD is connected via a USB serial uart @ 38400bps.
The picaxe on the other end of the serial line does background serial rx into a 1kb buffer. The 'foreground' routine just loops checking for a serial rx interrupt, and sends each byte from the buffer to the LCD - starting from the last buffer pos up to the current buffer ptr.
The lcd bytes sent from the router to the screen are a mix of data and cmds for positioning etc - the picaxe currently doesn't do anything more than serial->4 bit parallel conversion.

I'm logging at around 5Hz and part of each cycle includes updating the LCD - and at 38400 I should be able to transfer enough data to update the screen at 40Hz so might have to test the screen on a pc to see whether it's the picaxe/screen or the router that's too slow.
One of those r-pi boards would run 3x faster and I could have the LCD on the GPIOs and do away with the picaxe all together, so might not persist with this until I can get one.

And, my MAP sensor is a high precision model ;)
I've given I think 6 digits to each of the ADX objects that get diaplayed - the logger has no idea that MAP is going to the top right position, so doesn't do any rounding. Maybe I should apply the ADX's "Output Digits" value to the displayed values :oops:

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Re: Datalogging/telemetry with a wireless router

Postby festy » Sun Oct 28, 2012 7:41 pm

I've been re-visiting a few of my unfinished projects recently, so decided to fire up the Raspberry Pi that I got a while ago to see if it was any use as a logger.
It took me a few hours to write a Perl module to drive an LCD from the GPIO pins (I'm amazed no-one had written one yet) and then about 10 minutes to port my logger code to the R-Pi.
End result is 8Hz logging, and a better screen refresh rate so it looks pretty promising 8-)
There's enough spare GPIO lines to add a few buttons - and spare SPI, i2c and uart ports which I'll use to add a RTC, 3 axis accellerometer and some ADC inputs at some stage later on.

The only parts required for this version of the logger are:
Raspberry Pi board ($38)
20x4 LCD ($7)
2Gb or larger SD card ($5)
Jumper wires to connect screen to R-Pi board ($3)
Optional - USB thumb drive for storing logs (otherwise it stores them on the SD card, but a USB drive is more convenient)
USB car charger or other 5v supply capable of supplying at least 1 amp
and some sort of case would probably help too :roll:

It's not in the same league as VL400's logger, but it's a bit of fun and does what I need.
http://youtu.be/iYu8XQRJmYE - the screen flicker is because I was writing some debug messages to the screen between each update and forgot to turn it back off :oops:

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Re: Datalogging/telemetry with a wireless router

Postby festy » Sat May 11, 2013 9:36 pm

I was mucking around with my logger a while ago and wanted some analogue inputs for a 3 axis accelerometer.
I would have used SPI, but the one I had on hand was an ADXL335 analogue sensor so thought I'd use that.
Plus, I have a few more sensors I'd like to add to my car so extra inputs are always handy so I knocked together a USB 10 channel 10 bit ADC module.
I haven't got it properly integrated with the display yet but it's logging data well enough.
Here's a log of me giving it a bit of a shake - the red line is the Z axis, hence the 1g at rest compared to 0g for the X and Y axis:
3axis1.png
3axis1.png (19.07 KiB) Viewed 2177 times

I still need to calibrate the channels - the Y/blue axis is out by about 0.2g...

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Re: Datalogging/telemetry with a wireless router

Postby VL400 » Mon May 13, 2013 2:13 pm

Nice, very handy addition for dialing in a track car and being able to correlate the engine logs with what was happening to the car.

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Re: Datalogging/telemetry with a wireless router

Postby festy » Thu May 16, 2013 3:44 pm

Now with integrated HD video recording, and I've started experimenting with telemetry overlays this afternoon...

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Re: Datalogging/telemetry with a wireless router

Postby VX L67 Getrag » Thu May 16, 2013 7:44 pm

YOUR FAR TOO CLEVER!!!

Nice work!

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