Monday, 24 December 2012
Thursday, 20 December 2012
Wednesday, 19 December 2012
Sunday, 16 December 2012
Sunday, 9 December 2012
UPDATE - Got the AT328 programmed and running the TV Out demo sketch sucessfully.
I'm writing this post on a Scroll Essential 7" tablet running Android 4.0 and a neat little case/keyboard to speed up the typing. Total cost, under 100 GBP.
Saturday, 1 December 2012
During the summer, Pringles crisps were giving away free speakers that clip on the top of an empty Pringles tin. The only drawback was that for a stereo pair I'd have needed to eat my way through 6 boxes of Pringles, and I'm more of a Tayto guy myself. Anyway, we went to see 'Skyfall' last month and my 13-year-old darling daughter got me to buy her 2 of the small cartons of Pringles for the film (costing about as much as 6 big tins in Asda!). I hung onto the empty boxes and discovered that a pair of speakers I had reclaimed from some old thing were a perfect fit for the Pringles tins. I soldered lengths of twin speaker cable to them and glued them onto the top of the tins with epoxy. To round them off I found some 'funky foam' in my son's craft box (I owe him a sheet now) and covered them with it. They sound amazingly good considering what they are and they look pretty contemporary too.
So I was good to go and the mini CD player I was going to use them with died. Typical.
If you've never heard of Tayto, well basically Tayto Cheese and Onion are the best crisps ever made.
Friday, 30 November 2012
The stove is now surrounded by a really outstanding hearth, with all the pipework boxed in using fireproof board and tiled with gloss black designer tiles. This has been 4 years in the making, but we are finally there.
From a technical angle, the stove and oil boiler are now properly valved (after 3 attempts!) so that they don't interfere with each other. We had the oil boiler repaired in October and new baffles, jet and pump were fitted to hopefully give it another few years service life.
Interestingly, priming the radiators for 5 minutes with the oil before turning the stove pump on seems a good strategy. I'm very keen now to incorporate this into the controller unit I'm designing.
Off to a Raspberry Jam later!
Sunday, 25 November 2012
Tuesday, 6 November 2012
The old inverter is integral to the power board, but the circuits are all the same so I can disarm the old inverter and run 12v, GND, Adjust and Enable connections to the new inverter.
Sunday, 4 November 2012
I got this meter on eBay for a fiver. I just took a notion for an old school classic meter because it reminded me of my grandfather who was a radio amateur from the 1920s and built his own radio kit. In his house in Cushendun there was this amazing shortwave transmitter he'd built. It was in a hammered finish metal case about 5 feet high and had proper dials and meters on it, like something from a 50s science fiction film. I've always loved that retro stuff.
Anyway my meter reads 0-5mA and with a 1kOhm resistor in series it reads the 5 volt PWM output from the Arduino perfectly. I have a notion to use it as a thermometer readout although it would look equally great in a car.
Saturday, 13 October 2012
My son and I have been using this to watch old episodes of the bonkers-but-brilliant 1989 TV game show 'Interceptor' on YouTube. If you have never heard of 'Interceptor' then you are in for a treat. Think 'Treasure Hunt' meets 'Crystal Maze' (it was made by the same production company) with a maniac in a black leather trench coat chasing you around the English countryside in a helicopter while jolly-hockey-sticks Annabel Croft gives you directions to the loot. Unfortunately there were only 8 episodes made before it was cancelled, but they are TV gold.
"Television, the drug of the nation,
Breeding ignorance and feeding radiation."
('Television' - The Disposable Heroes of Hiphoprisy, 1992)
Tuesday, 2 October 2012
All the details are helpfully on this guy's blog -
Now my motivation for looking into this was the desire to use one of the tablets as a front end for a vehicle diagnostics system.
- Cheap Android tablet computers don't have serial or Bluetooth capabilities;
- Without Bluetooth or serial how do you communicate;
- While these can be added, it is complex as the Android ROM has to be altered;
- They do have wi-fi as standard, but Android doesn't like ad-hoc networks, only access points;
So the RPi acts as a proper AP, not an ad-hoc network, complete with DHCP for managing IP addresses automatically and it can run an Apache server, PHP, MySQL and anything else you fancy.
Now I need to find out more about AJAX.
Tuesday, 11 September 2012
The computer was pretty hard to upgrade as it had to be completely taken apart and one internal tiny Phillips screw was very tight. In the end it needed to be removed by cutting a slot across it with a MiniCraft drill fitted with a circular cutting blade and then using a thin screwdriver to take it out.
This is the little solid-state drive removed from the computer. It is a real oddity, a parallel (not SATA) drive similar to the type of hard disk drive used in early versions of the iPod, which was a popular upgrade for the Acer a couple of years ago. Working versions of these iPod drives are hard to come by now, but luckily Acer later had versions of the A110 with SATA hard drives installed so the main printed circuit board has the solder pads for a SATA connector.
I should have taken a 'before' photo, but here is the 'after' one. The SATA connector was not fitted and had to be soldered in. I got the connector from China via eBay for about 40p! Soldering it was a pig of a job (sorry pigs), because my eyesight isn't what it used to be and this was surface mount type stuff. In the end a lot of trial-and-error and testing and the SATA socket was in place. One other pair of pads needed soldered to supply 5-volt power to the connector and away we went. The SATA drive is 80Gb and cost nothing because it was salvaged from a laptop that fell off the roof of a car and was totally trashed. It was only about 3 months old at the time so the drive is almost new.
I also added an extra 1Gb of RAM to the slot on the right to bring the total to a respectable 1.5Gb.
Then a bit of cutting was done inside the case to accommodate the larger drive and it was all re-assembled. I used my home-made USB DVD drive to load Ubuntu 12.04 on and this is now a really tasty little computer.
And here's Fin (7) doing some Scratch programming on a wet afternoon a couple of weeks ago at my ma-in-law's caravan!
Sunday, 19 August 2012
Thanks to the work of some guys on the RaspberryPi forum, Gambas3 is now running on the little computer. So after a couple of hours work installing a new OS image with Gambas3 on it and getting the hang of it I have managed to get the bar chart program running. As before the Psion II is pretending to be the data-logger and is sending out random data in the format I have currently settled on.
It works pretty well, but the RPi is being pushed close to its limits here and the mouse has a habit of becoming inactive. Ultimately I think I will need to learn Python and go down that route using the widget approach to get a GUI output, but there is a pretty steep learning curve there.
The next step is to finish off the touch monitor and get a module (driver) for the touch panel and the calibration program running on the RPi.
Tuesday, 14 August 2012
I bought a couple of these little USB 2.0 hubs for £1 each in PoundWorld intending to adapt them to be powered hubs for use with RaspberryPi computers. Alan here (http://pihub.blogspot.co.uk/2012/06/raspberry-pi-power-supply-and-powered.html) beat me to it, but I wanted to give it a go with a flying power socket. As usual, heat-shrink sleeve comes in to save the day.
I didn't like the original USB lead and plug so I bought a USB-to-Micro USB cable (again for £1) and cut it in half. One end goes to power the RPi and the other is the input USB.
The input USB has only 3 connections made, the red power wire is cut short and ignored. I did connect the ground (GND) wire though because the purist in me doesn't like the idea of floating grounds (blame my MSc). The output for power to the RPi via the micro USB plug only has the GND and +5v connections made and the other 2 signal lines were chopped short and ignored.
The power input was made from a DC power socket salvaged from an old lead for a dead PDA and with some black heat-shrink it looks quite professional and hard-wearing. I have a small hoard of 5v 2A power supplies that were for various long-deceased gear and one of these is powering all this.
And it works like a dream!
Friday, 3 August 2012
I was working on my Silvercrest/LG TV recorder this evening, which has developed a fault with the DVD recorder part. The hard drive end works fine, which means it is worth trying to repair. The odd thing is that I cleaned out the DVD drive, cleaned the lens on the laser and blew some air round everything and hay presto it started playing a DVD again out in the workshop. 15 minutes later I took it back into the living room and hey un-presto it has gone kaputt again. This is typical. Maybe the house just has bad karma.
I will investigate further.
DVD Drive model - MEZ36295702
Tuesday, 31 July 2012
Okay, I now have a working Gambas program that will read a formatted RS232 data stream and display the data as a dynamic bar chart. To test this I rigged up my trusty old Psion II LZ and wrote a little OPL (Psion programming language) script to output a suitable random data stream. The project is running on a laptop at the minute because I haven't gotten Gambas onto the RasberryPi yet and apparently it is quite slow, but I love the graphics.
The system is designed to work with 8 sensors and the data is 10-bit (values between 0-1023), so the format of a data frame is (at the moment) 18 bytes as follows -
- 'A' as the start character, the program reads data and ignores it until it receives an A;
- Pairs of bytes representing the upper and lower 5 bits of the 8 10-bit data values;
- 'B' as a terminating character.
To avoid confusion and make debugging easier, the 5-bit data is sent as bytes in the decimal range 32-63. The ASCII codes for A and B are 65 and 66 respectively so no valid data byte can be an A or B or an ASCII control character. Once the whole thing is operating properly, I may changes these. The program detects all the possible errors in a data frame such as invalid data, invalid frame length or the terminator arriving too early and if any of these occur, the bad frame is ignored. The program also has a timeout so that if no valid frame is received in 5 seconds, the chart is reset to zero.
For testing purposes the baud rate is at 9,600, but this is because the Psion works best at this rate. Once the PIC is back in action, I will test the baud rate in steps right up to 115,200 checking for errors and see how we get on.
Monday, 23 July 2012
Monday, 2 July 2012
For the time being, we built a Lego box for the RaspberryPi, pretty much from scratch. The sticker on the top was to hint at the computer being destined (one day) to be the front end for a vehicle diagnostic system, but that's as far off as it ever was! It's a lot of fun trying to get there though.
Friday, 15 June 2012
An early analysis has shown that we have saved £750 this winter in reduced fuel costs by installing the new multi-burning stove. Taking into account that this was a mild winter, the whole install will break even in just over 3 years. The oil tank was filled a year ago and is still 1/4 full (so around 900l used) and we have used roughly a tonne of coal, giving a total fuel cost of around £750 for winter heating. This compares with around £1500 in the last winter when we were on oil only.
Phoenix Gas have been delivering a mail shot in our area (again) offering a piped natural gas service. When I 'phoned up (again) to order it they told me (again) that it isn't available in our area. Should they consider targeted marketing perhaps?
Tuesday, 27 March 2012
The interface circuit requires 4 lines of I/O, 2 digital outputs and 2 analogue inputs.
The touch screen was salvaged out of a cheap PDA which had stopped working and the graphical LCD (GLCD) is a standard KS0108 driven via a bespoke I2C 2-wire interface I bought on eBay although in future I would just interface one of these directly to the PIC.
Tuesday, 20 March 2012
UPDATE - Toyota have no more ISC valves of this type (worldwide) so I would be looking at around £350 for this little thing shipped from the US!
Monday, 19 March 2012
App Inventor (MIT) running under Windows XP
Sunday, 11 March 2012
After a while I went back to these monitors and stripped them out again.
This is the inner section of one of the Venturer 6.2" monitors, the part that swivels up and down, removed from the outer case. Only 4 connections are needed to drive this and they are marked on the reverse of the circuit board - V+; GND; Video; Video GND. You can also rig your own colour and brightness controls if needed because all the necessary connections are available, but they may not be needed as the monitor defaults to usable settings. It has no back to it, but as this one will be cased or in a dashboard that didn't worry me.
There is a photo here that shows the back of the monitor and the control signals (brightness, colour, wide etc) are the bigger connector to the left of the main power and video connector.
Monday, 9 January 2012
Sunday, 1 January 2012
With the motor running and one sensor connected to a multimeter set to measure frequency, I got a steady 6.3kHz and when a bit of resistance was applied (i.e. a finger and thumb) the speed reduced and the frequency with it.
Being able to send digital pixel data via I2C directly to the screen would be, well, brilliant.