1202 ALARM

I've been planning getting the Toyota MR2 back on the road and one of the things I have been messing with for the last 20 years is getting a decent sound system without breaking the bank. The MR2 originally had the front speakers in the dashboard with an optional subwoofer under one of the seats, but the dash just doesn't provide enough baffle for a decent sound. In 2010 I built this speaker cabinet which sits between the seats and provides pretty good sound along with 'flux capacitor' visual effects! I have since recovered 2 of these weird speakers from a high-end plasma television I stripped out. The sound quality is frankly amazing for the size of the units. The internal baffle and reflex design is excellent. I want to see if these could be either fitted inside the doors or mounted as pods on the doors themselves. To go with these I need a subwoofer which can either fit under or behind the driver's seat and this little one came my way. It was part of a Hitachi s...

This is just a quick post, really to link to the short video I made below showing my latest data-logging experiment, which takes in a number of technologies. At the core is an Arduino Nano doing the actual logging with code derived from work I did using PIC microcontrollers a few years ago. There are two parts to this - Reading up to 8 10-bit analogue values (range 0-1023); Reading the frequency of a PWM signal. These values are output serially 10 times per second (at 115200 bps) in what I call a data 'frame' which looks like - <AABBCCDDEEFFGGHH> Each frame has 18 bytes terminated by '<' and '>'. The pairs of letters represent a 10-bit value split into 2 5-bit nibbles and these values (0-31) have 64 added to them so that they are displayable ASCII characters to make debugging easier (range is decimal 64-95) Putting these together gives the basis for a data-logging and dashboard display system for my (currently ignored) 1988 Toyota MR2, but it needs a...

Being a 1980s car, the MR2 doesn't have a DIN radio slot or ISO connections for car audio. The surround had been butchered at one point years ago to try and make a CD player fit and looked grim. On top of that the lid for the ash tray had fallen off and as nobody is going to smoke in the car I took the ash tray and lighter out and stuck the lid down permanently with epoxy. So I needed a 12-volt socket to charge my 'phone and to neaten up the radio surround. I got this lightweight radio in Lidl on offer. It has no CD, but plays back from SD cards and USB devices, which suits me for a summer car. Power output is low, but I'm putting a power amp in my centre speaker cabinet along with a pair of better speakers, so not a problem. All 4 outputs can drive the MR2's own speakers. The red panel will be covered in black vinyl from a big old handbag I got for 50p in a charity shop and the 12-volt sockets are a £1 adaptor from Poundland. Only drawback at present is the USB h...

  Taking the throttle body off the MR2 is a pretty simple job with one exception.  There are 2 coolant hoses that go in and out of the Idle Speed Control Valve (ISCV) which are a pain in the backside to re-fit as there is so little space in the engine bay.  This is the real problem working on this car because everything is so tightly fitted in.  Anyway, after spending about 30 minutes fiddling with the hose clips I came up with the idea that I needed pliers with an extra wide nose to crimp the clips open so I could get them back up the hoses.  A bit of searching in my scrap boxes and I found these 2 threaded clips which I pushed onto the pliers.  DIY extra wide nosed pliers.  Job done in under 5 minutes with these!

Little video showing a 7-inch LCD monitor connected to an Arduino running the TV-Out library.  For this test I connected a Manifold Air Pressure (MAP) sensor directly to the Arduino using analgue pin 0 (AN0) to create a bonkers boost graph.  Sucking and blowing on the pipe makes the bar graph change.

 MR2 Black-and-White Image I got bored today and started mucking around with a start-up logo for the vehicle data system.  The Arduino TV-Out library has a neat 'Bitmap' function that will load a properly encoded 1-bit image into the image buffer.  I spent a bit of time on PhotoShop working on a photograph of an MR2 until I got reasonable 1-bit black-and-white picture.  This was converted to a C++ style array using Image2Code, a neat little application and with a bit of editing, this was included into the Arduino sketch (program). The result is pretty good for a 1-bit picture at 184 x 72 pixels and extremely Sinclair ZX81 retro.  The idea is to have this as a start logo and also for display when the system is in any idle mode.  It looks a lot sharper on a 6-inch or a 7-inch screen too. I also got the Tachometer routine working on the 18F4520 PIC microcontroller.  It counts the time between pulses arriving on the INT0 interrupt pin and the i...

I have nearly finished converting the battery in the MR2 from the piddly little 35Ah to a bigger 55Ah one. There were a few considerations with this. The battery terminals were too small, but I got the big ones in Halfords along with new earth cables. I also discovered that all the time I've owned the car the engine earth strap was disconnected which explained why the car was so hard to start! A trip to a scrap yard got a battery bottom clamp (off a Citroen) for a fiver and I made up my own rear clamp. The battery is clamped in securely and isn't going anywhere, but the big problem is the intercooler which is supported by the existing battery top plate (red thing below). If this wasn't the case I could lose the plate because it isn't really necessary, but then the intercooler would be flapping about a bit. As a stop gap I've bolted risers onto the plate because the new battery is 20mm lower than the old one and the top plate needs to be level, but I'm g...

  I finally got it working tonight. PIC --> Raspberry Pi --> Android App PIC is reading 8 analogue ports and outputting the data every 0.1s via serial over USB.  The Raspberry Pi is running an Apache server and in response to an HTTP request to a PHP script, it reads the serial data and re-formats it into a simple fast JSON array.  The Android tablet is running a custom app from App Inventor to make the HTTP request, get the JSON response and display the data. The next step is to get a nice bar graph interface working and set up the Manifold Air Pressure (MAP) sensor I have in the car so that the thing can be tested reading boost from the supercharger. Oh yeah and I have to get the Raspberry Pi working as an Access Point (AP) again.  I did this before okay, but with a different wi-fi dongle.  This is critical to using it in the car to send point-to-point data to the tablet.

Here we have a PIC 18F4620 in data logging mode collecting analogue values from 8 ports and outputting them serially via the USB bridge.  The software formats the 8 10-bit analogue values into a 'frame' like this - {HLHLHLHLHLHLHLHL}[CRLF] and these are sent every 1/10 of a second at a baud rate of 115,200.  The H is the top 5 bits (most significant) of the analogue value and the L is the bottom 5 bits (least significant).  To add clarity when testing, I added 40h (64) to these values to make them printable characters instead of control ones so the data frames can be viewed in the Putty terminal program. This is Putty running on the Raspberry Pi receiving the data frames from the PIC.  The text 'SERIAL READY' is sent after a reset and is also a useful test. What next?  Wait and see, but the clues are Apache, PHP5, Android and access point. Need a cup of coffe now.  And some heat, for May it is freezing here in Northern Ireland a...