Friday, 10 December 2010
Saturday, 4 September 2010
Saturday, 28 August 2010
I got some technical stuff about the iPaq online and have details of how to dismantle it safely and will see if the screen flicker is maybe just a loose connection.
Wednesday, 18 August 2010
I managed to solder one of the RS232 wires on after this, but not the other one, it is very fiddly. I'll have a go tonight or tomorrow again and report back what happens.
Tuesday, 17 August 2010
Another kind donation, this time of a nice O2 XDA 2 PDA/Smartphone (HTC Himalaya), running Windows Mobile 2003. The owner told me the 'phone wasn't working and the battery wouldn't charge, but it was quickly apparent that the fiddly little connector at the base of the 'phone wasn't right. The cradle had an option to charge a second battery in the cradle itself, so I took the battery out of the 'phone and charged it that way and the unit powered up perfectly and did its thing.
A quick search revealed the excellent XDA Developers website with a huge wiki and a forum and I quickly had an HTC service manual for the 'phone and the pin out for the connector. I was thinking of fashioning a serial cable in the same way I did for the iPaq using the power plug adaptor (the iPaq and XDA use the same plug, but different pin out), but the power adaptor was damaged as well making me think the 'phone had suffered an accident in the connector department (always painful).
I carefully dismantled the XDA last night and was amazed when the 22-pin connector fell out of the 'phone. It must have suffered a serious shock because all of the 22 little surface mount solder joints had failed which explained why it wasn't charging! Anyway there was no mission of re-connecting the socket and to be honest that wouldn't have helped, what I really need is a power connector and a 9-pin D male for RS232, directly connected to the XDA, a little ignorant looking maybe, but for a dashboard mini computer costing nothing perfectly acceptable.
The big problem now is whether I can solder half-a-dozen tiny wires onto even tinier PCB pads, something I doubt, but am willing to give it a shot. I may try and locate better connection points further back on the main board, but everything is absolutely minuscule on these things nowadays. Bring back the Russian radio sets of the 1970s with their hand-wired transistors and cardboard cases, much easier to repair!
Sunday, 15 August 2010
Tuesday, 10 August 2010
And here we have the first attempt, RPM and throttle position (TPS) on screen. Okay I'm cheating a bit because the data is coming from the bench test rig, but it's a step forward.
I've also had this displayed on the 7 inch LCD screen via the VGA-to-Video box, but at 640 x 480 resolution it is hard to read. I think experimenting with the colour scheme might help, but using composite video is unfortunately always going to be fuzzy. The physical rig looks good though and I'm thinking of spraying the LCD case matt black and incorporating the keypad into it.
And then adding some KITT displays and speech synthesiser.
Tuesday, 3 August 2010
Well thanks to some pointers from Boris I got a working bar graph (progress bar) on the Psion II and using machine code too. And I'm over 40. The Psion's RS232 capabilities are really put to the test in OPL though, the buffer fills quicker than the OPL can process it, so I trimmed the amount of data from 64 characters to just 18 without compromising on data. This allows the datalogger to send 8 channels at 10-bit resolution and the Psion to identify the channel to be displayed.
If I go any further with this I want to write more if not all of it in machine code especially to make sure the serial buffer is clear at the beginning of the program, which at the moment is causing problems.
The full set up on the bench. Eventually I want the Psion up in the cockpit of the car (okay, sitting on the dash) or as a hand-held garage diagnostic box and the PIC and so on will be permanently attached to the ECU in the car. Or something like that.
Wednesday, 14 July 2010
Having mastered RS232 on the PIC using JAL (which is just so good I had to order the book), this opened up another avenue, communicating serially with the Psion. So here we go, the Psion II is receiving the data stream from my 16F690 A/D device and selecting one of the 8 channels to display. I experimented with displaying a bar graph on the Psion LCD, but once again, the speed was against me. I fear I may need to look at some simple assembly to achieve that one.
Here's the full set-up with the Psion connected to the PIC via a (long) null modem cable, which would be spot on for connecting to my diagnostic system in the Toyota and taking readings up front in the driver's seat.
I'm keen now to try interfacing the Psion to the robotics SERIALLY, using a PIC 16F84/88 and a MAX232 to go from RS232 to general I/O, but with a bit of intelligence thrown in for good measure, things like command strings and so on.
Sunday, 11 July 2010
I discovered a handy procedure in the JAL libraries to display a progress bar or bar graph and although I could write my own it was quicker to just use this one. Voilá, a bar chart showing the analogue value, in this case a light level detected using a light-dependent resistor.
The LCD is only for testing and playing purposes, the real beef is the RS232 connection, shown here on an HP iPaq running Pocket Zeus Lite as a basic serial terminal.
The PIC is programmed to output the analogue value once a second (roughly) in a standardised 8-character format of
C1V0099# [C = channel; V = value (10-bit, range 0-1023); # = terminator]
which can be read by anything that can understand RS232.
So far only one channel is being implemented, but I'm going to remove the LCD now, re-program for 8 channels and start using the PIC timer and interrupts to get an exact 1 second interval between sending each set of 8 values.
Initially I'm going to use a Psion II for testing (seriously!) and later on build a bespoke dashboard module using a PIC 16F873, graphical display and steering column switches.
Thursday, 8 July 2010
I'll sort an RS232 interface tomorrow and then we are well on the way to some tasty vehicle diagnostics.
Sunday, 4 July 2010
My wife was at a school summer fete a few weeks ago and bought our son a fossil hunting kit for a pound. Basically it was a sandstone fossil encased in light plaster with a little hammer, chisel and goggles so you could have a go at 'excavating' your fossil. Anyway, my wee fella was really taken with this and has been showing everyone his fish fossil (on the left). I mentioned this to my colleagues, one of whom studied geology at university and tipped me off to a good place about 30 minutes drive away where Jurassic fossils are easy to find. I'd never heard of this before in spite of knowing the area pretty well. One problem is that it is along a stretch of busy and fairly dangerous road where most people wouldn't bother to stop.
So we set off this morning in the lashing rain, but by the time we got there it had completely dried up and we had a fun and interesting hour picking around in the rocks and came up with these fossils of ammonites and what appears to be a bone of some sort, maybe a fish tail. We probably missed lots more so we'll be back now we know what we are looking for.
Not exactly Sam Neill in 'Jurassic Park,' but not bad for a Sunday morning in Northern Ireland.
Thursday, 1 July 2010
The purpose of the knock sensor is to detect 'knock' in other words engine detonation and that allows the engine management to run the car with ignition advanced pretty much as far as it can go. If the sensor is faulty on the 4A-GZE engine, the 'Check' light comes on, you get error code 52 and the car goes into a safe mode with reduced performance so as not to damage the engine.
The original sensor was destroyed about 8 years ago by a careless mechanic who promptly went out of business before I could get it replaced. Just as well for him because a replacement ended up costing £150. I had tried several options to get around buying a new one including trying a wide-band one and one out of a Toyota Supra. The problem is that on cars of this vintage, the knock sensor was very narrow band and tuned closely to the knock frequency which is very specific to the engine and a function of stroke, bore, capacity, grandmother's birthday and so on. In other words using anything other than the correct sensor is not going to work. The galling part is that the actual active component is a tuned piezo transducer that you could buy for about £3, so the rest of the £150 is for a steel boss, a connector and Mr Toyota's works do.
The other thing is that the sensor is in a 27mm boss housing and has to be screwed into the block at the rear, a particularly hard to reach spot. Thankfully with the starter removed there is just enough room to get at it with a 27mm socket and that gave me a good opportunity to thoroughly clean the starter before putting it back in the car.
All seems well now with the new sensor, no error codes and the car seems more responsive as it should. The idle seems more stable now as well, which is a bonus although I still intend to change the coolant out to remove air bubbles which are a known cause of wobbly idling.
I also got around to fitting the shorter drivebelt for the alternator and now the air conditioning is pretty much disabled. If I can get it de-gassed soon I can take the compressor out to lighten the car and maybe as something I can sell for a few quid. This will also make fixing the oil pressure sender much easier when I get around to that because that means taking the alternator and bracket right out.
There's not a lot of room to work round the engine in one of these cars.
Tuesday, 22 June 2010
Sunday, 20 June 2010
My system will give some fuel boosting and go a bit further by providing a dashboard display of 8 of the most useful engine parameters as detailed below. I would like to use a PIC16F690 running at 20MHz to do this and connect the display via RS232, but I might go mad and use an entire computer at the dash end (P1 75MHz laptop motherboard) with a 6.5" video display as basically a terminal
1 - Throttle Position (5v)
2 – RPM (via LM2907 or similar f-to-v circuit)
The above inputs are used for the Booster circuit.
3 – AFM (5v)
4 - Boost (Add-on MAP sensor; 5v)
5 - O2 (Oxygen Sensor; 0 – 1v approx, needs 5:1 gain voltage amplifier)
O2 Sensor – Above 0.45v ‘Rich’ and below 0.45v ‘Lean’
[0.45v equates to stoichiometric air/fuel ratio of 14.7:1]
6 - ECT (Coolant Temp; 5v)
7 - IAT (Intake Air Temp; 5v)
8 - EGR (Exhaust Gas Temp; 5v)
Thermistor temperature (6-8) curve graph:
Cold Start Injector (‘Booster’) control
LED indicating Booster in operation
Value ‘live’ graphs for 8 channels
Fuel ‘Rich/Lean’ display (O2 above/below 0.45v)
Supercharger in play – actual not dash LED
Friday, 4 June 2010
It's only travelled 300 miles in the last six years...
It's got twin cams, 16 valves, fuel injection and a supercharger...
It's mid-engined and rear-wheel drive...
It's only got 2 seats...
It's got lowered suspension and adjustable shocks...
It has tricked-out engine management...
It can do 0-60 in 5.5 seconds...
They thought it was dead...
They were wrong.
Sunday, 23 May 2010
Wednesday, 12 May 2010
The blades are temporary and will be replaced by ones made from sections of 110mm soil pipe, although the angled brackets they will be mounted to are ideal for getting a pitch. I don't see the motor acting as much of a generator without being turned at high speed so I'm looking at using old bicycle parts to introduce some gearing (1:5 or 1:10, something like that).
The big problem so far is a lack of wind to see if it will turn. The kids' little windmill acts as a kind of wind speed indicator!
Tuesday, 4 May 2010
I hooked one up to the PIC voltmeter project which reads 0-5 volts as 0-1023 points and got a reading of 16 which equated to roughly 7 degrees. I'll need to spend more time on this because the room was clearly much warmer than that, but when I held the LM35 between my thumb and finger the reading rose steadily.
Sunday, 11 April 2010
This isn't the kitchen, but the utility room, which is an essential extension to our kitchen. About a year ago we were in IKEA and they were selling these worktops for £10 each in a sale, reduced from about £50. I should have bought 5 or 6, but stupidly just bought one. Cutting a long story short we added 3 wall units and one base unit with the uber-cheap plain, but hard-wearing Harlig doors. The handles came courtesy of another really decent person on Freecycle who was up-grading a kitchen and they have been incredibly useful.
I got to thinking that this represents about half of a 'standard' 8 unit kitchen and wasn't that hard to fit. The main reason is that the IKEA units are very well designed for DIY, tough, but quickly assembled (20 minutes per unit) and easy to adjust once on the wall or floor.
If anyone needs a kitchen fitted on a budget... :)
I got this door over a year ago on Freecycle and never got around to doing anything with it, partly through a lack of confidence in hanging doors and partly because I don't have a power plane. My brother-in-law got a really good Bosch plane and I borrowed that to fix our bedroom door which was sticking (I was also fitting a lock to it to give us some privacy when required!) and after getting that right I thought it would be nice to have the glass door into the kitchen instead of the cheap hollow one that was there. With a bit of trial and error and a lot of puffing and panting I got it done, not perfect, but not bad so I reckon I could do pretty much anything with doors now.
Monday, 29 March 2010
Saturday, 27 March 2010
Wednesday, 24 March 2010
Thursday, 18 March 2010
On the plus side I acquired a petrol generator that needs a little TLC after getting soaked in a winter flood. A bit of a strip down, a good clean and some WD40 and hopefully we'll get it back to life.
More of the buggy.
Monday, 8 March 2010
The hard drive is in fact a 16Mbyte Compact Flash card connected using a 99p converter bought on eBay. CF cards have an IDE-type interface so they are ideal as solid-state drives. The only drawback is the relatively low number of writes they can handle before they burn out. Fine in a camera, not so fine in a PC running an OS with a swap file. Ideal if using FreeDOS or Linux from a ramdrive though. In these cases you can even write-protect the CF card in some situations and it will have an almost limitless lifespan.
The VGA output could be taken via the VGA-Video converter to one of my little 7-inch displays (see earlier posts).
Sunday, 7 March 2010
I spent some of my weekend trying to sort out my wife's car, a 2003 Renault Scenic RX4 1.9dCi. The RX4 is an odd hybrid, a 4-wheel drive spacebus, which came along before any marketing guru thought up the concept of a 'crossover,' which seems to be a 2-wheel drive car masquerading as a 4x4.
Anyway the EGR valve was clogged up and un-clogging it has made starting the car a breeze, but there is a deeper problem causing power loss and white smoke above 2000 rpm. I've narrowed this down to a turbo or MAF sensor issue, hopefully the latter...
The experiments were pretty successful and on a hot day the water in the radiator rose to over 60 degrees Celsius without any insulation. That's the problem unfortunately. This collector is about 2sqm which is about a quarter of what would be needed and boxed up it would weigh too much to be mounted safely on a roof.
Anyway, this summer I'm going back to this idea, but I'm going to build a double collector using the other method from the CAE booklet, which is a copper pipe and vane design and will be less than half the weight.
Sunday, 28 February 2010
The buggy started life as a toy Lamborghini running on 2 6-volt motors, one driving each rear wheel. When we moved house I took the opportunity to ditch the upper body which had seen better days leaving a bucket chassis.
It has 2 6-volt emergency lighting lead-acid batteries wired in parallel to give a whopping 20 Ah. Most of these electric toys have batteries around 6-8 Ah. It doesn't go any faster, but this gives a much extended running time.
These are the new wheels on the buggy up close. I got these hand-truck pneumatic wheels on eBay for £15 and my colleague Johnny kindly helped me adapt them to fit on the buggy. I finally got time to drill holes in the axles for cotter pins to make sure the wheels won't fall off. It's unlikely this would happen because the washers behind them are a very tight fit, but better to be sure where children are concerned.
Friday, 26 February 2010
I got a little more work done on the Psion 2 interface board, but I'm getting some spurious results on the input port, so I'll concentrate on finishing the output port tomorrow by adding the 2 H-bridge ICs to drive the Lego motors.
Thursday, 25 February 2010
A kind donor gave me a broken car DVD player set with 2 nice 7 inch monitors. A bit of re-wiring and they now have simple 5-pin DIN plugs carrying power, video and audio. I then acquired an old VGA-to-Video adaptor that had lost its leads and power supply, but that was easy to sort out and here we have a test bar graph application running from an old laptop. The program was written in C using the OpenGL graphics libraries and runs under DOS.
I've re-created this in Linux, but DOS has a lot going for it in simple applications like this, most of all the fact it runs in RAM so is ideal if you're using a compact flash card as an alternative hard disk drive. Fewer writes to the card the better.
Wednesday, 24 February 2010
JAL is similar to Pascal in feel, but so easy to learn that any competent programmer should be able to master it in an evening.
Speaking of which, I may be getting back into web programming, which really stretches the mind if (as I did) you do everything from first principals.
Many thanks to Nathan for donating some servos for me to play with, here are the first results...
This is a simple start to driving servos from a PIC using the venerable 16F84. On power up, the PIC resets the servo to the mid position and then waits for one of two input pins to go low. One makes the servo swing to the right and the other to the left. The total range of movement is sub-divided into 100 steps so accuracy is good.
I'd like to use this in a scanning security camera application with some sort of simple motion sensing using maybe ultrasonics.
This device uses a KS0108 graphical display driven by a nice I2C interface to display the voltages read by a 16F873 PIC on 4 of its A/D pins. The display is just a horizontal bar with a label for the engine parameter being measured - boost (forced induction engine), oxygen (lambda sensor), engine speed and fuelling level.
The strange item on the right is the steering column stereo control from a scrapped Renault Laguna. This is wired as a 3 x 3 matrix with only 7 switches implemented. Two of these switches, [Vol +] and [Vol -], are used here to cycle up and down through the 4 engine parameters being measured so the driver can change this from the steering column.