Pug Pt2

Started down the Speeduino path. Ordered the Mega and board from Josh which arrived quickly and downloaded the git repo. Fired up the Arduino 1.65 IDE and the Speeduino code loaded and compiled without error.  Downloaded a copy of TunerStudio and after replacing the TxRx dll Рall good. TunerStudio found the board without problems.

Now need to order all the components to populate the board.

Getting all the bits from a single distributor is just about impossible – I’m trying to juggle availability and delivery costs for what is a small order. On top of this some suppliers have minimum order quantities but this can get ridiculous. I need a single 5.6V 2W zener but RS parts minimum is 50 items. They aren’t expensive individually (~20c) but what will I do with 49 spare diodes? I need a 22pin Molex connector but RS will only sell me 5 and the pins have a minimum order of 100 @ 14c so I have to buy $14 worth of pins….

There is also one or two parts that simply aren’t available locally so I’m stuck with $35 delivery for about $10 in parts. So it’s RS for whatever I can get locally and DigiKey for the rest.

In the meantime, I bought a Hantek 1008 8 channel USB (PC) oscilloscope on eBay. Each channel is about 1Mhz bandwidth which is plenty for a scooter. I gutted an old Pentium 4 motherboard and extracted the 20 pin Molex “receptacle”, used for the power, cleaned it up a bit and soldered back on the leads from the PC power supply. This makes a 20 pin extension cable with some exposed contacts for connecting the Hantek. I also need to strip out a single extra wire for Pin 22 (11 isn’t connected) – it comes from the Air temperature sensor cable and the ECU diagnostic comes on if isn’t connected. ¬†Hooking it all up I now get this


This is exactly what I wanted. Yellow is the Crank Position Sensor. Clearly a 23 + 1 tooth wheel. 15 degrees between teeth. Blue is the injector. Purple is spark. The engine is 4 stroke but the CPS is driven from the crank and there is no camshaft sensor. Therefore the engine uses a “lost spark” and “lost injection” i.e. both the spark and injection fire every revolution. Makes the whole EFI somewhat cheaper to build. It would appear that the “missing tooth” on the CPS is about 6 pulses @ 15 degrees / pulse so 90 degrees BTDC. I can’t simply pull the cover off as the CPS and the alternator are not isolated from engine oil and I don’t have access to a gasket set should it tear during removal.

Now need to wait patiently for the arrival of parts and start to get the Speeduino assembled.

Current plan is to get the “input” end of the Speeduino up ASAP. This will be TPS, CPS, Coolant and Air Temp sensors. There aren’t any hard to get semi conductors in the input path so it should be achievable. I’ll have to power the Mega via USB temporarily too.

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