This car uses Genboard v3.2 #204 that has seen use in a Volvo PV : MembersPage/MattiasSandgren/VolvoPV
It never worked quite ok, blew a few injector FETs and drivers.. long story. But Gustav tested it on his SAAB, ignition only, and it worked very well.
But now it was time to try injectors. That didn't turn out so good. As soon as the power is turned on, the injector outputs go active. For how much time ?
The PA0 - PA07 pins are all set high (5.0 VCC).
What seems ok:
- Injector FETs
- FET drivers
- what type ?
- if MC33151D (inverting), than pullup R154=2k7 recommended, because 10k might allow a few msec "priming pulse"
- if it was self-assembled with nonstandard noninverting fetdrivers, than strong pulldown could help
- Configuration (no injector outputs in use)
- Firmware (1.0.36 and 1.0.73 were tested)
Type of FETdriver is very important.
- We discovered the pull-down R153 was missing on this board
- which is the way it should be !!!!
- and we added (10K) => very bad idea
- R153 acts as a pull-down to ground for output pin OC0 which is kept low.
- and the pull-up R154 (also 10K) was removed.
- bad idea
In the schematic that is how it should be IF fetdriver is noninverting !!! Schematic allows either type, but assembly must consider the type used. We always used inverting
Before further investigation see if they installed nonstandard noninverting fetdrivers
We cleared EEPROM - factory restored, then did basic configuration. But as soon as power was applied the outputs were active. If the processor RESET line was set (active low) the outputs were active until we fixed the mixup with R153/R154.
We tried our own short and very basic code to test the injector outputs. We got the same behaviour as with the VEMS firmware from the outputs when we explicitly set the corresponding output to be an output (not input) and set it high. As we don't have the source code we can't tell what the other pins are set to.
We suspect a hardware issue, that we can't pin-point. At the same time the schematic reveals only OC0 and PA0-PA7 and these seem to behave like they should with our own code. So no other pins or components should pose a possible problem. Right?
What does the VEMS firmware do wrong that we do right? Still the firmware can't be blamed, it works on other boards, but the methods used seem to have the wrong effect on this board.
Early boards like this one used non-inverting FET drivers. Is this a case of the wrong boot loader used with the wrong firwmare?
What information does the bootloader contain? What is the correct bootloader version to use for this board? What does the firmware know or assume about the FET drivers state and function?
What to blame?
We're sorry we can't describe the problem better, we could produce a lot of measurements and tests but all we have seen looks alright.
This trigger wheel (2 teeth on iron/steel disc)is in use, works fine.
Here is the car, work in progress, just painted after all body and chassis work:
