
mainboard:
- AVR
- max232
- basic sensors
- knock sensor filtering
- 1..4 channel EGT (precision low-drift amplifier)
- Variable Reluctance sensor (for toothwheel)
- 2 injector drivers
- stepper
- MAP not mounted
- SPI ?

Software compatible to v2.2 board

daughter:
- SPI ?
- secondary AVR (non-critical functions) 
- more sensors 
- 4 inj or ignition (select at assembly, no ION-sense)
- 4 ign with ION-sense analog output
- external ADC (for ION-sense. Might not be necessary)
- LSU4.2 WBO2 (or some kindof DDL?)

If the daughter AVR resets (or fails), the engine won't stop,
just run without WBO2 and ION-sense.
---------------------------
There are a few issues with that design, number one is that I would like to
keep the wb circuit away from any injector or ignition drivers. Some of the
voltages I work with are very small. The other is the ION part. I think that
it will need a box of it's own. I would also like to keep the switcher that
creates the high voltage for the ion sense far away from the rest of the
design. ION and WB will probably not work well in the same box. In any case
it is hard to fit two layers of boards with chassi cooled components. Plus,
I think that it is vital that we have a ton of high current drivers on the
main board.

My idea was something like this:
Mainboard:
AVR
MAX232, stereo plug for commo cable (An Autronic feature that is impossible
to live without.)
Basic sensor, including o2.
Crank and sync trigger inputs. (Standard MS input and hall input. External
signal conditioning for VR sensors.)
Eight high current drivers (ign, inj or general. 4 of them with PWM)
Several low current drivers.
(for relays, boost control, AC, fans, ignition and soo on. More is better.
SPI or I2C internal comm (for daugher board)
SPI or I2C external comm (for linked boxes)
MAP sensor
Stepper (if it fits without compromising the electrical design of the output
stages.)
* I would have placed it on the daughter board but steppers can cause
interference.


Daughter board:
AVR
external ADC.
EGTX4 on the external ADC, jumpers to connect them to the internal ADC
(requires four channels).
LCD output and enough button inerfaces for a handheld controller.
Knock sensor signal conditioning (I have VW knock circuit in eagle format,
50X60mm hole mount)
WB signal conditioning and control logic (requires at least four ADC
channels and two PWM channels).
Aux inputs.
SPI or I2C

If we fit basic protection components on the board it can be used standalone
as a logger or WB meter. An other point with this is that all the changes
will probably be made to the daugther board, I can't forsee any changes to
the mainboard if we follow this route.

Two mainboards could be linked this way:
* The primary board reads all sensors, reads triggers and control the
injectors. It then relays the signal conditioned trigg signals to the
secondary board. It also sends the commanded ignition angle and all sensor
data via SPI or I2C (primarily only the commanded timing is used). If a
knock sensor are fitted it retards all cylinders.

Any mapped cylinder to cylinder ignition variances are handled by the second
board, fitting a daughter board in the secondary box can provide cylinder to
cylinder variance.

It is of course possible to only use the trigg signals and the sensor
datastream and let the igniton board run in a semi standalone mode. Or one
can fit the sensor and trigger signal conditioning and run it in standalone
mode.

This leaves the design of the ion enhanced ignition open, it can be made to
replace the ignition board.

Do you have the eagle files MS-AVR the board and a cracked version of Eagle.
I can't load anything bigger then 80X100mm. I would like to start making a
proposition for the main board. I can't start with the daughterboard before
the mainboard are finished.

Jörgen

