Expansion Board for the underhood area
The intention is to make an external I/O board for Ver3 / Ver4 that hosts a number of high-end functions that does not fit on the other boards. It can also be used to collect all sensor information for the other modules and pass in on as a CAN data stream. The box must be built to withstand the environment in the engine compartment.
Dr Jekyll
- 2x CAN
- 8x EGT (Type K) - 8ch MUX to 1 ADC on ARM
- 2x Knock channels - 2 analog inputs to TPIC8101
- 2x WBo2 - 2 analog inputs to ARM
- MAP - 1 analog input to MCP3208
- MAT - 1 analog input to MCP3208
- CLT - 1 analog input to MCP3208
- TPS - 1 analog input to MCP3208
- 3x Spare - 3 analog inputs to MCP3208
- 3x Input capture On header to CAP1.x
- 1x Input capture On connector to CAP1.x
- 4 more I/O's may be possible (because of connector)
Mr Hyde
- 2 L293 Stepper driver IC's configured as 8 push pull outputs or as 1-2 stepper drivers.
- 4 high current open collector outputs.
- CRANK and CAM inputs (LM 1815
- Keyboard Input
- LCD output
Anything YOU like too see on it? Then add it here:
The Plan!
Combine Dr Jekyll and Mr Hyde on a single board for lots of features, but this would probally make this board too big for an easy fit underhood. So the Mr Hyde side of the board can be removed to make the board smaller
That will make:
- Dr Jekyll: 76.8x100mm
- Dr Jekyll & Mr Hyde: 161x100mm
- To fit inside an alubos case
What can it do?
Using:
- EGT inputs:
- If more then eight thermocouple inputs is needed you can use more then one engine board
- Measuring MAT and IAT using Type K sensor
- AIT is airtemp before compressor (in forced induction applications) while MAT is airtemp (after charge cooler and throttle plate) right before air enters the cylinders. AIT is used in combination with MAT to calculate adiabatic efficiency (for the compressor).
- Cylinder Head Temp using Type K sensor
- Sensors for cylinder head metal temperature, i.e. more important than coolant temp. -Patrick B
- Also useful for other low voltage outputs sensors like strain gauges or for +-12v inputs with small hardware modifications
- Input capture
- Measure rotation speed of compressor (eg. mercedes 2.3 compressor) or turbo speed
- RPM of gearbox input driveshaft for measuring slippage of clutch (compared to crank speed) and to to help engine RPM control for fast switching in combination with wheelspeed and gearswitch
- RPM of automatic gearbox
- RPM of Marcell's FAN, why and how he won't say
- Spare analog input(s)
- Fuel pressure sensor
- Oil pressure sensor
- Fuel Flow
- Fuel Flow indicates (by flow meter) how much fuel the engine is using and is therefore a more important factor in tuning. -Patrick B
- Extra TPS
- Digital WOT signal
Brainstorming area:
TODO: Decide wich MUX we connect to the OPA
- Which CAN transceiver to use with LPC2119, Designed for now with MCP2551
- 4 EGT channels thru an 2 x (4 => 1) MUX like MAX359 or MAX309 (cheaper) to an OPA (For 8 EGT channels twin MAX3xx or one ADG507A)
- For MUX info read page 7 of: http://www.analog.com/UploadedFiles/Application_Notes/34661261AN369.pdf
- Lotsof headers (for unused pins ?)
- some logic level FETs at the edge of the board, and a stepper driver (1x stepper should fit onboard Jekyll, otherwise both on Hyde)
- Mini-Fit, Jr. Connectors for cheap I/O connections
- Type K has it's own set of connectors already designed for
- combustion pressure sensors. I saw they become cheap ($150) as they are going to be used in future engines. They would remove the need of the ion sensing (although apparently more expensive than IonSense, so most likely best use is validating ionsense results). But I don't know the signal shape. - Alexei
Other Issues:
- DC-DC +-15V is for OPA to measure minus temperatures (other uses than EGT) Also needed for the MUX.
- Type K has a faster update time than PT100, NTC, PTC Useful when measuring flowing air
- In the range 0-60C we want to minimize measuring error below +-1C
- Cost: OPA LT1882 6-7Euro + 6-7Euro for MUX MAX359, ADG507AKRU TSSOP 28 - 100 or more at $8.32
- Temp compensation for cold junction point, an MCP3208 and an NTC
- analog TPS input is superior, and perfect for determining WOT
- no guesswork involved, positioning the TPS (and setting 3 constants in firmware) is way easier than positioning the WOT switch mechanically
- Actually, idle condition is far more important, as:
- WOT can be determined without any throttle signal: the MAP is a better indication of WOT (at low RPM, 40% throttle can be 95kPa, which is a WOT condition, although there is no universally accepted interpretation for WOT )
- you'll need TPS-derived WOT condition (preferrably analog TPS sensor) when controlling boost target according to TPS (raise boost as TPS goes from 80..100%; otherwise TPS would be very insensitive in that area; this is a nice thing making throttly=>power curve much nicer - drivability)
- Actually, a digital WOT signal can be connected to a free analog input; as MembersPage/Gabor uses on v3.x - he only needs it as he is unfortunate to only have (idle, as that is important) switch in the project geo-metro.
- one might want a second TPS sensor for redundancy, but better be 0..100% than on/off.
Dropped:
- AD597AR in favour for an LT1882 OPA (much better temp tolerance than LM324) AD597AR also requires an additional OPA to measure minus temperatures since AD on CPU dont like minus voltage
- MUX HI509A won't work with 3.3v digital signals (logic 1= at least 4v)
- board-temperature SMT160-30 (SO8L, appr. 6 Euro) 1 Pin PWM to CPU (in favor of LM50 or MCP3208 and NTC)
- 8 injector outputs
- 2 IGBT's for Ignition +6 low effect ignition outputs
The last 2 would make it a full EFI board:a standalone ECM that controlls 8x Injectors and directly 2x Ignition (indirectly 8x Ignition). This is dropped in wait for the plan of an I/O chip
Current Status:
- Dr Jekyll
- LPC2119 with CAN option
- 4ch Type K input and 4ch optional ( 1(2) MAX3xx to 1 OPA LT1882 ) 8ch EGT for all you V8 lovers.. ;)
- DC-DC converter for V+ and V-
- 2x WB02
- 2 channel Knock sensor interface TPIC8101
- 1 MCP3208 for Mat, Clt, TPS, MAP, extra input (oil temp?) and for temp compensation of cold junction point
- Switched to SMD crystal and DPAK
- Mr Hyde
- Starting to take shape....
multiplexing low level signals
Add any results about this here.
Recived MAX359CWE, just waiting on LT1882 so some testing can be done.. [This application note uses a MUX to OPA for measuring temperatures thru type K]
Developers:
- MembersPage/JohanEriksson - The Idea and board development - Also the keeper of the schematics
- MembersPage/JörgenKarlsson - The Idea and electronics design