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misc/Saab_Trionic_8_Combustion Detection Module_on_Mazda_Miata_running_rusEfi/Saab_Trionic_8_Combustion Detection Module_on_Mazda_Miata_running_rusEfi.md

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+## Reverse Engineering Saab Trionic 8 Combustion Detection Module (CDM) output signals using rusEfi ECU
+
+###### by Andrey Belomutskiy, 2018
+
+* Table of contents
+  * [Overview](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#overview)
+  * [Hardware](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#hardware)
+  * [Detonation test scenario](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#detonation-test-scenario)
+  * [Detonation signals](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#detonation-signals)
+* [Next Steps](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#next-steps)  
+* [External links](https://github.com/rusefi/rusefi_documentation/tree/master/misc/Saab_Trionic_8_Combustion%20Detection%20Module_on_Mazda_Miata_running_rusEfi#external-links)
+
+
+This data would not be gathered without help from kb1gtt, stefanst, andreika, nighthunter, hankthefourth and many others.
+
+#### In this report we show how detonation on 2003 Mazda Miata MX-5 could be detected by means of ion sensing using Saab 55352173 Combustion Detection Module (CDM) and H6T60271 Individual Ignition Coils.
+
+# TL;DR
+knock and combustion detection outputs of 55352173 are digital. Knock is reported with a series of 50us pulses, more pulses
+meaning more detonation. Combustion signal seems to be just a comparator giving logical true if ion sensing wire voltage is below certain level. First wide pulse on the combustion output seems to be flame front phase while second wide output
+seems to be showing post-flame pressure, with the middle of this pulse correlating with moment of peak cylinder pressure.
+
+Knocking - note a lot of blue line pulses (1ms timebase)
+![knock](tldr_knocking.png)
+
+Knocking (50us timebase)
+![knock](knock_signal.png)
+
+Not knocking or knocking way less - note lack of blue line low level pulses (5ms timebase)
+![no knock](tldr_not_knocking.png)
+
+Combustion signal seem to be just a comparator
+![combustion](combustion_signal.png)
+
+[All the videos mentioned here](https://www.youtube.com/watch?v=1y1dXTg9iMg&list=PLwj_BUeepTNB6eddVd7_KtyqiFYOJ75jy)
+
+# Overview
+
+While Saab Trionic systems were using ion sense forever, only the latest eighth generation
+uses individual ignition coils and external CDM. Prior to T8, a highly integrated ignition cassette was used which would
+make repurposing it for DIY applications harder.
+Trionic 8 system does not have camshaft position sensor or knock sensor with combustion detection module running on ion sensing
+signal from ignition coil producing both phase and detonation detection.  
+
+More recently, Mazda and BMW seem to be using ion sensing approach again.
+
+### Hardware
+
+Here are all the Saab components we will be using (only two coils pictured while four coils would be used)
+
+![parts](saab_2005_parts.jpg)
+
+Ferrari 124792 spark plug extension is used to connect original Mazda Miata spark plugs with bullet terminals removed with Saab COPs
+
+![hardware details](hardware_details.jpg)
+[youtube: Hardware Details](https://youtu.be/rUZ_-_hRnDU)
+
+![frankenso](frankenso_assembled.jpg)
+
+![hardware overview](engine_bay.jpg)
+[youtube: Hardware Overview](https://www.youtube.com/watch?v=1y1dXTg9iMg)
+
+Knock detection wire has 0.8KOhm pull-up to 5v, combustion detection signal has 5KOhm pull-up to 5v.
+
+### Detonation test scenario
+
+2003 Mazda Miata 1.8 VVT Automatic running on rusEfi open source ECU.
+
+Engine coolant temperature 100C, ambient temperature 4C, violent 40 degrees advance from 1500 RPM to 3500 RPM timing table.
+
+Detonation is audible in 2000-4000 range with 50% throttle pulls from parked.
+
+Detonation is also audible while parked, revving with brakes applied in "D" gear selector.
+
+![timing](knock_ignition_table.png)
+
+[youtube: It's knocking!](https://youtu.be/FQ9ii0eXjmA)
+
+#### Detonation signals
+[youtube: Four signals we see on the oscilloscope](https://youtu.be/7aafaZgr2AE)
+
+[youtube: No detonation while driving - baseline](https://youtu.be/2fNrJ7NDFm8)
+
+[youtube: Knocking while driving](https://youtu.be/eehx5zH8igI)
+
+[youtune: Knocking while driving zoomed in](https://youtu.be/QXTaa1mGbwE)
+
+[youtune: Knocking while standing on brakes 40 degrees timing](https://youtu.be/ylvMqOD50bY)
+
+[youtube: No knocking while standing on brakes 25 degrees timing](https://youtu.be/jS3LXw_v9ls)
+
+And that's it! We have seen enough to get some code for the rusEfi firmware to start consuming this knock singal data!
+
+### Next Steps
+
+1) Produce same outputs without CDM module
+
+2) Try Mazda H6T61171 ignition coils - these are a bit longer and narrower, seem to fit my Miata engine.
+
+3) analyze [raw waveforms](2018_01_05_miata_rigol.zip) and detect knock based on just ion sense signal without CDM
+
+![Coils](H6T60271_and_H6T61171.jpg)
+
+Inside of 55352173 Saab Ionization Detection Module
+
+![Inside](Ionization_Detection_Module_55352173.png)
+
+### External Links
+
+[rusEfi Patreon](https://www.patreon.com/rusefi)
+
+[rusEfi ECU](https://www.rusefi.com/)
+
+[rusEfi forum](https://www.rusefi.com/forum/)
+
+[rusEfi store](https://www.tindie.com/stores/russian/)
+
+[Trionic 8](https://en.wikipedia.org/wiki/Trionic_8)
+
+[Saab 9-3 wikipedia](https://en.wikipedia.org/wiki/Saab_9-3#Second_generation_(2003%E2%80%932014)) 
+
+[Spark Advance Modeling and Control](http://www.fs.isy.liu.se/Publications/PhD/99_PhD_580_LE.pdf)