MoTeC M1 Software Tutorial: Ref/Sync
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Ref/Sync
13.42
| 00:00 | The next worksheet we will look at is the ‘Ref/Sync’ worksheet which defines the inputs to the ECU that give it information about engine speed and engine position. |
| 00:11 | These are some of the most critical inputs that the M1 receives as all calculations are based off these parameters. |
| 00:18 | For those of you who are familiar with MoTeC’s older hundred series ECUs, there are a few important differences here that we will discuss. |
| 00:28 | The two inputs we will be dealing with are ‘Engine Speed’ which was previously known as REF and ‘Engine Synchronisation’ which was previously known as SYNC. |
| 00:38 | We will go through the process of setting them up now. |
| 00:42 | The first parameter we need to deal with is ‘Engine Speed Reference mode’ which tells the ECU what trigger information to expect, and how to decode the information. |
| 00:54 | If we click on the drop down menu, a list of all the available trigger modes will be shown. |
| 01:00 | You can select the mode relevant to your particular engine. |
| 01:04 | You will notice that the worksheet displays some context specific help as well to give you a more detailed description of each parameter as we move through the worksheet. |
| 01:16 | Next we have the ‘Engine Speed Reference Tooth Count’. |
| 01:20 | This is only used in some modes such as multi tooth or missing tooth modes, and describes the number of teeth on the engine speed reference input. |
| 01:30 | If you are using a missing tooth trigger such as a 36-2 or a 60-2, this number should be set to the number of teeth including the missing teeth. |
| 01:42 | For example a 36-2 trigger disc has 36 evenly spaced teeth with two cut off. |
| 01:49 | This gives a physical tooth count of 34, but we would enter 36 which is how many evenly spaced teeth there should be. |
| 01:59 | ‘Engine Speed Reference Offset’ tells the ECU where in the engine cycle TDC for cylinder one occurs. |
| 02:07 | This is a critical element in calibrating the ECU so that it knows where in the engine cycle the engine is, and which cylinder is firing at any particular time. |
| 02:18 | This parameter replaces the ‘Crank Index Position’ or CRIP setting used in previous MoTeC ECUs. |
| 02:27 | The ‘Engine Speed Reference Offset’ angle will depend on the actual mode being used. |
| 02:33 | For multi tooth modes, the reference tooth immediately prior to the synchronisation tooth is known as the cycle lock position. |
| 02:42 | The offset is the crankshaft angle between this tooth and TDC for cylinder number one. |
| 02:50 | In a missing tooth mode, the cycle lock position is defined as the reference tooth immediately after the missing teeth and prior to the synchronisation tooth. |
| 03:00 | Here the offset is the crankshaft angle between this tooth and TDC for cylinder number one. |
| 03:08 | The way the ECU synchronises has been fundamentally changed in the M1 ECU. |
| 03:14 | In the older hundred series ECUs, the synchronisation process required the ECU to see the sync signal before it could determine engine position. |
| 03:25 | It would then wait for the next reference signal before the engine could fire and start. |
| 03:30 | With the M1, much of the required information is contained in the reference signal so the ECU basically pre-synchronises. |
| 03:39 | This means that as the engine can cycle lock as soon as it sees the synchronisation input and this leads to faster starting. |
| 03:49 | The next three parameters are ‘Blank Ratio’, ‘Wide Pitch Ratio’ and ‘Narrow Pitch Ratio’ which let the ECU decide when it should expect to see a valid trigger input and help reject unwanted noise. |
| 04:04 | These parameters shouldn’t need to be adjusted for the majority of engines and you can leave them at their default settings. |
| 04:13 | ‘Engine Speed Reference Minimum’ is used by the ECU to define a stalled engine state. |
| 04:19 | This needs to be set below the minimum reasonable cranking speed and again the default value of 50 RPM shouldn’t need to be adjusted. |
| 04:29 | Now we have the ‘Engine Speed Reference Test Speed’ and ‘Test Output’ parameters. |
| 04:36 | These can be used to simulate the engine running at a particular test speed and then the output to be tested can be selected from the drop down menu. |
| 04:45 | We will look at this in a little more detail later in this section of the course. |
| 04:51 | If we move down further we now have the ‘Engine Speed Reference Resource’ which defines where the engine speed reference input is wired to. |
| 05:00 | This may differ between packages and you can see that there is no drop down menu to allow us to change the input resource here. |
| 05:08 | In the GPA package we are using as an example, it is preconfigured to Universal Digital Input 1 and can’t be changed. |
| 05:16 | We have the same setting available for the ‘Engine Synchronisation Position Resource’ and this time you can see that we can configure this on an alternative resource if desired. |
| 05:27 | ‘Engine Speed Pin Pullup’ control allows us to turn the internal five volt pullup resistor for the Engine Reference input on or off. |
| 05:36 | This setting defines if the reference sensor is a Hall or a Magnetic input. |
| 05:41 | Magnetic inputs are also often referred to as reluctor or variable reluctance inputs. |
| 05:48 | In the case of a Hall sensor, the pullup control would be switched on, and with a reluctor sensor it would be switched off. |
| 05:56 | We have the same parameter available further down the menu for the Synchronisation pin as well. |
| 06:03 | The ‘Engine Speed Pin Pullup’ control is effectively the same as the ‘Hall or Mag’ setting from the older hundred series ECUs. |
| 06:13 | The ‘Active Edge’ parameter defines which edge the ECU will trigger off and this is going to depend on the particular trigger input and trigger mode. |
| 06:23 | This is critical with a reluctor sensor as choosing the wrong edge can result in timing drift as the RPM changes. |
| 06:31 | You can decide on the correct edge by using an oscilloscope capture of the waveform, or alternatively for many popular engines MoTeC will be able to provide a data sheet detailing the correct configuration. |
| 06:45 | MoTeC are also working on integrating an ‘Input Capture’ function which should be available very shortly. |
| 06:53 | This will provide a built in scope feature for analysing any of the universal digital inputs. |
| 06:59 | This will simplify configuration of the ‘Ref/Sync’ inputs without the need for an oscilloscope. |
| 07:06 | ‘Engine Speed Pin Threshold’ tells the ECU what voltage the reference input will switch at. |
| 07:13 | Typically for a reluctor sensor this would be zero volts, although if you have an input with an offset waveform, the ’Threshold’ value can be set to account for this. |
| 07:24 | If you are using a Hall sensor, this threshold should be set halfway between the low and high state voltages. |
| 07:31 | A value of around two to two point five volts will work well with most Hall sensors. |
| 07:38 | You can always come back and fine tune these settings later once the engine is running and you can use the live voltage values. |
| 07:46 | Another new parameter in the M1 ECU is the ‘Engine Speed Pin Hysteresis’ parameter. |
| 07:53 | This is very similar to the ‘Mag Levels’ table that was available in the older MoTeC ECUs. |
| 08:00 | In some ECUs this is also known as ‘Arming threshold’. |
| 08:04 | This hysteresis table provides the ECU with some warning that it is about to receive a trigger signal and that it should be ready. |
| 08:12 | The Hysteresis parameter helps the ECU to ignore any background noise on the trigger inputs as it will not start looking for a valid signal until the trigger voltage has exceeded the hysteresis value. |
| 08:25 | Let’s look at an example of a reluctor input. |
| 08:28 | as the voltage drops from zero volts, the ECU will ignore it until it exceeds the hysteresis value. |
| 08:35 | At this point the ECU is armed and waiting for a trigger event. |
| 08:40 | When the voltage rises back through zero volts, this is the point where the ECU will trigger. |
| 08:46 | With a reluctor pickup, the amplitude of the input signal will increase with engine speed, so a 2D table of Hysteresis voltage versus engine speed is provided. |
| 08:57 | With a Hall sensor, the waveform is a simple square wave that doesn’t change so the Hysteresis can be fixed at a single value. |
| 09:05 | Typically with a reluctor sensor, the Hysteresis value should be set at about a third of the peak voltage amplitude, ‘Debounce’ is another way that the M1 can reject unwanted noise and prevent this noise from causing any interference. |
| 09:22 | The debounce table is a 2D table of debounce time in microseconds relative to engine RPM. |
| 09:30 | How this works is that if the length the input signal is shorter than the debounce time, the signal will be ignored. |
| 09:38 | The way to correctly adjust the debounce table is by using an oscilloscope or the ‘Input Capture’ feature to measure the trigger signal length, but for most trigger inputs, the default values should be a reasonable starting point and need little to no adjustment. |
| 09:57 | You will notice that these settings we have just discussed for the ‘Engine Speed Reference’ input are also available for the ‘Engine Synchronisation Position’ input as well. |
| 10:06 | These will also need to be configured to suit the particular sync input on your engine. |
| 10:12 | Now we can move on to the main ‘Engine Speed Limit Maximum’ parameter, which is the main engine rev limiter. |
| 10:20 | This works in conjunction with the engine rev limiters page and we will go into more detail about this in the next module. |
| 10:27 | This setting is pretty self explanatory though and you can see that we have two settings for the main rev limiter - A and B. |
| 10:34 | These can be used in conjunction with a driver switch to change the rev limit in real time. |
| 10:40 | It is a good idea during this initial setup to make sure the rev limiter is set to a sensible value. |
| 10:47 | Below the ‘Engine Speed Limit Maximum’ setting, we have a couple of settings related to the engine speed warning. |
| 10:53 | These settings are optional and can be used if the engine speed warning mode has been enabled, to control the engine speed limit if a minimum or maximum parameter is exceeded. |
| 11:04 | We will look in detail at these warnings and others a little later. |
| 11:09 | This covers the critical steps to setup the Ref and Sync inputs but once we have entered all the relevant parameters, we can also use this worksheet to help confirm the ECU is receiving the correct signals from the trigger inputs. |
| 11:24 | The time graph on the right hand side of the worksheet will show you all the relevant information and diagnostic data from the ref and sync inputs. |
| 11:32 | This can be helpful initially to indicate that the ECU is receiving information from the trigger inputs. |
| 11:40 | At the bottom of the worksheet we also have the ‘Engine Speed Reference State’, status indicator. |
| 11:46 | This will tell us if the ECU is receiving valid trigger signals from both the ref and sync inputs. |
| 11:53 | When the engine isn’t running we will see this status indicate that the engine is stalled which means the RPM is below the engine speed reference minimum. |
| 12:02 | If we crank or start the engine though you will see the state change to green and show the term ‘Cycle Lock’. |
| 12:09 | This means that the ECU is receiving a valid trigger pattern that it can decode and it knows what the engine speed is and where in the engine cycle it is. |
| 12:19 | Pressing F1 while focussed on the ‘Engine Speed Reference State’ will give you a list of the possible states along with a description of what they mean if you do need to diagnose any triggering problems here. |
| 12:33 | Lastly we can also use this worksheet to calibrate the Reference Offset or CRIP to ensure the ignition event is occurring at the correct time. |
| 12:42 | This can be done by selecting ‘Check Timing’ mode from the ‘Ignition Timing Mode’ drop down menu. |
| 12:49 | The ECU will now output a fixed ignition timing equal to the value in the ‘Ignition Timing Check’ parameter. |
| 12:56 | We can set this parameter to a value that is easy to see on the crankshaft pulley or timing marks and then confirm the actual timing with a timing light. |
| 13:06 | If the timing we see with the timing light doesn’t match the the ‘Ignition Timing Check’ value, we can adjust the ‘Engine Speed Reference Offset’ parameter until it’s correct. |
| 13:15 | Once this task is complete, it’s important to remember to change the timing mode back to ‘Normal’. |
| 13:22 | I can’t stress enough how important this step is. |
| 13:25 | It is so easy to forget to put the ECU back into normal timing mode after this step has been completed and it can result in a lot of wasted time and frustration trying to diagnose why the engine doesn’t appear to respond properly to changes in ignition timing. |
