00:00 |
- So far we've had a lot of discussion on how the PMU will supply power to connected devices but there is the other side of the coin to consider as well which is how we command the PMU to turn those connected devices on and off as required.
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00:12 |
In a conventional automotive electric setup, we usually divide the turning on of the vehicle's electronic systems into 2 stages called main and enable.
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00:21 |
The main power is turned on first, powering up electronic control systems of the vehicle such as the ECU, dash and any loggers but doesn't send powers to the injectors or ignition coils.
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00:32 |
The enable stage is turned on next and this is where we power up the actuators that the engine actually needs to run.
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00:40 |
The power supply is staged like this to allow us to turn on the main power to download logs, look at data on the dash, adjust settings in the ECU or even crank the engine without it being able to start.
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00:50 |
This is useful for building oil pressure, setting base timing, checking compression or any task such as.
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00:56 |
When a system like this is implemented with fuses and relays, the items that receive power at each stage are hard wired into the harness construction itself.
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01:04 |
The relay coil wires will be directly connected to physical switches, meaning that the only purpose that switch can ever have is to control that particular relay and its connected components.
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01:16 |
That being said, we still need to have switches and buttons in our system to control things.
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01:20 |
The beauty of using a PMU is that the input signals from these switches and buttons are decoupled from the direct activations of its outputs.
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01:28 |
Meaning that if we need to make changes to the system later on, we can accomplish this in software without having to rewire anything.
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01:35 |
This means we're going to need a control pad of some form and the majority of PMU manufacturers have tried to make this as easy for us as possible.
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01:43 |
There are a couple of common series of keypads on the market, being the 3KG1 series by Grayhill and the PowerKey Pro series by Blink Marine, that PMU manufacturers have chosen to support.
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01:56 |
Both of these keypads communicate to the PMU via CAN on the J1939 or CAN open protocols.
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02:02 |
We won't delve into the specifics of CAN communication in this course but if you'd like to know more about CAN communications, we do have another course dedicated to that topic.
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02:10 |
These keypads were initially developed for heavy industrial and marine markets, meaning they have excellent ingress protection ratings and are very robust.
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02:18 |
This also makes them perfect for our race car purposes.
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02:21 |
You'll need to confirm with your PMU manufacturer that the keypad you would like to use is compatible but most of the PMU manufacturers also directly sell one of these keypad series.
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02:31 |
Meaning they'll have communication profiles already configured in their software.
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02:35 |
While it'll usually be possible to get another brand of keypad working with a particular PMU provided the PMU's CAN configuration software provides enough flexibility, I'd recommend purchasing a PMU and a keypad as a pair from the same company as being able to make use of the pre defined communication profiles will save you lots of time and headaches down the line.
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02:56 |
Let's have a look at an example of setting up one of these keypads now and show some of the excellent features that you can take advantage of.
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03:01 |
The example we'll go through will once again be controlling our wiper motor but in this instance we're going to use our CAN bus enabled keypad for this.
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03:10 |
Now this is sold by Ecumaster along with their PMU16 so there are really excellent linking CAN profiles in the software that makes this keypad really easy to use and get the most out of but this is just a Blink Marine PowerKey Pro series keypad.
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03:28 |
Now a couple of features with these keypads that I really like are on the back we've got nice simple mounting, we've got a membrane for sealing and the whole thing itself is actually sealed as well.
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03:41 |
So really good ingress protection ratings.
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03:44 |
Each of these button positions can obviously be read individually and you can get translucent key caps that fit into these positions that indicate what that key will actually do and every one of these is individually back lightable to a different colour as well.
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04:00 |
So not only do you get a keypad, you actually get a bank of indication lights that say maybe whether that function is currently enabled.
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04:08 |
We'll go through setting that up and we'll show those different colours in practice.
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04:12 |
So the wiring for these keypads is really simple, on the back here we've got 6 wires, there's power ground, CAN high, CAN low and then there's actually two here that come with heat shrink on them, they're for an RS485 protocol hookup which is not something you're likely to be using in the automotive world so I wouldn't be worrying about those.
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04:32 |
But we get all this functionality from this keypad with only our 4 wires, power ground, CAN high and CAN low.
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04:40 |
So I've got that wired in, we'll just pop this down and turn our power supply on again.
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04:46 |
Make sure our PMU is switched on, we've got our indication light and once again over to our software, just double checking we are connected so everything's good to go.
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04:56 |
So the software is actually already set up for our wiper operation from a previous example that we've shown.
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05:03 |
What I'm going to do is show how to integrate the CAN keypad into our profile here and then change our wiper setup so a press of the button will turn the wiper speed on low, another press of the button will change that to high speed and pressing the button again will actually turn the wiper motor off.
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05:19 |
So I can come in here and I can set up a CAN bus keypad and I'm going to call this we'll actually just leave it with the default name of KB1.
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05:30 |
You can have multiple keypads in a vehicle, often it's really common to see one on the centre stack just to the left hand side of the driver but also down in the centre console area, there might be a different one with different features as well.
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05:45 |
The driver might not need to reach when he's actually in race mode.
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05:48 |
We've got a 4x2 7 colour keypad here, so we can change to that setting.
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05:53 |
Our CAN bus that it is wired into is CAN 2 and the CAN open nodes and the CAN ID are still going to be absolutely the default ones because this is still as it was delivered out of the box.
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06:07 |
So I can leave those as default and I can click on one of these buttons, any of these buttons and we can set that up.
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06:14 |
So I'm going to click on this button here, I'm going to change its name from K button 1 to K wiper control and it is going to be a latching switch, its first state will be 0 but its last state will be 2.
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06:30 |
So what that means is as we press that button, it will cycle through the states so if it's 0, it will switch to 1, if it's 1 it will switch to 2 and if it's 2 it will switch back to 0 and it will latch those modes as we give it a single press on that keypad.
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06:44 |
Now for state 0 colour we've got none which would be correct because that would correspond to being off so we wouldn't want a light.
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06:51 |
For our state 1 colour we've got green, our state 2 colour we've got orange, I'm just going to change that to blue because in my sort of thinking, orange and red are warning indicators whereas in state 2 we'd be running the wiper motor in high speed and that would be a standard state not a warning state so I wouldn't want orange there.
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07:10 |
So I'm going to select that as OK, select that as OK, now there's 1 more thing I need to do here to get this system up and running.
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07:18 |
There's actually 2 more things I need to do to get this system up and running.
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07:21 |
The first of which being I need to come across to my configuration and I need to enable the CAN 2 termination resistor.
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07:28 |
Now that comes back to how a CAN bus system is wired.
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07:33 |
You need a termination resistor at either end of the network bus.
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07:37 |
Currently our Ecumaster USB to CAN interface has one and now our Ecumaster PMU has one as well so we've got those termination resistors at either end of the bus which should get the network operating as we need.
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07:52 |
Currently our keypad here is actually wired to, its +12 volt line is wired to an output on the Ecumaster so I'm going to have to turn that output on to actually give our keypad power.
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08:08 |
So I've got that wired into output 11, so in our software here I can generate a power output, we won't call that output C, we'll call this output keypad.
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08:21 |
And it is a single pin, we're not running any parallel outputs here and it's output 11.
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08:27 |
Now currently that's got an in rush current setting of 120 amps.
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08:32 |
That's going to be fairly excessive for our little keypad here.
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08:35 |
In fact I would say our CAN bus keypad here is going to have absolutely negligible in rush current so I'm going to set that just off the bat to 2 amps and our maximum current I'm going to set to be 1 amp.
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08:49 |
Keypads like this are purely electronic devices, they've going to draw very small amounts of current, 1 amp wiring to it can absolutely handle long term so that's not going to cause us any issues.
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09:01 |
I'm going to give it a default power state of just on or off.
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09:05 |
What that is going to do is it's going to mean if the PMU is powered up, so we're providing power to that 12 volt switched pin on it and it's got its power connection to its main stud, it will turn that output on which is probably what we'd want in this situation because we'd be using a keypad for main control of the vehicle so when we turn that battery isolator on and we power up the PMU, we're going to have immediate access to our keypad as well.
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09:29 |
So if I click OK we should be able to see, yep our keypad is doing a wee startup sequence of flashing there, that lets us know it's now been provided with power.
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09:40 |
So back to our keypad setup, just double checking that setup, there's our latching switch.
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09:47 |
That should be excellent, so if I press this top button here now, yep we can latch that into state 1 which we set as a colour of green, we can latch that as state 2 which we set as a colour of blue and then it'll latch back to being off.
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10:02 |
So to get that controlling our wiper motor like we want here I can go into our wipers module, not our table there, go into our wipers module, and change our input channel, instead of being our wiper speed table, we can change that to be our CAN wiper control keypad button.
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10:25 |
And because our latching states are going to have the same numbers, we shouldn't have to change anything here, we can select OK, just get a hold of our wiper motor and we should be able to go to slow speed.
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10:38 |
High speed.
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10:40 |
And then turn it off.
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10:42 |
Excellent, and our motor did actually overrun a little bit there as well, I think we've still got our brake settings disabled.
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10:51 |
So we're going to change that back.
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10:57 |
So we should have our low speed.
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11:01 |
High speed.
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11:03 |
We can turn that off.
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11:05 |
And you'll notice that if we're in the high speed and we turn the wiper motor off it actually defaults back to the low speed before getting to that park switch and then braking those motor terminals.
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11:16 |
The reason for that is moving back to that low speed, there's just less current running through the motor so there's less energy in the system so it's not as harsh on the electronics in the PMU to provide that motor braking functionality.
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11:28 |
So while this example only shows a single button input, it's easy to extrapolate this out further to the rest of the elements in the vehicle that you want to control and you can see how powerful and flexible a PMU with a CAN bus keypad can be.
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11:42 |
In this module we've looked at using a control panel to send commands to our PMU.
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11:47 |
This is usually done via CAN communication with the 2 most common keypads on the market being the Grayhill 3KG1 series and the Blink Marine PowerKey Pro series.
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11:57 |
Both these keypads have changeable button labels, adjustable back lighting and various indicator lights as well.
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12:04 |
It's highly likely that other CAN enabled control panels will appear on the market and it will be best that you check with your PMU manufacturer to ensure the model you want to use is fully supported.
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