New alternative to the ScanGauge

After living with the current state of-the-art in Prius add-on instrumentation (The ScanGauge II), I eventually became frustrated with it. What really bothered me about the ScanGauge is the slow update frequency, and the lack of any type of analog display (meter type or bar-graph). So I decided to take on a project of building my own.

Here's what my current attempt looks like so far:


It uses a very bright LED backlit LCD with more resolution than the ScanGauge and is easier to see in all light levels, even with sunglasses on. It automatically detects when you turn the lights on and dims the display for night use (as shown).

The picture shows as I normally have it configured. The bottom line is showing a definable analog gauge in the form of traction battery amps. It has a resolution of 100 pixels and when set to amps it scales to a +/- 100 amps. It shows Charge (regen) amps by "growing" from the left side and discharge (driving) amps (as shown) by starting on the left side. It's surprisingly simple to read at a glance and since the screen updates at around 10 times per second, it's nice and fluid and enables you to really get useful information fast. The same amp figure is also shown in digital form just above (3rd line) and center. This way you can have a fast reading analog bar-graph as well as a precise digital readout all at the same time. Other than engine temperature and mode on the top line, The other items shown in this example are mainly information about my PHEV, such as mode, spoofed SOC, Amp-Hours, real SOC, Pack voltage, amps, and temp.

The updates are so fast that the camera actually caught the amps changing from 1.0 to 1.1 in the same frame! Many of the faster passive parameters are actually averaged and slowed down somewhat so the display isn't a twitchy blurry mess.

Each of the 4 lines of the display can show many parameters, up to 3 per line as a digital readout or 1 per line as Analog, similar to how the amps are shown. I can also split the line with an analog bar-graph on one side and the digital value on the other, but I didn't like it as much.

It also includes an audio annunciator that can make many different kinds of alarms and alerts. I have it programmed to make a short but quite audible beep on EV mode change, as my 2008 only beeps (3 beeps) if EV mode is canceled. It makes a high pitched beep on successful EV mode enable, and a low pitch when deactivated. It also makes other sounds to alert me to particular mode changes that are specific to my PHEV.

It can read and reset ALL Prius DTC's, not just the few the ScanGauge is limited to. I'm still evolving the user interface, but as of now it meets all my needs, including display and adjustment of custom modes and parameters from my PHEV. I recently ordered a higher resolution graphic LCD display which I hope to implement sometime soon which will give me a much nicer looking display with more area for Analog gauges.

I also read most of my Data passively from the CAN bus, so there is no lag and no interference with anything else that may be on the bus. When the car shuts down the system automatically goes to sleep. It will automatically power back up when the car is turned back on or (in my case) when I plug the car in and the custom BMS wakes up. This way I can monitor my charge; battery SOC, Amp-hours, Temp, Voltage, Amps, etc.

I've received a lot of interest in this so far, so I'm considering offering it as a kit initially, and then maybe later as a fully developed product. Right now it only works with a Gen II, simply because that's what I have. If I can find someone nearby with a Gen III that wants to work with me on development, I hope to have it working on it as well at some point.

I'd like to solicit comments and ask everyone's ideas for features they'd like to see included. This will be a Prius-specific device, not a generic one like the others on the market, though it's possible a future upgrade could add more functionality.

I plan on including a PC interface so it can easily be upgraded and configured, and customization will be much easier this way rather than spending hours entering hexadecimal with 3 buttons. My main user interface is a rotary encoder (knob) with built-in push button, so it's easy and fast to scroll through different modes and options. I've also recently obtained a higher-resolution graphic LCD display that will enable even more detail and more analog-style gauges. But even in it's current incarnation it's still way more useful than anything else I've had.

I realize there is a lot of activity in this area, and lot of prior art. Norm's Canview was the ultimate, but it's costly and complicated. I simply don't need that much information at once, and if I add an Extra LCD that big, I'm probably just going to lose it along with a window some night. There are also a lot of people working on smartphone versions, but I don't like this route either, as it requires setting up my phone everytime I get in the car, and then I have an even harder time using it for Phone/Nav/Music. It's already annoying to share one small screen for those 3 functions, so I didn't want to add yet another!

The hardware cost is likely under $50 even in low quantities, But I haven't priced everything yet. (I already had all the components laying around)

I have it installed over my rear-view mirror. It's easy for me to see and reach there, yet not in the way, and it's hard for others to see when I park my car in a questionable location. I ran a twisted pair cable from the CAN Bus connection at the Power-steering ECU up to the mirror, and it uses the same style (RJ-45) connector as the ScanGauge did, so it's backward compatible. It just slides in, so I can unplug it in seconds and take it out, leaving only a short RJ45 tail.

Questions? Suggestions? Comments? Ideas?

 

I'm using a CAN equipped microcontroller made by Silicon Labs. The part number I'm using is C8051F502. The whole thing only has a handful of parts.

The programming is indeed flexible. I've got it set up with "screens" that are pre-defined that can be selected with one knob. You can also have it trigger different screens depending on trigger parameters (such is in EV mode, in Park, etc.)

I hope to develop a PC application that lets you easily define your screens and add custom functions.

After using this, I can't ever go back to a slow cumbersome ScanGauge!

 

Yes, because I follow the official Bosch CAN spec, I can handle anything that comes down the bus. I haven't investigated any of the passive frames in the Gen III yet. My only concern is because of the integration of the HV ECU and the ECM that we will see less of the interesting/useful passive frames because there is no longer a need. It's also possible though that the Gen III is capable of high-speed active querying though.

Anyone have a Gen III and some way to log the CAN bus?

 

I have no idea yet. I'm not greedy, so I will charge just a small amount on top of whatever it ends up costing me.

This post is more an introduction and to help guide development. I need to get the project farther along before I can actually offer anything. And of course if we are going to tackle adding Gen III functionality, I need to get my hands on one.

 

Unfortunately this is the case, as key parts, such as the Microcontroller are only available this way. If I offer it as a kit, I will send the boards with all SMD's pre-soldered, and likely all soldering will be done. Basically it will just need to be installed in a case or mounted in some way, and connected. I call it a "kit" simply because it's not a finished product with a nice injection-molded housing, manual, box, etc. Consider yourself a Beta tester, and if there is enough interest proven by "kit" sales, then I can do the work to get it manufactured as a finished product.

Keep in mind some parameters such as Amp-hours are computed by my custom BMS, so are not normally available on the Prius, though it's possible to make a pretty accurate counter in software.

All these parameters are available, though not all as passives. All that means is the refresh rate would be slower, but for things like the temperatures, a 1hz update is still plenty! On one of my screens I have a high-speed engine RPM with bar-graph display, and also ICE Demand (what the HV ECU wants from the ICE). Interesting to watch!

FYI: There are only 3 traction battery temp sensors on the NHW-20, and one for intake air temp. Right now I'm reading the highest temp seen (max), but of course if you wanted to see all 4, you could.

Basically I can see any parameter you can see in TechStream and then some, though some are only available as active parameters with a slower update rate. I can also perform any test functions that TechStream can over the CAN bus.

 

On the current incarnation I try to gather as much data as I can passively, as it's much faster. But even when this is not possible, it still uses the exact same method the Dealer scantool (TechStream) uses to gather data. It is in no way harmful, and in fact the vehicle does not record or store query activity. There is no way this could void a warranty, but there is a slight possibility that any device plugged into the DLC3 (OBD) port could interfere with the CAN bus and cause a vehicle malfunction. It would be only in the event of a rare but possible electrical failure which could create a short on the CAN bus. If this were to somehow happen, simply unplugging it would restore the vehicle to normal.

 

Thanks for the offer Wick1ert, but I'm fortunate to live in the most Prius-dense place on the Planet (the SF Bay area), so I'm sure I'll eventually find one!

You'll be first on my list when I have something ready though!