Quick Update

Lately, it’s been pretty busy around the house so I haven’t done much beyond trying to wrap my head around Xojo and the source code for Comvette. I’ll elaborate more about what I’ve had to do to get things working but the short list is:

  • Spin up a virtual Linux machine to use. The software won’t compile nicely on the Windows version and I’m not programmer enough to adapt Wes’ scripts.
  • Set up the Pi to allow access. (This is actually Wes’ default. It took me a bit for discover that fact though.)
  • Set up Xojo on the dev box to talk to the Pi.
  • Adapt the scripts. (Mostly paths.)

Next I will modify the software look and feel to embrace the monochromatic instrument cluster on the late model C-4.

All for now! Be well.

Touchscreen Chassis

I finally got a couple of nice days in which I tore the center console, the trim piece on the dash, and radio /audio head unit out of the car. I measured everything and, sure enough, the unit is completely different is size from the early C-4. It’s also a bit challenging in that the four attachment points are offset differently from the front of the radio. One is set back 3/4″, one 1-3/4″, and the others in between. They are irregularly distributed around the face as well. This means that I will have to redesign Comvette.com model.

First and Second Sketches

The first step in the process was to gain access to the dash and measure the existing unit as well as the mounting points. In my C-4 model that meant pulling out the plastic shifter console, the center vent unit and the plastic radio trim piece for the center part of the dash. Once those were out, I found two bolts holding the head unit in place.

Once everything was clear, I measured and made a rough sketch.


With measurements in hand I fired up Progecad, an AutoCAD clone that is pretty affordable. I created a two-dimensional plan view, printed it, and took it out to the car to field check it.

Now armed with updates and additions on paper, I modified the drawing and then transferred the plan view to Autodesk Fusion 360 via a .dfx file. If you’re not familiar with it, Fusion 360 has a really reasonable license for makers i.e. it’s free. It’s also easy to use although there is a bit of a learning curve. I realize that sounds contradictory but the software requires a shift in thinking for me, and that’s a slow process. I’ve been gradually working it into my workflow, which is why I started in a more conventional CAD package.

3D Model

In Fusion, I moved the sketch into three dimensions, generated a model (for posting) and then generated a .stl file for my 3-d printer. The original Comvette chassis is designed to be cut from acrylic but I’ve chosen to go with a 3d printed one, at least for the prototypes because it’s “what I’ve got.” I have a CNC router in the works, so I might wind up cutting a final version, but there’s no real time-line and I want to keep the project moving. Additionally, while the original C-4 audio system looks like it mounted with four bolts, all on the same plane, this one features each one at a different depth, as the model shows.

I uploaded the new file to Slic3r and discovered that the object was too large for my build surface, So I had to cut it in two for the printer. Once that was accomplished and the design sliced, I started the printer.

Printing took about seven hours. I won’t have time to try it in the car until the end of the week, but it fits the screen well enough. If it fits into the dash, I think that I’ll reinforce across the top and bottom to alleviate any strain on the screen.

Fresh off the printer with the supports still attached.
Started removing the supports
Left-hand piece (upside down) mostly cleaned up.

The next step for the prototype is test fitting, after which I make modifications as necessary to the model and reprint. In the mean time there’s a lot of setup and configuration to do on the Raspberry Pi, as well as a radio and a power management system to build..

The C4Pi “Carputer” “Infotainment” system

I ‘ve started research on the RPi system for the ‘Vette. I’m accumulating some part too (see below). I’ve outlined the project into four parts:

  1. Research
  2. Adaptation of the Comvette Project to my 1993 C4
  3. Documentation
  4. Version 2, adding certain features either using Wes’ Comvette software or moving to a complete Linux, Android or Windows deployment in lieu of Comvette.
Project Breakdown
Version 1 Details

Part 1 — Ideal Capabilities

Wes Westhaver’s Comvette software has some pretty nice features and is an ongoing process but I think it’s worth the time to explore other options as well. I intend to do this concurrently with getting V1 up and running in the car. One reason for this is that the Comvette software duplicates features that I already delegate to my phone. So, while I wouldn’t mind offloading Waze from the phone to the new system, for example, but I do use the phone for calls. I use ALDLDroid to read and log the ODB1 systems via a Bluetooth box plugged in to the ALDL on the car. Neither of the latter features are available in Linux version. Additionally Wes Westhaver’s Comvette software supports his home brewed FM stereo radio receiver. He also provides a front end for the Raspian MP3 audio player and MP4 video player. He’s working to add support for

☐ OBD1 diagnostics display and data logging. (in progress)
☐ GPS flight recorder. (in progress)
☐ Sport seat recliner and bolster control.
☐ Dash-Cam recorder.
☐ Backup camera.

–comvette website

Operating System Options

I like the notion of a backup and dash cameras, especially given that there are USB models on Amazon.com for $25 or less. I’m not so interested in the “flight recorder” but as I noted, I wouldn’t mind passing the Waze tasks from my phone to the onboard systems. There is not a Waze version for Linux currently so that will require some more research. I would also like to figure out how to move the data-logging functions from my phone to the onboard systems. Again, there is not a verison of ALDLDroid for Linux, so more research is necessary in order in order to find something that will talk to the ALDL on the car via bluetooth.


Corvette Audio Woes

Speaking of audio system repairs (in my last post), I have to do something with the sound system in the Corvette as it’s slowly dying. The radio works, usually, but the CD player is dead. I don’t even have cassette tapes any more, although to play stuff from my phone, I use a cassette tape adapter. Don’t laugh too hard, it works. It doesn’t sound great, but it’s better than the FM radio adapter / transmitter.

I’ve been pondering what do do about the audio system for some time actually. This is actually a pretty standard C-4 dilemma. Do you repair and keep the car original or upgrade? Both have their own set of issues. I mean, let’s be real. It’s a C-4 Corvette.  It’s not going to become as much of a collector car as other models and even with the 40th Anniversary trim, it’s still a C-4.  Further, while repair is possible, it’s several hundred dollars at least, and perhaps as much as $700 for a rebuilt head unit. There are several other pieces as well that look equally expensive to repair as well. Plus, even if I service it, it’s still going to be a twenty-seven year old electronic device utilizing technology that even older.

The other option, replacement, is a bit less problematic once you get past the “keep it stock” thinking. But there are still two issues both grounded in Chevy’s decision to put a Bose audio system in the majority of the C-4s. The system sounded good in its day–actually mine still sounds good when it works! But it is not standard in terms of size or configuration. The head unit is neither single nor double DIN, and is often referred to as “1.5 DIN” in size. A sindle DIN system can be installed using after-market kits, but the ones that I’ve seen don’t look right. They’re out of place in the 1990s monochromatic cockpit of my ’93. Further the affordable (from my perspective) single DIN units lack features. Although there is one single DIN configuration that attracts me. It features a pop-up touch screen that looks interesting. But touch screen systems and gadgetry of any sort get very expensive very quickly! Further, I don’t particularly want to add a screen that will occlude the Driver’s Information Center and climate controls. That’s not a deal-breaker but certainly to be kept in mind.

I’ve read of people successfully installing a double-DIN system, but the modifications required to fit such a unit into the the dash put me off. We’re talking demolitions.

The second issue with replacement has to do with the nature of the Bose system. Rather than a head unit running to an amplifier, running to the speakers, each speaker in the C-4 Corvette has an independent amplifier on-board. While you can certainly rewire, and adapt the rear enclosures for standard 6×9 speakers, that adds time and expense to the project. I’ve looked at some installations that feature android tablets or similar installed but they also seem to require extensive modifications to the dash or to impede my view of the Driver’s Information Center.

But wait: remember the post before last (Raspberry Pi is a really useful platform) about the utility of card-based computers?  Well it turns out that fellow member of the Corvette Forum, Wes Westhaver has put together a touch screen “infotainment” system for his early model C4 that is controlled by an RPi. His site is comvette.com and he’s got a pretty detailed write-up of the project in the blog there.  It’s attractive in that it requires little or no cutting into the existing wiring harness. It ties into the speaker harness with standard hardware and everything run by the RPi is completely independent of the Vette. Wes’ software is licensed under the GPL too. He’s also put together from home-brew hardware including a Power Management System that shuts the computer down cleanly when the ignition is turned off, or a FM radio receiver. With the RPi, you can use USB peripherals such as a touch screen, a GPS receiver, or thumb drives. You can’t beat what he’s put together for less than $300 at any price. Further, some quick research reveals that the RPi has been used as a “carputer” in several different ways, so there are options even there.

There is a catch in that there are differences between the early and later C-4s and thus some of the information on Wes’ page may not apply to my car. In fact, that’s where I started this evening. I’ve been looking at the factory service manual in order to get an idea of how to tie the RPi into the ‘Vette audio system. I’ll have to do some adapting but I don’t see anything too challenging. Except building the the electronic pieces, that is. I haven’t built a radio since the mid-seventies and that’s part of this project.

The Car…

Is a 1993 Corvette coupe with the Fortieth Anniversary trim package and has a bit of a story. My dad was the second owner and when he could no longer get in and out of the car, in 2008 or so, he parked it in his barn. This was after he offered it to both my brother and me. When he passed away in 2011, we were faced with the decision of what to do with the car. Originally, we were going to get rid of it as it needed a lot of work. At that point it had been sitting in his pole barn for three or four years, by and large with a dead battery. Rodents had gotten at the interior and into the engine compartment. The tires had developed flat spots and looked like they might be dry-rotted as well. It was hard to tell the condition of the body as the dust was caked on pretty heavily. There was no way that I wanted to put it on the market in the current condition, even as a project car.

Our long-time family mechanic hauled the car back to his shop. He didn’t even want it inside the shop as we had no idea what would happen when he hooked up a battery charger. It turns out that nothing burned up, although the battery was shot. He then cleaned out the air box, put in a battery, and the thing started right up, much to everyone’s surprise! It also blew crap out of the tailpipe for quite a bit. Now Danny, the mechanic, knew a bit about the car, as he had maintained it for Dad. Once I asked, he shared with me that it was mechanically sound and had been maintained regularly. But he also warned me about the potential for hidden critter damage that might not appear for years.

With the car more or less drivable, I registered it and then had some folks take a stab at the interior. They got it livable, if not sellable. Then I dragged the car to MD to continue the cleanup process and put it on the market. I put new tires on it, had the fluids changed out, had a fan issue resolved. Over the course of the work, I discovered that I didn’t really want to get rid of it. I’m not sure what Dad would have advised, and I got some good input about keeping vs. selling. I know that we really didn’t need a third car nor the costs inherent.

But Corvette. Even more, Dad’s Corvette.

This has continued over the years. I probably should have sold it. I should keep it because one or the other of the the kids might like it. I even had it on the market for a bit last summer.

But then our eldest got her license. And then, with three adults in the household going in different directions on a daily basis, to five or more different jobs, the need for a third car became apparent. As it stands now, she’s driving the Caravan. SWMBO is driving the Journey, and I’m “stuck” with the ‘vette as a daily driver.