Hacking RF Instrument Cluster display

The Mazda MX-5 RF has a graphic LCD screen as part of the Instrument Cluster. I thought it would be cool to access it to show additional information on that screen. The LCD is 4.6″ with an FPC cable to the mainboard. The LCD is controlled by the graphic processor Yamaha YGV642, which would be the perfect option for customization. Unfortunately, Yamaha denied my request to share the datasheet and I could not find anything in the public domain. I decided to use an external graphics processor and implemented a video switch, to control the LCD. To accelerate development, I chose the Microchip development board and made a simple PCB with connectors and a video switch.

Of course, it is bulky, but I got immediate access to the LCD screen and can start work on software. The LCD screen has a resolution of 432×432 pixels with a simple RGB interface, 6 bits per color, with a 62 Hz frame rate. I was able to synchronize my processor with Yamaha, which allows me to insert a portion of my graphics and leave some untouched. My first test was the implementation of a digital counter.

The first project is the implementation of the digital speedometer. Current speed is available on the CAN bus, so it makes it easy to capture it using just one wire soldered to the mainboard, directly to the Rx output of the CAN receiver chip. Switching from “mph” and “km/h” is also available through CAN messages. I implemented this as well. The speedometer comes on screen after four clicks on the “Info” button, and the next click will turn it off.  During the road test, I found that the digits switched too quickly when the speed was on the borderline of the next number. To avoid this I implemented a simple filter, averaging 32 samples. Now it is perfect.

The next project will be an implementation of an analog clock, which will show up when the engine is turned off and stay until you open the door, or click the Info button to another feature.

The power reserve handle will show the battery’s voltage, which will be useful to see when the engine is off.

I will design a smaller single PCB with a microprocessor and FPC connectors, to make installation simple. CAN bus is not present on the FPC connector, so one wire needs to be directly soldered to the mainboard. The software can be updated at any time via USB cable.

Work in progress!

Opening and closing RF roof with a key fob

You can put the roof down while you approaching the car, how cool is this?

After successful implementation of the one-touch roof control module, next idea is to do this using a key fob from outside the car.

This is a very challenging task because the roof mechanism operates only when Ignition power is on. To solve this problem, I modified my ACC controller to control the IG relay instead. This module would listen to CAN messages and when activate IG relay when needed by pressing Lock or Unlock buttons on the key fob. After roof operation completed (which is also known as an event on the CAN bus) IG relay will be turned off. RF controller also can listen to CAN bus for key fob messages and activate mechanism when needed.

Quick implementation was successful, and I got everything working as desired. Because I already had Windows Controller installed, everything is fully functional. Technically windows controller could be optional, but if you leave windows down and then remotely put the roof up, there is no way to close windows without entering the car again. Also, in a US car after closing the roof, windows will leave a gap of 1″, which I can close remotely with one more click.

We tested it with RF 2017 and RF 2020, MT and AT versions.

This product will be available by end of June 2021 from our store.