Garmin HUD & ESP 32 stand-alone module.

A couple of years ago I upgraded my mobile phone, and was dismayed to find Garmin no longer supported my much-beloved HUD (Heads up display), rendering it redundant. It was only 7 years old at the time... is that acceptable product life expectancy? Gutted. 

I seem to remember reading somewhere that the same display was built into BWM cars ... are BMW owners in the same situation?

It featured in my Mini speedo video here. 

Thankfully, someone had reverse engineered the bluetooth serial protocol used to control the device. 

The original work was carried out by gabonator (here), Frank Huebenthal and subsequently by skyforcetw (here). Stunning work. Skyforcetw had even written an android app to interface Google maps to the Garmin HUD, excellent. Except nothing I could do would persuade it to run. 

So I tried skyforcetw's arduino library, and attempted to load it into an ESP32, and tried to modify it for SerialBT. After a lot of debugging and chopping of code from Frank Huebenthal's work, I finally started to get some meaningful information displayed on the HUD. 

So, after this success, a plan was hatched. I just want some meaningful info displayed. I'm not particularly interested (nor capable of) writing something for my phone to run , so I'm thinking about a simple speed display, and maybe some other info.. 

So a UBlox GPS module (this one's an M7, but it will work fine with the cheaper M6)  is hooked up to the ESP32's Serial 2 port on pins 16 & 17, and to the 3V3 and GND pins. 

I recycled my sketch from way back, which was used to configure the GPS receiver in run-time (you can, therefore, use the slightly cheaper module without the battery) and then set about working out why I couldn't get the GarminHud library to run. It turns out that SerialBT's write command isn't quite implemented correctly, so I modified the SendHud function to utilise print instead, which worked.

Version 2 of gabinator and Frank Huebenthal library features a "Down" arrow, which would allow me to implement a GPS compass using the direction arrow function. A gps clock is implemented, a speedometer (in mph, but easily changed to Km/h or knots should the need arise)  and a display of the number of satellites in view (and a warning of no GPS lock) 

There's a slight issue when drawing an "up" arrow. Whatever is written next to the direction display is ignored! This slight bug is overcome by simply writing anything other than "up" twice! 

The sketch (and the required GPS library) can be found on my github here.

The unit is mounted in a box, along with a simple 7805 power supply, and trialled. 

Here's a video of the unit in action. 

... another saved from landfill!