I have for some time been a little troubled that GBMINI will not auto-close its windows – we know that the MINI can automatically do this, since English & European MINIs do – presumably litigation risks in USA forced MINI USA to disable this feature.
Originally, while trying to crack the crack the rear fog light functionality in the MINI last year, I had hoped to discover the auto-up function too – but it appears that the MINI software is protected by both “SA” flags and some sort of “country code”.
So I decided to make a little circuit that would provide this feature for GBMINI! Nothing more complex than a small processor and some interface circuits – easy! Or so I thought. I made a circuit which simulates holding the window up toggle switch closed for a while, to allow the window to close; the MINI circuits detect when the window is closed and switch the motor off to prevent damage. I used a special “double-click” of the switch to guard against someone else accidentally and unexpectedly activating the new feature.
Developing the first working version
I began with a PIC16HV540 which was supposed to directly handle the 12V levels in a car;
my first design demonstrated that the existing MINI circuits were not keen on having other circuits added to them – I lost the ability to open or close windows, doors, etc!
I updated the design but while waiting for the second set of boards to arrive, the HV540 in the test circuit in GBMINI smoked!
Apparently the Microchip HV design is not robust enough to live in a car after all (in their defence they do not say it is suitable for cars, but they do tout its 12V capabilities …
So back to the drawing board again for the third design – now using a normal 5V level PIC with a LM317 pre-regulator, and all the necessary interface circuits to fool the MINI into thinking nothing has changed … I ordered five circuit boards from Bare Bones PCBs for $50, received them in about 3 days, built one and tested it (pictured above).
The circuit worked fine on the bench, so I installed it in GBMINI and tested it; the circuit installs between the toggle switch panel and the car harnesses; an 18 way connector (the black one) is removed from the back of the toggle switch panel and connected to the circuit; a new 18 way connector-to-connector harness I made then goes from the circuit to the toggle switch panel:
The wiring and circuit design allows the PIC to detect when the toggle switches are activated by the driver; it can also simulate their action!
I have programmed the PIC to register a quick double click of the close/up window switch (for the driver and passenger sides); the circuit then maintains the switch active for 6s while the window closes.
If the driver hits the down switch during the 6s, the auto-up is cancelled. Although the circuit has no way to detect when the window is fully closed, the existing MINI circuits do this and switch the motor off – the circuit fools the car into thinking the driver is simply holding the switch closed.
Another function I included in the original circuit provides a “closure” signal to activate a remote garage door opener. If the door unlock toggle switch is held for more than 0.5s, an opto-coupled signal is generated which can be wired to the garage door opener to trigger its function.
This will hopefully provide a tidy garage door opener install in my friend Gavins MINI.
On the pictures you might see un-populated areas for additional circuits, intended to provide a “switched 12V” to control, for example, a radar detector which could be turned on/off using a toggle switch. I don’t need this function, but my friend Ivan does!
A little bit of electronic fun 🙂
M&I / GBMINI 