Digital Speedo
After the
problems with the mechanical speedo (in 2005) I decided to build an electronic
one. I used an Atmel AVR ATTINY2313 processor and based the software on some
example code published in EDN.
Atmel ATTINY2313
The ECM in
my S4 generates 4000 pulses/km, and with this information I computed the
calibration constants to convert the measured time between two pulses from the
ECM into kmh. Checked it using a GPS and it works perfectly.
This is the
first prototype being tested
I also
built one with a different, larger LCD (below). In the end, I used a blue LCD
and put the new speedometer at the location of the digital clock
After the
mechanical speedo broke down the second time (a hot day again), I replaced the
digital clock in the dash with a 2 line blue-white LCD that shows both the
digital speed and the distance traveled. The following four pictures show the
installation and the result.
LCD speedo
without frame. LCD
speedo with frame installed