• Porting our original indicator project to Atmel family controller and changing some of the fundemental operation of how the inputs  are done. Also as we wanted a multi-color display the borrowed LED matrix from other project uses bi-color LED chips turning the  display in essence to 3 colors or a pattern of combination of the 2 colors by enabling or disabling particular pixel color. More on that in the software function.
  
  The original design relied on too many connections between the controller and display it self, 12 for the display and 9 for selector for 6 speed manual transmission. The count would be less for say 5 speed or automatic transmissions.
  
  In this design, display had been separated onto its own pcb board which contains some logic chips to drive the LEDs and a processor board containing naturally the processor, voltage regulator and sensors/switches connections. Additionally inputs are triggered by grounding it rather then connecting to the matrix logic making it safer triggers and possibly avoiding damaging the processor or display or both by incorrect wiring.
  
  To help in the design, hall effect sensors that are used for detecting which gear the transmission is in have open collector so they can safely be wired directly into the processor with some safety in mind.
  
  To help with wiring and packaging of it all, it was decided to split the project into 2 parts not counting the hall effect sensors as location of them would be different for each and different shifter design. So a connector for sensor harness is provided for each sensor and simply the hall sensor board is either soldered directly to the wires or plugged via connector or a combination of.
  As the processor board would require most of the wiring it was decided that it would be located somewhere with in the tunnel under the shifter boot and a thin cable be running from it to the shifter knob where drive circuitry be located for the display and display board it self. Not closed of to option the display could be located outside of the shift knob it self if one preffers.
  
  
  
  Processor board
  Build around ATmega4808, the board was build specifically for this purpose, though it may serve other purposes possibly in the future projects.  The processor is ideal for this purpose as it has build in clock to run at very fast frequency and large number of I/O pins all packaged in a very small surface mounted chip requiring very little external passive components making the circuit  simplified and compact. With 14 possible inputs for gear selections or other digital inputs  SPI connector to the display and additional serial and I2C ports provided through additional second connector for expansions or possibly driving different sub boards like OLED displays.
  To power the board from 12V car power system, onboard 5v regulator produces stable supply to the processor and accompanying circuitry.
  For any one wishing to expand connection of the board into cars communication systems it can be interfaced via Single Wire low speed CAN or faster high speed CAN transceivers. However as they are fired to same CAN UART, only one of the transceivers can be used at a time.
   

  
  
  Display
  The LED matrix uses 35 0606 led chips however they are 4 pin with 2  leds per package making 70 in total. To make it more interesting is that the colors are wired independantly so in essence has two independent 5x7 matrices of 2 colors. But the neet thing is that they can be rotated 180 degrees and primary colors would change.
  
  To drive the 35 or 70 LEDS a row colum drivers are required for which there are just as many drivers options. Using a set of shift registers for simple interface and 16 bits.  With 12 bits (7 rows 5 columns) required for each matrix provides a bit of an issue to drive 2 of those matrixes. However adding 2 buffers as parallel to the first shift register and wiring enable pin to second register different bit allows for enabling each color with once single column scan
  
  For a very compact packaging of the 2 boards and to eliminate any possible connectors the shift register board had been designed in a way to contain all the components on one side and have interconnecting solder pads on other side. This provides a way to solder the display board to the decoder board making a single dual sided board
  
  The 74hc595 registers on the control board alone are responsible for decoding of which pixel is activated in the matrix. The as the data is being shifted out its selecting row on one register and column on second register with last 2 most significant bits controlling which color is selected by means of activating buffers on the 74hc244 driver.
  
  
  Assembly of the display board was designed to fit into our custom shift knobs. We will be producing boards with mounting holes in the future and on request.
  
  
  
   

  
  Software
  The decoded or shift register board is designed around 2 shift registers and 2 buffers enabling respective colors. So basically whats needed is a scanner of rows and colums. One register controls which row is active and the other register controls which dots in the row to turn on and which color to enable.
  
  A sample pattern  for letter 'N' is below. With MSB on left controlling the color buffers and bit 6 & 7 high turn on both buffers thus mixing colors resulting in purple from red & blue combination
  
  This is a pattern of N
  B01x10001, // Row 1: * *
  B01x11001, // Row 2: ** *
  B01x10101, // Row 3: * * *
  B01x10011, // Row 4: * **
  B01x10001, // Row 5: * *
  B01x10001, // Row 6: * *   x
  B01x10001 // Row 7: * *
  
  The provided sample code writen for manual transmission and as it would be hard to sense neutral position, we are defaulting N when nothing is sensed. This way we will have N when in neutral and in between switching gears. When any other gear is selected respective pattern will be selected and sent to the display. 
  The program can be very easily adapted to automatic transmission just by switching character pattern.
  
  The code however is not suitable for sequential transmissions like you find it in motorbikes. as you would need to keep track which gear the bike is in and change based on shift.
  
  
  
  Features

     3 color mixing
     lower wire count interconnection between processor and display
     safer trigger inputs by utilizing hall effect sensors
     processor board features Single wire GMLAN 33.3Kb or flex CAN drivers
     fast ATmega4808 processor  
    
   

  Documents

     Schematics
        LED

        Shift register board
        Processor board

     PCB layout
        Shift register board  Gerber files
        Processor board Gerber files
        hall effect board
     Bill of Materials
     Sample program  ATmega328P no CAN implementation
     Processor board  3d STL files
     Shifter knob sample
     Display board cavity requirement example