ergodox-firmware/src/keyboard/ergodox/teensy-2-0.md

Documentation : Teensy 2.0

Pinouts and Pin assignments

• + indicates pin
• o indicates unused pin
• -s inserted between some of the pin functions for readability
• OC** pins enclosed in parenthesis had lines over them in the pinout

Teensy 2.0

                          GND +---.....---+ VCC
                       SS PB0 +           + PF0 ADC0
                     SCLK PB1 +           + PF1 ADC1
                     MOSI PB2 +           + PF4 ADC4
                     MISO PB3 +  +     +  + PF5 ADC5
RTS  OC1C  OC0A --------- PB7 + PE6  AREF + PF6 ADC6
           OC0B  INT0 SCL PD0 + AIN0      + PF7 ADC7
                 INT1 SDA PD1 + INT6      + PB6 ADC13 OC1B  OC4B
RXD1 ----------- INT2 --- PD2 +           + PB5 ADC12 OC1A (OC4B)
TXD1 ----------- INT3 --- PD3 +           + PB4 ADC11
     OC3A (OC4A) -------- PC6 +           + PD7 ADC10 T0 -- OC4D
ICP3 ----- OC4A --------- PC7 +-+-+-+-+-+-+ PD6 ADC9  T1 - (OC4D) onboardLED
                 CTS XCK1 PD5 --/ | | | \-- PD4 ADC8 ------------ ICP1
            VCC ------------------/ | \-------------- RST
            GND --------------------/

Teensy 2.0 Pin Assignments

          power_negative  GND +---.....---+ Vcc   power_positive
                column6   PB0 +           + PF0   row6
                              o           + PF1   row7
                              o           + PF4   row8
                              o  o     o  + PF5   row9
                   LED3  OC1C +           + PF6   rowA
                    I2C   SCL +           + PF7   rowB
                    I2C   SDA +           + OC1B  LED2
                column3   PD2 +           + OC1A  LED1
                column4   PD3 +           + PB4   column0
                column1   PC6 +           + PD7   column5
                column2   PC7 +-o-o-o-o-o-o

• notes:
  • SCL and SDA: Need external pull-up resistors. Sometimes the internal pull-ups are enough (see datasheet section 20.5.1), but i think for this project we'll want external ones, in case people want to separate the halves very far.

Notes about Registers

General I/O (see datasheet section 10.2.1)

DDRxn  function  PORTxn  function
1      output    1       drive high
                 0       drive low
0      input     1       internal pull-up on
                 0       internal pull-up off

PINxn  action   function
       write 1  toggles the value of PORTxn
       read     returns the logical value (1|0) of the pin

• notes:
  • Unused pins should be set as input with internal pullup enabled (see datasheet section 10.2.6).
  • We want the row pins 'drive high' initially, and the column pins set as input with internal pull-up. We'll cycle through driving the row pins low, and checking the column pins in the update function.

PWM on ports OC1(A|B|C) (see datasheet section 14.10)

• notes:

  • PWM pins should be set as outputs.
  • we want Waveform Generation Mode 5
    (fast PWM, 8-bit)
    (see table 14-5)
    • set TCCRB[4,3],TCCRA[1,0] to 0,1,0,1
  • we want "Compare Output Mode, Fast PWM" to be 0b10
    "Clear OCnA/OCnB/OCnC on compare match, set OCnA/OCnB/OCnC at TOP"
    (see table 14-3)
    this way higher values of OCR1(A|B|C) will mean longer 'on' times for the LEDs
    • when in a fast PWM mode, set TCCR1A[7,6,5,4,3,2] to 1,0,1,0,1,0
  • we want "Clock Select Bit Description" to be 0b001
    "clkI/O/1 (No prescaling)"
    (see table 14-6)
    • set TCCR1B[2,1,0] to 0,0,1
    • LEDs will be at minimum brightness until OCR1(A|B|C) are changed (since the default value of all the bits in those registers is 0)

• abbreviations:

  • OCR = Output Compare Register
  • TCCR = Timer/Counter Control Register

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Copyright © 2012 Ben Blazak
Released under The MIT License (MIT) (see "license.md") at https://github.com/benblazak/ergodox-firmware