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Pinout and Pin assignments

  • + indicates connected pin
  • o indicates unconnected pin
  • = is used to list other things the pin is connected to
  • -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
                column_7  PB0 +           + PF0  row_5
                column_8  PB1 +           + PF1  row_4
                column_9  PB2 +           + PF4  row_3
                column_A  PB3 +  o     o  + PF5  row_2
            (OC1C) LED_3  PB7 + PE6  AREF + PF6  row_1
             (SCL)   I2C  PD0 +           + PF7  row_0
             (SDA)   I2C  PD1 +           + PB6  LED_2 (OC1B)
                column_B  PD2 +           + PB5  LED_1 (OC1A)
                column_C  PD3 +           + PB4  = Vcc
                column_D  PC6 +           o PD7
                          PC7 o-o-o-o-o-o-+ PD6  onboardLED = GND
                          PD5 --/ | | | \-- PD4
                          Vcc ----/ | \---- RST
                          GND-------/

  • Notes:

    • Row and column assignments are to matrix positions, which may or may or may not correspond to the physical position of the key: e.g. the key where row_4 and column_2 cross will be scanned into the matrix at [4][2], wherever it happens to be located on the keyboard. Mapping from one to the other (which only matters for defining layouts) is handled elsewhere.

    • LEDs are labeled using numbers (starting with '1') instead of letters (starting with 'A') as on the the prototype PCB by Fredrik (late 2012).

    • SCL and SDA (pins D(0) and D(1)) need external pull-up resistors. Sometimes the Teensy internal pull-ups are enough (see datasheet section 20.5.1), but i think for this project we'll want external ones. The general recommendation for 400kHz I²C seems to be 2.2kΩ.

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

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

TCCR1A : Timer/Counter 1 Control Register A
.---------------------------------------------------------------------.
|   7    |   6    |   5    |   4    |   3    |   2    |   1   |   0   |
|---------------------------------------------------------------------|
| COM1A1 | COM1A0 | COM1B1 | COM1B0 | COM1C1 | COM1C0 | WGM11 | WGM10 |
'---------------------------------------------------------------------'

TCCR1B : Timer/Counter 1 Control Register B
.------------------------------------------------------------------.
|   7   |   6   |    5     |   4   |   3   |   2   |   1   |   0   |
|------------------------------------------------------------------|
| ICNC1 | ICES1 | Reserved | WGM13 | WGM12 |  CS12 |  CS11 |  CS10 |
'------------------------------------------------------------------'

* We want:
    * `WGM` = `0b0101` : Fast PWM mode, 8-bit (see section 14.8.3)
    * `COM1(A|B|C)` = `0b10` : Clear OC1(A|B|C) on compare match, set
      OC1(A|B|C) at TOP
        * That is, we want `TCCR1A |= 0b10101000`
        * This way higher values of `OCR1(A|B|C)` will mean longer 'on'
          times for the LEDs (provided they're hooked up to GND; other way
          around if they're hooked up to Vcc)
    * `CS` = `0b001` : clk_i/o / 1 (no prescaling)
        * 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`)

  • Notes:

    • PWM pins should be set as outputs.

    • The pins source current when on, and sink current when off. They aren't set to high impediance for either.

    • In Fast PWM mode, setting OCR1(A|B|C) to 0 does not make the output on OC1(A|B|C) constant low; just close. Per the datasheet, this isn't true for every PWM mode.

  • Abbreviations:

    • COM: Compare
    • CS: Clock Select
    • ICES: Input Capture Edge Select
    • ICNC: Input Capture Noise Canceler
    • OCR: Output Compare Register
    • `TCCR: Timer/Counter Control Register
    • WGM: Waveform Generation Module

Copyright © 2012 Ben Blazak benblazak.dev@gmail.com
Released under The MIT License (see "doc/licenses/MIT.md")
Project located at https://github.com/benblazak/ergodox-firmware