.. _lang-board-values: Board-Specific Values ===================== There are a number of board-specific values: constants or variables which are different depending on which LeafLabs board you have. The exact values for each board are given in your :ref:`board's hardware documentation `. This page lists and documents the board-specific values. You should use these when appropriate in your own programs. This will help make it easier to share your code with other people who have different boards. Some example usages are given :ref:`below `. The actual values for each board are given in the :ref:`Board Hardware Documentation `. .. contents:: Contents :local: Constants --------- - ``CYCLES_PER_MICROSECOND``: Number of CPU cycles per microsecond on your board. - ``CLOCK_SPEED_MHZ``: Clock speed of your board, in megahertz (MHz). This is the same as ``CYCLES_PER_MICROSECOND``. - ``CLOCK_SPEED_HZ``: Clock speed of your board, in hertz (Hz). This is the same as ``CLOCK_SPEED_MHZ`` × 1,000,000. - ``SYSTICK_RELOAD_VAL``: Value used when reloading the :ref:`systick` timer's counter [#fmillis]_. .. _lang-board-values-but: - ``BOARD_BUTTON_PIN``: Pin connected to the built-in button (labeled "BUT" on your board's silkscreen). .. _lang-board-values-led: - ``BOARD_LED_PIN``: Pin connected to the built-in LED. - ``BOARD_NR_GPIO_PINS``: Total number of :ref:`GPIO pins ` that are broken out to headers. Some of these might already be connected to external hardware (like the built-in LED and button). To find out if a pin is in use, see :ref:`boardUsesPin() ` (and also :ref:`boardUsedPins `). .. _lang-board-values-nr-pwm-pins: - ``BOARD_NR_PWM_PINS``: Total *number* of GPIO pins that can be used for :ref:`PWM `. The actual *pins* that can do PWM are in the :ref:`boardPWMPins ` array. .. _lang-board-values-nr-adc-pins: - ``BOARD_NR_ADC_PINS``: Total number of GPIO pins that can be used for :ref:`analog-to-digital conversion `. The actual pins that can do ADC conversion are in the :ref:`boardADCPins ` array. .. _lang-board-values-nr-used-pins: - ``BOARD_NR_USED_PINS``: Total number of GPIO pins that are already connected to some external hardware (like a built-in LED) on the board. The actual pins that that are already used are in the :ref:`boardUsedPins ` array. To see if a pin is already in use, use the :ref:`boardUsesPin() ` function. .. _lang-board-values-usart: - :ref:`USART ` (serial port) related constants: * ``BOARD_USART1_TX_PIN``, ``BOARD_USART2_TX_PIN``, ``BOARD_USART3_TX_PIN``: TX pins for the 3 USARTS. * ``BOARD_USART1_RX_PIN``, ``BOARD_USART2_RX_PIN``, ``BOARD_USART3_RX_PIN``: RX pins for the 3 USARTS. * ``BOARD_UART4_TX_PIN``, ``BOARD_UART5_TX_PIN``: TX pins for UARTs 4 and 5 (high-density boards like Maple Native only). * ``BOARD_UART4_RX_PIN``, ``BOARD_UART5_RX_PIN``: RX pins for UARTs 4 and 5 (high-density boards like Maple Native only). * ``BOARD_NR_USARTS``: Number of serial ports on the board. This number includes UARTs 4 and 5 if they are available. - :ref:`SPI ` related constants: * ``BOARD_SPI1_NSS_PIN``, ``BOARD_SPI1_MOSI_PIN``, ``BOARD_SPI1_MISO_PIN``, ``BOARD_SPI1_SCK_PIN``: SPI1 peripheral's NSS, MOSI, MISO, and SCK pins, respectively. * ``BOARD_SPI2_NSS_PIN``, ``BOARD_SPI2_MOSI_PIN``, ``BOARD_SPI2_MISO_PIN``, ``BOARD_SPI2_SCK_PIN``: SPI2 peripheral's NSS, MOSI, MISO, and SCK pins, respectively. * ``BOARD_SPI3_NSS_PIN``, ``BOARD_SPI3_MOSI_PIN``, ``BOARD_SPI3_MISO_PIN``, ``BOARD_SPI3_SCK_PIN``: SPI3 peripheral's NSS, MOSI, MISO, and SCK pins, respectively (available on high-density devices like Maple Native and Maple RET6 edition only). * ``BOARD_NR_SPI``: Number of SPI peripherals on the board. .. _lang-board-values-debug: - Debug (JTAG, SW-Debug) related constants: ``BOARD_JTMS_SWDIO_PIN``, ``BOARD_JTCK_SWCLK_PIN``, ``BOARD_JTDI_PIN``, ``BOARD_JTDO_PIN``, and ``BOARD_NJTRST_PIN``. These constants are the pin numbers for :ref:`GPIOs ` used by the :ref:`jtag` and Serial-Wire Debug peripherals. Except for the Maple Mini, these pins are usually reserved for special purposes by default (i.e., they are in :ref:`boardUsedPins `). However, they can be used as ordinary GPIOs if you call the :ref:`lang-disabledebugports` function. (Be careful with this on the Maple, as writing to ``BOARD_NJTRST_PIN`` may cause your board to reset!). .. _lang-board-values-pwm-pins: .. _lang-board-values-adc-pins: .. _lang-board-values-used-pins: Pin Arrays ---------- Some :ref:`arrays ` of pin numbers are available which you can use to find out certain important information about a given pin. - ``boardPWMPins``: Pin numbers of each pin capable of :ref:`PWM ` output, using :ref:`pwmWrite() `. The total number of these pins is :ref:`BOARD_NR_PWM_PINS `. - ``boardADCPins``: Pin numbers of each pin capable of :ref:`ADC ` conversion, using :ref:`analogRead() `. The total number of these pins is :ref:`BOARD_NR_ADC_PINS `. - ``boardUsedPins``: Pin numbers of each pin that, by default, is used for some special purpose by the board. The total number of these pins is :ref:`BOARD_NR_USED_PINS `. To check if a pin is used for a special purpose, use :ref:`boardUsesPin() `. .. _lang-board-values-examples: Examples -------- :ref:`BOARD_LED_PIN ` On the Maple, the built-in LED is connected to pin 13. On the Maple Mini, however, it is connected to pin 33. You can write a "blinky" program that works on all LeafLabs boards using ``BOARD_LED_PIN`` and :ref:`toggleLED() `:: void setup() { pinMode(BOARD_LED_PIN, OUTPUT); } void loop() { toggleLED(); delay(100); } :ref:`BOARD_BUTTON_PIN `: Similarly, you can write a single program that prints a message whenever the button is pressed which will work on all LeafLabs boards using ``BOARD_BUTTON_PIN`` and :ref:`isButtonPressed() `:: void setup() { pinMode(BOARD_BUTTON_PIN, INPUT); } void loop() { if (isButtonPressed()) { SerialUSB.println("You pressed the button!"); } } See Also -------- - :ref:`lang-boardusespin` - :ref:`lang-isbuttonpressed` - :ref:`lang-waitforbuttonpress` - :ref:`lang-pinmode` - :ref:`lang-toggleled` - :ref:`lang-analogread` - :ref:`lang-pwmwrite` - :ref:`lang-enabledebugports` - :ref:`lang-disabledebugports` .. rubric:: Footnotes .. [#fmillis] In order for :ref:`lang-millis` to work properly, this must be ``CYCLES_PER_MICROSECOND`` × 1,000 - 1.