Cross-EVK Portability — <alp/board.h> and BOARD_* Aliases

One example, two EVKs. The <alp/board.h> facade plus the portable BOARD_* aliases let the same firmware source build unchanged for both official EVKs — the E1M EVK (35 × 35) and the E1M-X EVK (45 × 65) — for every interface the e1m-spec declares as a common role (STANDARD.md §7.2).

How it works

Three pieces, all generated from board.yaml:

1. ALP_BOARD_<SLUG> compile define — the build emits ALP_BOARD_E1M_EVK or ALP_BOARD_E1M_X_EVK from the board.yaml preset.

2. <alp/board.h> facade — selects the active board's generated routes header from that define:

   #include <alp/board.h>   /* resolves to alp_e1m_evk_routes.h or
                               alp_e1m_x_evk_routes.h at compile time */

   Building without any ALP_BOARD_* define is a compile error with a pointed message — set the example's preset:, or pass -DALP_BOARD_E1M_EVK / -DALP_BOARD_E1M_X_EVK by hand.

3. BOARD_* aliases — each board's routes header defines the same BOARD_* names, mapped to that board's own macros. The mapping comes from the board_alias: field on e1m_routes: entries in the board definition; parity across boards is CI-enforced, so an alias can never silently exist on one EVK only.

#include <alp/board.h>

alp_pwm_t *led = alp_pwm_open(BOARD_PWM_LED_RED, &cfg);   /* builds on both EVKs */

Alias catalogue

Alias	Role	E1M EVK	E1M-X EVK
BOARD_UART_DEBUG	Console UART	EVK_UART_PORT_DEBUG	XEVK_UART_PORT_DEBUG
BOARD_UART_ARDUINO	Arduino UNO UART	EVK_UART_PORT_ARDUINO	XEVK_UART_PORT_ARDUINO
BOARD_I2C_SENSORS	Shared sensor + IO-expander bus	EVK_I2C_BUS_SENSORS	XEVK_I2C_BUS_SENSORS
BOARD_SPI_ARDUINO	Arduino UNO SPI	EVK_SPI_BUS_ARDUINO	XEVK_SPI_BUS_ARDUINO
BOARD_CAN0	CAN-FD bus	EVK_CAN_VEHICLE_BUS	XEVK_CAN_BUS0
BOARD_DAC0	Arduino DAC output	EVK_DAC_ARDUINO_DAC0	XEVK_DAC0
BOARD_DAC1	Audio line out	EVK_DAC_AUDIO_LINE_OUT	XEVK_DAC1
BOARD_I2S_AUDIO	Audio codec / amp bus	EVK_I2S_AUDIO_CODEC	XEVK_I2S_AUDIO
BOARD_PWM_LED_RED / _GREEN / _BLUE	RGB status LED PWM	EVK_PWM_LED_*	XEVK_PWM_LED_*
BOARD_PIN_LED_RED / _GREEN / _BLUE	RGB status LED GPIO	EVK_PIN_LED_*	XEVK_PIN_LED_*
BOARD_PWM_ARD1..3	Arduino PWM headers	EVK_ARD_PWM1..3	XEVK_ARD_PWM1..3
BOARD_ENC_ROTARY	Rotary encoder (PEC12R)	EVK_ENC_ROTARY	XEVK_ENC_ROTARY
BOARD_PIN_ENCODER_SW	Encoder push switch	EVK_PIN_ENCODER_SW	XEVK_PIN_ENCODER_SW
BOARD_PIN_BMI323_INT1	BMI323 data-ready	EVK_PIN_BMI323_INT1	XEVK_PIN_BMI323_INT1

Declaring portability: supported_boards:

A portable example declares the presets it is verified to build for at the top level of its board.yaml:

supported_boards: [e1m-evk, e1m-x-evk]

CI builds one scenario per entry, so portability stays proven rather than claimed. When omitted, the list defaults to the single preset:. This is for examples — per ADR-0011 application firmware still targets one SoM family.

When NOT to use the facade

Form-factor-specific firmware (anything touching pads that exist on only one EVK) should include the specific routes header directly — alp_e1m_evk_routes.h / alp_e1m_x_evk_routes.h — and use the EVK_* / XEVK_* macros. The facade exists for the common-role subset, not as a universal indirection.

See also

• board.yaml reference — board_alias: and supported_boards: fields
• Peripheral I/O — the E1M_* portable pin layer underneath
• EVK page — what each EVK populates