CPC GPIO Secondary#

CPC GPIO Expander Secondary Device API.

The CPC GPIO Secondary API provides functions to initialize and manage the GPIO endpoint on the secondary device (Silicon Labs microcontroller). This allows a CPC host (primary device) to discover and control GPIO pins through the CPC protocol.

Overview#

The CPC GPIO Expander enables a CPC host to access GPIO pins on a Silicon Labs microcontroller (secondary device) through the Co-Processor Communication (CPC) protocol. The secondary device exposes GPIO pins as a CPC endpoint that can be discovered and controlled by the host.

Initialization#

The component automatically registers event handlers that integrate with the Silicon Labs platform's service initialization system (sl_main):

• **service_init event**: Automatically calls sl_cpc_gpio_expander_init() during system initialization via sl_main_init()

• **service_process_action event**: Automatically calls sl_cpc_gpio_expander_process_action() during the main loop via sl_main_process_action()

You do not need to manually call these functions - they are handled automatically by the platform's service system.

Processing Commands#

The method for processing incoming GPIO commands depends on whether a kernel/RTOS is present:

Bare-metal Applications: The sl_main_process_action() function must be called in the main loop, which automatically calls sl_cpc_gpio_expander_process_action() through the event handler system.

Kernel/RTOS Applications: When using a kernel or RTOS, processing is handled automatically by a background task created during initialization. The service_process_action event handler is not used in RTOS applications.

This function handles all GPIO operations including:

• Reading GPIO values

• Setting GPIO values

• Configuring GPIO pins (bias, drive mode)

• Setting GPIO direction (input/output)

Example Usage#

Bare-metal Application:

#include "sl_main_init.h"
#include "sl_main_process_action.h"

int main(void)
{
  // Automatically calls sl_cpc_gpio_expander_init() via service_init event
  sl_main_init();

  app_init();

  while (1) {
    // Automatically calls sl_cpc_gpio_expander_process_action() 
    // via service_process_action event
    sl_main_process_action();

    app_process_action();
  }
}
#include "sl_main_init.h"
#include "sl_main_process_action.h"

int main(void)
{
  // Automatically calls sl_cpc_gpio_expander_init() via service_init event
  sl_main_init();

  app_init();

  while (1) {
    // Automatically calls sl_cpc_gpio_expander_process_action() 
    // via service_process_action event
    sl_main_process_action();

    app_process_action();
  }
}

Kernel/RTOS Application:

#include "sl_main_init.h"

int main(void)
{
  // Automatically calls sl_cpc_gpio_expander_init() via service_init event
  // Background task is created automatically for processing
  sl_main_init();

  app_init();

  while (1) {
    app_process_action();
  }
}
#include "sl_main_init.h"

int main(void)
{
  // Automatically calls sl_cpc_gpio_expander_init() via service_init event
  // Background task is created automatically for processing
  sl_main_init();

  app_init();

  while (1) {
    app_process_action();
  }
}

Note: You do not need to include sl_cpc_gpio_expander.h or manually call the initialization/process functions. These are handled automatically by the platform's service system.

Modules#

sl_cpc_gpio_expander_handle_t