Quick Start Guide for the Peripheral Event Controller Driver

This is the quick start guide for the SAM4L Peripheral Event Controller (PEVC) Driver, with step-by-step instructions on how to configure and use the driver for a specific use case.

The use cases contain several code fragments. The code fragments in the steps for setup can be copied into a custom initialization function, while the steps for usage can be copied into, e.g., the main application function.

Use Cases

• Basic Use Case

Basic Use Case

This use case will demonstrate how to use the Peripheral Event Controller on SAM4L_EK. In this use case, one Event Channel is configured as:

• Configure AST periodic event 0 as a generator
• Configure PDCA channel 0 as a user to transfer one word
• Enable the event shaper for the generator

Setup Steps

Prerequisites

This module requires the following service:

• Clock Management (Sysclock)

Code Example

Copy-paste the following setup code to your application:

static void init_events(void)
{
    struct events_conf    events_config;
    struct events_ch_conf ch_config;

    /* Initialize event module */
    events_get_config_defaults(&events_config);
    events_init(&events_config);
    events_enable();

    /*
     * Configure an event channel
     * - AST periodic event 0 --- Generator
     * - PDCA channel 0       --- User
     */
    events_ch_get_config_defaults(&ch_config);
    ch_config.channel_id = PEVC_ID_USER_PDCA_0;
    ch_config.generator_id = PEVC_ID_GEN_AST_2;
    ch_config.shaper_enable = true;
    ch_config.igf_edge = EVENT_IGF_EDGE_NONE;
    events_ch_configure(&ch_config);

    /* Enable the channel */
    events_ch_enable(PEVC_ID_USER_PDCA_0);
}

Add this to the main loop or a setup function:

    /* Initialize AST as event generator. */
    init_ast();

    /* Initialise events for this example. */
    init_events();

    /* Initialize the PDCA as event user */
    init_pdca();

Workflow

1. Initialize AST to generate periodic event 0. see sam/drivers/events/example1 for more detail:

       init_ast();

2. Initialize the event module and enable it:

       init_events();

3. Initialize PDCA channel 0 to transfer data to USART. see sam/drivers/events/example1 for more detail:

       init_pdca();

Basic Usage

After the channel is configured correctly and enabled, each time a new event from AST occurs, a character is sent to the USART via PDCA without the use of the CPU.