该部分代码实现在app_adc.c文件中是开源，可以直接移植到旧版本的SDK上应用，回调函数只是通知ADC采样完成，应用示例代码如下：

回调函数：

void app_adc_evt_handler(app_adc_evt_t * p_evt)
{
    if (p_evt->type == APP_ADC_EVT_CONV_CPLT)
    {
        covn_done = 1;
        printf("DMA conversion is done.\r\n");
    }
}

多通道采集示例：

void adc_multi_sample_case(void)
{
    double   voltage[TEST_CONV_LENGTH];

    app_adc_params_t params_t = DEFAULT_PARAM_CONFIG;

    app_adc_deinit();
    app_adc_init(¶ms_t, app_adc_evt_handler);

    app_adc_samle_node_t sample_node0;
    sample_node0.channel = ADC_INPUT_SRC_IO0;
    sample_node0.p_buf   = &adc_channel0_buf[0];
    sample_node0.len     = TEST_CONV_LENGTH;

    app_adc_samle_node_t sample_node1;
    sample_node1.channel = ADC_INPUT_SRC_IO1;
    sample_node1.p_buf   = &adc_channel1_buf[0];
    sample_node1.len     = TEST_CONV_LENGTH;

    sample_node0.next = &sample_node1;

    memset(adc_channel0_buf, 0, sizeof(adc_channel0_buf));
    memset(adc_channel1_buf, 0, sizeof(adc_channel1_buf));
    covn_done = 0;
    app_adc_multi_channel_conversion_async(&sample_node0, 2);
    while(covn_done == 0);

    app_adc_voltage_intern(adc_channel0_buf, voltage, TEST_CONV_LENGTH);
    printf("Channel 0 value:\r\n");
    for(uint32_t i = 3; i < TEST_CONV_LENGTH; i++)//ignore the first 3 abnormal values
    {
        printf("%0.3fV  ", voltage[i]);
        delay_us(1000);
    }
    printf("\r\n\r\n");

    app_adc_voltage_intern(adc_channel1_buf, voltage, TEST_CONV_LENGTH);
    printf("Channel 1 value:\r\n");
    for(uint32_t i = 3; i < TEST_CONV_LENGTH; i++)//ignore the first 3 abnormal values
    {
        printf("%0.3fV  ", voltage[i]);
        delay_us(1000);
    }
    printf("\r\n\r\n");
}