Programmable Scan Mode

This code sample is built on top of Single Image Callbacks example. Most commonly shared functions are omitted for clarity.

First we enumerate all items for PARAM_SCAN_MODE and PARAM_EXPOSE_OUT_MODE parameters using the ReadEnumeration helper function. If any of these parameters is not available, the sample ends with an error. The PARAM_SCAN_MODE is required to demonstrate the scan mode feature. The PARAM_EXPOSE_OUT_MODE is needed to configure the camera expose mode to a scan-specific mode. Once configured, a per-line pulse will be generated on the expose-out pin of the camera output signals. See Scan Mode chapter for detailed description of this feature.

To enable the scan mode, we set the PARAM_SCAN_MODE to PL_SCAN_MODE_PROGRAMMABLE_LINE_DELAY. In the "line delay" mode the PARAM_SCAN_LINE_DELAY parameter will become available for read-write and the delay is represented in number of lines. The PARAM_SCAN_WIDTH will become read-only and its value will be auto-calculated and reported by the camera.

const int32 newScanMode = PL_SCAN_MODE_PROGRAMMABLE_LINE_DELAY;
if (PV_OK != pl_set_param(ctx->hcam, PARAM_SCAN_MODE, (void*)&newScanMode))
{
    PrintErrorMessage(pl_error_code(), "pl_set_param(PARAM_SCAN_MODE) error");
    CloseAllCamerasAndUninit(contexts);
    return APP_EXIT_ERROR;
}
const uns16 newScanLineDelay = 20;
if (PV_OK != pl_set_param(ctx->hcam, PARAM_SCAN_LINE_DELAY,
            (void*)&newScanLineDelay))
{
    PrintErrorMessage(pl_error_code(), "pl_set_param(PARAM_SCAN_LINE_DELAY) error");
    CloseAllCamerasAndUninit(contexts);
    return APP_EXIT_ERROR;
}

We can also configure the camera to flip the scan direction after every frame by writing PL_SCAN_DIRECTION_DOWN_UP to PARAM_SCAN_DIRECTION. In alternate "down-up" scan direction mode we can also reset the direction for every acquisition by writing TRUE to PARAM_SCAN_DIRECTION_RESET or keep the direction unaltered by writing FALSE. See the full sample code for details.

The acquisition is setup using the extended exposure mode, a combination of EXT_TRIG_INTERNAL trigger mode and EXPOSE_OUT_LINE_TRIGGER expose-out mode. In scan mode, the camera can also be triggered externally, in such case, an external trigger mode such as EXT_TRIG_EDGE_RISING should be combined with the EXPOSE_OUT_LINE_TRIGGER option.

const int16 expMode = EXT_TRIG_INTERNAL | EXPOSE_OUT_LINE_TRIGGER;

Once all the settings are applied to the camera, we can read parameters that depend on the setup routine, such as PARAM_SCAN_LINE_TIME or PARAM_SCAN_WIDTH:

long64 newScanLineTimeNs = 0;
if (PV_OK != pl_get_param(ctx->hcam, PARAM_SCAN_LINE_TIME, ATTR_CURRENT,
            (void*)&newScanLineTimeNs))
{
    PrintErrorMessage(pl_error_code(), "pl_get_param(PARAM_SCAN_LINE_TIME) error");
    CloseAllCamerasAndUninit(contexts);
    return APP_EXIT_ERROR;
}
printf("Line time after setup: %lldns\n", newScanLineTimeNs);

uns16 currentScanWidth = 0;
if (PV_OK != pl_get_param(ctx->hcam, PARAM_SCAN_WIDTH, ATTR_CURRENT,
            (void*)&currentScanWidth))
{
    PrintErrorMessage(pl_error_code(), "pl_get_param(PARAM_SCAN_WIDTH) error");
    CloseAllCamerasAndUninit(contexts);
    return APP_EXIT_ERROR;
}
printf("Current scan width: %u\n", currentScanWidth);