Receiver enters free run when the TMDS clock is not detected or when the detected input format does not match the format indicated by the PRIM_MODE [3:0] and VID_STD [5:0] settings. • For example, if input video is not present. It controls the default color insertion and causes the receiver to generate a default clock. • Free run feature is not configured automatically for HDMI modes and it can be enabled using register 0xBA.
Below are the functionality that uses in free run.
MANUAL COLOR SELECTION: CP_DEF_COL_MAN_VAL bit high enables the user to overwrite the default colors with the values given in DEF_COL_CHA[7:0], DEF_COL_CHB[7:0], and DEF_COL_CHC[7:0]. These parameters DEF_COL_CHA[7:0], DEF_COL_CHB[7:0], and DEF_COL_CHC[7:0] allows the user to specify their own default color values.
FORCE FREE RUN: Free run can be generated even if there is valid video on its inputs.When CP address register 0xBF is set to 1, the CP core is forced to free run which means free run mode is active even when video is being received.
CUSTOM PROGRAM: It is also possible to custom program the free run resolution by programming the line length, line count max and interlaced registers.For video standards other than the preprogrammed settings of PRIM_MODE[3:0] and VID_STD[5:0], the above parameters can be set manually.
DIS_AUTO_PARAM_BUF: DIS_AUTO_PARAM_BUFF- 0 Buffer the last measured parameters in HDMI mode used to determine video resolution the part free runs into. Buffered free run happens when the input was removed after having been connected. DIS_AUTO_PARAM_BUFF -1 Disable the buffering of measured parameters in HDMI mode. Free run standard determined by PRIM_MODE [3:0], VID_STD [5:0] and V_FREQ [2:0].If not in buffered free run, the video -standard (VID_STD/CP_VID_STD) parameters are used to generate the free-run video.Non buffered free-run happens when no input was ever connected or when the device is free running with DIS_AUTO_PARAM_BUFF to 1.This mode (that is, DIS_AUTOPARAM_BUFFER = 1) does not support HDMI input with deep color.
Note: Without free-run mode, these output signals are not stabilized when the input signal is lost or does not match what is expected. To validate the Rx part, We can use free run as for default color output. It can be generated through component processor (CP).