SPRUIL1D May 2019 – December 2024 DRA829J , DRA829J-Q1 , DRA829V , DRA829V-Q1 , TDA4VM , TDA4VM-Q1
The ITU-R BT.656 interface supports either 8-bit or 16-bit processing of input video YCbCr data. See Table 12-1559 for signals used to configure this mode.
Since the data synchronization information is carried along with the data lines, no synchronization signals (that is CCDC_HD, CCDC_VD, and CCDC_FIELD) are necessary in this mode.
Two timing reference codes are transmitted as the synchronization signal. At the start and end of each video data block, two unique codes are sent, respectively. The start code is called the Start of Active Video Signal (SAV), and the end code is called the End of Active Video Signal (EAV). The SAV and EAV codes proceed and follow valid data, as shown in Figure 12-1186. The controller in the VPFE internally bases on SAV and EAV codes to generate the necessary synchronization signals, that is, horizontal sync, vertical sync, and field ID.
Figure 12-1186 BT.656 Signal InterfaceBoth timing reference signals, SAV and EAV, consist of a four-word sequence in the following format: FF 00 00 XY, where FF 00 00 are a set preamble and the fourth word defines the field identification, the state of vertical field blanking, the state of horizontal line blanking, and protection (error correction) codes. The bit format of the fourth word is shown in Table 12-1560 and the definitions for bits, F, V, and H, are given in Table 12-1561. F, V, and H are used in place of the usual horizontal sync, vertical sync, and blank timing control signals. Bits P3, P2, P1, and P0 are protection (error correction) bits for F, V, and H. The relationship the between F, V, and H and the protection (error correction) bits is given in Table 12-1562. To enable error correction, set the VPFE_REC656IF[1] ECCFVH bit. The controller in the VPFE automatically detects and applies error correction when the VPFE_REC656IF[1] ECCFVH bit is set.
| Data Bit Number | First Word (FF) | Second Word (00) | Third Word (00) | Fourth Word (XY) |
|---|---|---|---|---|
| 9 (MSB) | 1 | 0 | 0 | 1 |
| 8 | 1 | 0 | 0 | F |
| 7 | 1 | 0 | 0 | V |
| 6 | 1 | 0 | 0 | H |
| 5 | 1 | 0 | 0 | P3 |
| 4 | 1 | 0 | 0 | P2 |
| 3 | 1 | 0 | 0 | P1 |
| 2 | 1 | 0 | 0 | P0 |
| 1 | 1 | 0 | 0 | 0 |
| 0 | 1 | 0 | 0 | 0 |
| Signal | Value | Command |
|---|---|---|
| F | 0 | Field 1 |
| 1 | Field 2 | |
| V | 0 | 0 |
| 1 | Vertical blank | |
| H | 0 | SAV |
| 1 | EAV |
| F | V | H | P3 | P2 | P1 | P0 |
|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 1 | 1 | 0 | 1 |
| 0 | 1 | 0 | 1 | 0 | 1 | 1 |
| 0 | 1 | 1 | 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 0 | 1 | 1 | 1 |
| 1 | 0 | 1 | 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 | 1 | 0 | 0 |
| 1 | 1 | 1 | 0 | 0 | 0 | 1 |
The controller in the VPFE outputs the XY code in the SAV and EAV into the external memory. In order to eliminate this, set the VPFE_HORZ_INFO[30-16] SPH field to +1. Also set the VPFE_HORZ_INFO[14-0] NPH bitfield to accurately represent the number of active pixels.