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GS1500 数据表(PDF) 10 Page - Gennum Corporation |
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GS1500 数据表(HTML) 10 Page - Gennum Corporation |
10 / 17 page GENNUM CORPORATION 522 - 33 - 00 10 NOTE: If a simultaneous FIFO read and write operation is to be performed, the FF_STA[2:0] outputs should not be used as they may indicate incorrect FIFO status. 6.2. ANC/DATA Extraction When the control signal ANC/DATA is high and WEN is low, the device detects the ANC data header and extracts the ANC data (including the header) when these data are present in the video streams. When ANC/DATA and WEN are both low, the device extracts all original video data into the FIFO. To ensure ANC data extraction from the LUMA or CHROMA channels, empty (unload) the ANC data from the respective FIFO buffer during the active video portion of the data streams. ANC data is extracted from a video stream and written into the corresponding internal FIFO buffer until it is completely full. When a FIFO buffer is full, the FF_STA[2:0] signal is set to 110. The device provides ANC data copying capability as an alternative to extraction. When EX/CP is high, the extraction function is enabled. The device replaces the extracted data in the video streams with their respective blanking levels. If EX/CP is low, the copy function is enabled. All the original data remain in the video stream after copying them into the FIFO buffer. To extract ANC data from the HANC region only, the device provides an automated extraction mode. When the control signal FM_I/E is high, the FIFO control signals FFRST and WEN cannot be used. In this mode of operation, the device generates reset and enable signals internally, which allows an automated extraction of ANC data from HANC region of the incoming LUMA and CHROMA data streams. The user must supply a proper REN signal to enable the access of ANC data stored in the FIFO. These data should be read out of the FIFO during the active video period. Once all words have been read from the FIFO, the FF_STA signal is set to 001. If the user has not emptied the FIFO by the time the next HANC period begins, all data within the FIFO is discarded and the FIFO resets so that read and write address pointers are at their starting position. When the control signal FM_I/E is low, the user has full control over reading from and writing to the FIFO, including the FIFO reset (FFRST) and FIFO write enable (WEN). The ANC data output ANC_OUT[9:0] can be set to a high Z state with the FOEN control signal. When FOEN is low, the ANC_OUT[9:0] outputs are enabled. When FOEN is high, the ANC_OUT[9:0] outputs are in a high Z state. Internal read address pointers are incremented regardless of the state of FOEN when REN is low. 6.3. FIFO Read Control The FIFO control signal REN is the read enable signal used to access ANC data in the internal FIFO through the FIFO interface. The user can access only one of the two internal FIFO buffers at a time. The LUMA FIFO can be read when ANC_Y/C is high. The CHROMA FIFO can be read when ANC_Y/C is low. When the internal FIFO is not in the empty or underrun states, it is ready to provide ANC data to the user. At this point, the user should read up to 1024 data words from each FIFO through the FIFO interface. When REN is low and a rising edge on R_CLK is detected, the device outputs the next word stored in the FIFO. Each time R_CLK is toggled while REN is low, the internal read address pointer (LUMA or CHROMA) is incremented. When REN is high, the read address pointer is not incremented. 6.4. FIFO Write Control The FIFO control signal WEN is the write enable signal. It enables the ANC data extraction from either the LUMA or the CHROMA video streams into the internal respective FIFO buffers. When WEN is LOW, the write address pointer increments with the internal clock at the video data rate. When WEN is HIGH, the write address pointer does not increment. To reset both address pointers for read and write to their starting positions, toggle the FIFO reset signal FFRST from high to low. 6.5. FIFO External Reset In external FIFO control mode, the internal FIFO address pointers are reset to zero (0) using FFRST. A recommended external reset process is shown in Figure 16. 7. READING CRC ERROR FLAGS The GS1500 provides error flags which track the Cyclic Redundancy Code embedded in each line of LUMA and CHROMA video streams (LINE_CRC_ERR_Y and LINE_CRC_ERR_C, respectively). NOTE: For users monitoring the status of the CRC error flags, it is strongly recommended that they are read only when FOEN is low. |
类似零件编号 - GS1500 |
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类似说明 - GS1500 |
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