Spi Example Using Gmsl Gui And Evaluation Boards; Spi With And Without Video Running - Analog Devices MAX96752 User Manual

SPI Example using GMSL GUI and Evaluation Boards

• It is recommended to set the SCLK output rate equal or more than the SCLK input rate to avoid buffer overflow
in the SER or DES. The SCLK rate can be set using register writes.
• Disconnect external SPI main device or do not pull CFG pins on SER and DES.
Power up EV boards (ensure that V
• Start GMSL GUI.
• Load GMSL script to enable SPI interface.
• Reconnect external SPI main device.
• Set RO (Read Only) high and write 0xA0, 0xA4(0xA0-0xA3 are used for SPI ID selection, 0xA4 asserts SS1, 0xA5
asserts SS2, and 0xA6 de-asserts both SS1 and SS2).
• As a best practice, before starting SPI data transfer, check BNE (Buffer Not Empty) to ensure that the buffer is
empty. If BNE is high, there is data in the RX buffer that is ready to be read by the external SPI main device. Set
RO high and write FF until BNE = 0.
• Set RO low and start the SPI data transfer.

SPI With and Without Video Running

The SPI Tx FIFO is 16 bytes and Rx FIFO is 32 bytes. The below screenshots show the SPI oscilloscope probes on the
SPI clock and data output (the receiving end at the deserializer). When there is no video through the GMSL link, the
SPI data is transferred consistently without any delay; however, when the GMSL link is utilized 90% by video data,
there may be some intermittent pauses during the SPI data transmission. This is because video data has higher
priority compared to SPI data transfer. The 32-byte buffer compensates for this scheduling delay and makes
continuous streaming of the data possible.
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Figure 19. SPI MFP Pin Settings for MAX96752
on the external SPI main device matches the V
DDIO
on GMSL SER and DES).
DDIO
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