RM0390 Rev 4 1269/1328
RM0390 HDMI-CEC controller (HDMI-CEC)
1283
Figure 437. Arbitration phase
The Figure 438 shows an example for a SFT of three nominal bit periods
Figure 438. SFT of three nominal bit periods
A configurable time window is counted before starting the transmission.
In the SFT=0x0 configuration the HDMI-CEC device performs automatic SFT calculation
ensuring compliance with the HDMI-CEC Standard:
• 2.5 data bit periods if the CEC is the last bus initiator with unsuccessful transmission
• 4 data bit periods if the CEC is the new bus initiator
• 6 data bit periods if the CEC is the last bus initiator with successful transmission
This is done to guarantee the maximum priority to a failed transmission and the lowest one
to the last initiator that completed successfully its transmission.
Otherwise there is the possibility to configure the SFT bits to count a fixed timing value.
Possible values are 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5 data bit periods.
32.4.1 SFT option bit
In case of SFTOPT=0 configuration SFT starts being counted when the start-of-
transmission command is set by software (TXSOM=1).
In case of SFTOPT=1, SFT starts automatically being counted by the HDMI-CEC device
when a bus-idle or line error condition is detected. If the SFT timer is completed at the time
TXSOM command is set then transmission starts immediately without latency. If the SFT
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