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DS90UB948-Q1: How to compute the FC delay and BC delay of GPIO

Sherry Liang
Genius 10255 points
Part Number: DS90UB948-Q1

Dear team,

How to compute the transmit delay of forward channel GPIO (pass through from 941's GPIO to 948's GPIO) and back channel GPIO (pass through from 948's GPIO to 941's GPIO) ?

Thanks & Best Regards,

Sherry

  • 0
    TI__Guru 66820 points

    Hi Sherry, 

    FC_Delay = Period of the FC Frame Rate

        a) Data is sent across the FC in frames. A single FC frame consists of 35 bits containing RGB, GPIO, I2C, sync signals, etc...

        c) You need to wait for at least one frame to be sent over the FC. This is the FC delay.

        f) To calculate the FC frame rate, you divide your configured FC frequency by 35 bits. (Frame Rate = FC freq [bits/sec] / 35 [bits/frame])

        g) Then, you calculate the Period to get the FC_Delay (Period = 1 / (Frame Rate)). Multiply by 2 to calculate for the worst case.

    BC_Delay = Period of the BC Frame Rate

        a) The BC transmits data in 30-bit frames. The time it takes for one full frame to travel across the BC is the BC Delay.

        b) Normally, you need to calculate the worst case scenario, which is how long it takes for 2 frames to travel across the BC.

        c) To calculate the BC frame rate, you divide your configured BC frequency by 30 bits. (Frame Rate = BC freq [bits/sec] / 30 [bits/frame])

    Regards,

    Logan