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DS90UB935-Q1: Can not lock with ti954 in synchronous mode,but non-synchronous internal clock mode is ok

ni ni
Prodigy 60 points
Part Number: DS90UB935-Q1


hi! I'm debugging a new project recently. The ser is ti935 and the deser is ti954. According to the specification of 935, it can work in multiple modes. I configure it as non-synchronous internal clock mode. TI954 can show color bar, but TI935 (IIC) cannot be configured through 954 by fpdlink back channel. If the mode of 935 is configured as synchronous mode, the 954 cannot lock. Replace another 935 board (from someone else's), which can work normally in synchronous and asynchronous modes. My personal understanding is that the FC channel of our board is normal, but the BC channel is abnormal. Because in the synchronous mode, the CLK of 935 comes from BC, and in the asynchronous mode , 935'clk is generated by itself. What are the possible reasons for this problem? Our ti935 is powered separately without POC. The AC capacitance of dout + terminal is 100nF, and the AC capacitance of dout - terminal is 47nF,work in coax.

Thanks!

  • 0
    TI__Mastermind 29770 points

    Hello,

    What are the MODE settings of the paired UB935 and UB954 devices?

    It is possible for the devices to LOCK and transfer data if the devices are set to the same Forward Channel rate, but you cannot send an I2C command from the UB954 to the UB935 if the Back Channel rates are different.

    The UB935 can be set to CSI-2 Synchronous or Non-Synchronous mode through the strap resistors on the MODE pin, but the UB954 can only be set to CSI-2 Synchronous Mode using the default strap resistors on the MODE pin. In order to set the UB954 to CSI-2 Non-Synchronous Mode, you need to also set register 0x58[2:0] = 010.

    Best,

    Justin Phan

  • 0 in reply to Justin Phan
    Prodigy 60 points

    Thanks for your reply！

    UB935 is Non-Synchronous mode,and set register 0x05=0x0b;

    UB954 is CSI-2 mode.

    Today,i set UB954 register 0x58[2:0] = 010,and i still can not send an I2C command from the UB954 to the UB935.

    here is register setting:

    0x60,0x4c,0x12,0x0808//set 954 port1

    0x60,0x6d,0x7c,0x0808//set 954 CSI-mode,coax

    0x60,0x58,0x5a,0x0808//set 954 bc non-synchronous mode,10Mhz

    0x60,0x5c,0xfe,0x0808//set 935 iic addr 0xfe

    0x60,0x33,0x03,0x0808//en 954 csi

    0x60,0x20,0x10,0x0808//en rx port 1

    0xfe,0x05,0x0b,0x0808//set 953 internal clk 52Mhz

    0xfe,0x03,0x5b,0x0808//set 953 with non-synchronous mode

    0xfe,0xb0,0x00,0x0808//set color bar 1080p 30fps

    0xfe,0xb1,0x01,0x0808

    0xfe,0xb2,0x01,0x0808

    0xfe,0xb1,0x02,0x0808

    0xfe,0xb2,0x33,0x0808

    0xfe,0xb1,0x03,0x0808

    0xfe,0xb2,0x1e,0x0808

    0xfe,0xb1,0x04,0x0808

    0xfe,0xb2,0x0f,0x0808

    0xfe,0xb1,0x05,0x0808

    0xfe,0xb2,0x00,0x0808

    0xfe,0xb1,0x06,0x0808

    0xfe,0xb2,0x01,0x0808

    0xfe,0xb1,0x07,0x0808

    0xfe,0xb2,0xe0,0x0808

    0xfe,0xb1,0x08,0x0808

    0xfe,0xb2,0x04,0x0808

    0xfe,0xb1,0x09,0x0808

    0xfe,0xb2,0x38,0x0808

    0xfe,0xb1,0x0a,0x0808

    0xfe,0xb2,0x04,0x0808

    0xfe,0xb1,0x0b,0x0808

    0xfe,0xb2,0x65,0x0808

    0xfe,0xb1,0x0c,0x0808

    0xfe,0xb2,0x0b,0x0808

    Use the same setting,another 935 board (from someone else's) work ok.My 935 board only  use iic to set registers to work ok.and only non-synchronous mode is ok,synchronous mode is NG.

  • 0 in reply to ni ni
    TI__Mastermind 29770 points

    Hello,

    ni ni said:
    UB935 is Non-Synchronous mode,and set register 0x05=0x0b;

    Do you mean register 0x03 on the UB935 reads 0x0B? I am assuming that the UB935 device is strapped to Non-Synchronous Internal Clock Mode and that the UB954 is strapped to CSI-2 Non-Synchronous Mode. The register dump shows that register 0x58[2:0] = 010 on the UB954 and that the UB935 is connected to RX Port 1 on the UB954. Is my understanding correct?

    If both the the UB935/UB954 devices are strapped to Synchronous mode, then they should be able to LOCK after the devices power-up. 

    And the original question is on why the following scenarios happen in the 935/954 pairing:

    1. Non-Synchronous Mode has video output, but no Back Channel
    2. Synchronous Mode has no LOCK and no video 

    If the UB935 board is swapped with another UB935 board, then the issues disappear. The video transfer is fine in both synchronous & asynchronous mode and back channel communication is possible. If so, it seems that the issue lies in the UB935 board that you are using.

    What is the difference between your UB935 board, which has issues, and the other person's UB935 board, which has no issues?

    Are their schematics and layouts the same?

    Best,

    Justin Phan