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ADS54J66: Register Addreses 7000h and Above Not Documented in Spec and Do Not Respond on EVM

Chris Raynolds
Prodigy 60 points
Part Number: ADS54J66


Referring to the ADS54J66 specification Section 8.1 Application Information: 8.1.1 Start-Up Sequence, no addresses 7000h and above as referred to in Table 72. Recommended Power-Up Sequence are documented in the specifications register set, either in Table 15. Register Map or in Section 7.6.3 Register Descriptions, and in the lab no write to the 7000h and above range on being read reflects the data written on the ADS54J66EVM. Can one set of SYNC signals, SYNCbAB_P/N or SYNCbCD_P/N, really control all 4 JESD204 channels?

  • 0
    TI__Guru* 91947 points

    Chris,

    When you see 7000h, this is referring to a mode when broadcast writes are disabled and the user must write to both channels of the digital SPI bank. See table 11 of the data sheet. A "0" in bit 20 of a SPI write will set the writes to target CHA & CHB. Setting this bit to a "1" will target writes to CHC & CHD. See an example below of writes to these two locations. Normally broadcast write mode is disabled and all writes go to both channel banks. These is why you do not see to many writes with 700h.

    0x4005 0x01    // 0100/Main Dig page, disable broadcast mode, allows writes to CHAB and CHCD

    0x4004 0x68   // 0100/Main Dig page 
    0x4003 0x00    // 0100/Main Dig page
    0x4002 0x00    // 0100/Main Dig page
    0x4001 0x00    // 0100/Main Dig page
    0x6042 0x01    // 0110/Main Dig page Reg Access 42 Nyquist zone AB
    0x7042 0x01    // 0111/Main Dig page Reg Access 42 Nyquist zone CD
    0x604E 0x80   // 0110/Main Dig page Reg Access 4E Enable Nyquist zone AB
    0x704E 0x80    // 0110/Main Dig page Reg Access 4E Enable Nyquist zone CD

    0x4005 0x00     // 0100/Main Dig page, enable broadcast writes

    SYNCbAB_P/N or SYNCbCD_P/N can be used to control all JESD channels or just CHA/B or CHC/D. By default, after a reset, the part is setup to only use SYNCbAB for all channels. To change this you would have to modify bit 5 of address 0x01 in page 6900h for both channels using the steps shown above.

    Regards,

    Jim