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TLV571 Control Registers

Sahil Jain
Prodigy 50 points
Other Parts Discussed in Thread: TLV571

Hi,

The datasheet for the TLV571 states that the control registers are set at power-up, and latched at a rising -WR edge.  Since there are two control registers, am I to assume each of the control registers are set separately, and they are held internally until -WR and -CS are asserted, at which point they are latched?

For example, would the following steps be correct:

1. Set A1:0 = 00, and set D5:0 pins accordingly.

2. Set A1:0 = 01, and set D5:0 pins accordingly.

3. Assert  -WR and -CS to latch both registers internally.

Assuming this is correct, does this mean that the control registers cannot be changed without a reset?

 

Regards,

 

Sahil

  • 0
    TI__Guru**** 176431 points

    Hi Sahil,

    Insert step 3 between steps 1 and 2 - you must 'write' to each register individually.  As long as your D7..D0 lines hold the data you want to load into the configuration register, you can set that first and then toggle /WR while /CS is low.  Usually the /CS is asserted, the data bus is configured, and then the /WR strobe loads the data into the register on the rising edge.

  • 0 in reply to Tom Hendrick
    Prodigy 50 points

    Hi,

    Thanks for your response.  I have one further question regarding the information in the datasheet.

    The datasheet states (for software mode, using internal clock), that conversion begins with a rising edge on /WR.  Since there are two registers to set, and each must be set separately by applying a rising edge on /WR, does this mean that a false conversion will begin when the first register (i.e. CR0) is latched?  And do I need to wait for this to complete before setting the second register (CR1)?

    Regards,

    Sahil

  • 0 in reply to Sahil Jain
    TI__Guru**** 176431 points

    Hi Sahil,

    By default the device is in hardware mode, so it is assuming a pulse on CONVST will start the sample/conversion process.  To avoid a possible false conversion trigger, you could simply write CR1 first, followed by CR0.

  • 0 in reply to Tom Hendrick
    Prodigy 50 points

    Hi,

    Thank you for your help!  I found empirically that I could get around my problem by only writing to CR0 (for my application, CR1 did not need to be changed).  Your explanation explains why I was getting a problem.

    Regards,

    Sahil

  • 0 in reply to Sahil Jain
    TI__Guru**** 176431 points

    Great to hear that you have everything working now!  Let us know if there is anything else we can do yo help.