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Original question:

TL16C752D: initial value of LCR Register

TL16C752D: THR Interrupt

KAEDE KUDO
Expert 2700 points
Part Number: TL16C752D

Hello,

My customer has a question about TL16C752D.

[Q]

My customer replaced TL16C752B to TL16C752D.

They expect the TL16C752D to behave the same as the TL16C752B.
However, even though they write the same settings to the TL16C752D as the TL16C752B, they do not have the expected behavior with the TL16C752D.

They set up the TL16C752D and TL16C752B as follows.

- ADDRESS 001: IER = 0x05
- ADDRESS 010: FCR = 0xC1
- ADDRESS 011: LCR = 0x03
- ADDRESS 100: MCR = 0x08
- ADDRESS 111: SPR =0xFF

Set the following Register when sending data.

- ADDRESS 001: IER = 0x0F

When a transmit interrupt occurs, they expect to get the following behavior:

- ADDRESS 010: IIR = 0x02

However, the above behavior has been observed in the TL16C752B, but not in the TL16C752D.

- TL16C752B: IIR = 0x01 -> 0x02
- TL16C752D: IIR = 0x01


How can I advise the customer to solve this problem?
Thank you for your cooperation.

Best Regards,

Kaede Kudo

  • 0
    TI__Mastermind 49370 points

    Hey Kaede,

    I suggest the customer first check to see if they are actually properly writing to FCR. What you have provided to me does not make sense.

    - ADDRESS 010: FCR = 0xC1

    - ADDRESS 010: IIR = 0x02

    Bits 7 and bit 6 of IIR mirror bit 0 of FCR. in FCR you set the bit 0 to 1 but IIR states that bits 7 and 6 are 0.

    This tells me the device is not being programed correctly. The major difference between the B version and D version of this device is the AFR/EFR register was added. This means you need to make sure that to write to FCR, you need to insure LCR bit 7 =0. This was not a requirement in the B device but D version this requirement is there.

    -Bobby

  • 0 in reply to BOBBY
    Expert 2700 points

    Hello,Bobby

    Thank you for your fast reply!

    I understood your comment.

    I confirm this to the customer.

    Best Regards,

    Kaede Kudo

  • 0 in reply to KAEDE KUDO
    Expert 2700 points

    Hello Bobby,

    My customer solved the problem.
    As you answered, it seems that I improved it by setting LCR bit7 = 0.
    Thank you for your cooperation!

    Best Regards,

    Kaede Kudo