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TL16C752C: Parity error with no parity setting

cosy toki
Prodigy 10 points
Part Number: TL16C752C


Tool/software:

Nice to meet you.

I am currently developing using the TL16C752C.

I am developing with the communication settings set to no parity.

Sometimes, when I look at the Line Status Register (LSR), a parity error occurs.

Is it okay to ignore this parity error?

Also, why does a parity error occur with a no parity setting?

The settings are as follows.

Crystal used: 19.6608MHz

Baud rate: 2400bps

Data length: 8 bits

Stop bit: 1

No parity

DLL: 0000 0000

DLH: 0000 0010

FCR: 0000 0111

MCR: 0000 0100

LCR: 0000 0011

Thank you in advance for your help.

  • 0
    TI__Guru* 77791 points

    Hi Cosy,

    Just want to double check, what value are you reading from LSR? (Are there any other errors that are flagged?)

    Are you sure the LCR bit 3 is '0'?

    When you read the data, are you able to verify the data is correct when the parity flag is set?

    Also, why did you choose the 752C? Our newer version is the 752D with a fix the the shot stop bit errata that the C family has.

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 10 points

    Hello, Bobby

    Thank you for your reply.
    I have organized the code and checked it again.
    I had confused an overrun error with a parity error.

    Just to confirm, is it correct that when the LCR bit 3 is '0', a parity error will not occur?

    Cosy

  • +1 in reply to cosy toki
    TI__Guru* 77791 points

    Hi Cosy,

    Table 10 should provide the correct flags. 

    If LSR bit 3 =1 then it is a framing error. I asked this because the C version of this family has a errata associated with it which can cause a framing error.

    https://www.ti.com/lit/er/sllz058a/sllz058a.pdf?ts=1752782165219&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTL16C752C

    LSR bit 2 is the parity error (if bit is = 1). or LSR = XX1X XXXX then a parity error has occurred. I don't expect you to see a parity error if you aren't using parity though.

    cosy toki said:
    Just to confirm, is it correct that when the LCR bit 3 is '0', a parity error will not occur?

    0 means no error has occurred for framing issues (this detects if the stop bit is not aligned). 

    -Bobby