About TX EMPTY of SCI for F28035

Yang Meng-Chu

Prodigy 150 points

Other Parts Discussed in Thread: TMS320F28035

I have confused about TXEMPTY of SCI for the TMS320F28035.

The flag defined as below:

The figure refers to TMS320x2802x, 2803x Piccolo Serial Communications Interface (SCI).

The figure can observe this flag set high after the stop bit.

But the results are not the same with our’s experiment result.

The experiment use 38400 baud rate, so the frame length is 1/38400*10.

Ch2: Singnal pull low represent TXEMPTY flag set high

Ch3: TX signal

But the flag set high before the stop bit. Please let me know if have any answer, thanks.

over 14 years ago

0 Daniel Chang over 14 years ago

TI__Expert 4120 points

I am not sure what the exact timings are but perhaps TX EMPTY goes high as soon as the actual data is completed and does not include the Stop bit since the Stop bit is automatically generated by the SCI and not stored in the registers.

Also, if you were to extend the timing diagram such that the second Stop bit is as large as the first one, you will see that the TX EMPTY signal goes high before the end of the Stop bit. I would not use the timing diagram as an exact guide but more of a reference example.

0 Yang Meng-Chu over 14 years ago in reply to Daniel Chang

Prodigy 150 points

thanks for your reply, have any flah or method can detect end of TX signal include STOP bit?

0 Daniel Chang over 14 years ago in reply to Yang Meng-Chu

TI__Expert 4120 points

You could try determining it based on the TX EMPTY signal timing. I will ask our SCI expert if he has any suggestions.

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About TX EMPTY of SCI for F28035