TL16C752C: Register Write inability

TS Yang

Genius 4800 points

Part Number: TL16C752C

Hello,

The internal register of TL16C752C can read but not write.

In the datasheet, LCR seems to be able to read and write without restriction, but it can not be written.

Signal timing is more marginal than requirements.

Please check if there are any issues to consider when writing, and please check if there are any problems in the circuit below.

thanks,

over 8 years ago

0 Francisco Javier Zamudio over 8 years ago

TI__Expert 5455 points

Hello TS Yang

I can see that you have a problem with the reset connection. Reset is active high, and you have this pin tied to vcc trough 4.7 K resistor. I recommend you disconnect this resistor and connect like pull down. With this one you can ensure that you device is not in reset state.
You can take a look into our power supply recommendations, in that one we recommend to use extra capacitors as close as possible of Vcc pin of UART.
Before you start to work with the device, I recommend you to apply a reset and then, read register LCR and LSR (the values that they have to have are 1D and 60).

Please, do these changes and let me know your results.

Regards
Francisco

0 TS Yang over 8 years ago in reply to Francisco Javier Zamudio

Genius 4800 points

Hello Francisco,

Reset was overlooked because Active low is common.

We confirmed that it works normally after setting it to Active High.

It is unusual for the Read to be performed even when the reset is applied.

Thank you for your help.

0 Francisco Javier Zamudio over 8 years ago in reply to TS Yang

TI__Expert 5455 points

Hello TS

Great! Let us know if you need something else.

Regards
Francisco

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TL16C752C: Register Write inability