MSP430F5342: Using MSP430 any GPIO in as an Open Drain Output Signal

The MSP430 pins don't provide "true" open-drain, but you can get some of the effects by setting the relevant PxOUT pin to =0 and wiggling the corresponding PxDIR bit. This gives you drive-low/float-high behavior, which is maybe(?) enough for what you want to do.

Hi Bruce,

Sorry for not giving you clear architecture of my design. Below is my design architecture. I have used a open drain level translator to convert the MSP's normal GPIO signal to a open drain signal. Kindly request you to verify my design.

I have connected a GPIO pin of MSP430F5342IRGZR to a SoC's reset input pin via a level translator with P/N TXS0108EQPWRQ1 (With internal pull-up resistors on A and B sides). To the SoC side of the level translator, I have a connected a pull-up resistor. To the MSP side of the level translator I have not connected any pull-up resistors. Refer the below image of my circuit and block diagram of the level translator.

I'm not a EE so I'm not really qualified to verify an electrical design, but I'm pretty sure a GPIO pin can drive low against a 40kOhm pullup.

Hi Bruce,

Okay Bruce. Much thanks for your answers. I'll verify my design @ level translator logic forum. And for additional clarifications, do you know which circuit (Open drain or push-pull) is implemented for GPIO functionality of MSP430 inside each pin?

Hi,

I agree with Bruce's comment. The MSP430 has no open drain IOs. 

Best regards,

Cash Hao

Thanks Bruce for your clarifications and support!

Thanks Cash for your confirmations!