When is the Promira Serial Platform push-pull and when is it open collector?

Question from the Customer

I have some hardware questions about the Promira Serial Platform.  I am using two of the GPIO (pins 14 and 15) as DO (data output). Are they both open-collector pins?  Will I need to add pull-up resistors to my test board?

Response from Technical Support:

Thanks for your question!  The pins are dual function and can be either “push-pull” or  “open collector” depending on how they are configured. For your setup, they are push-pull.

 

 Push-Pull transistors  Open-collector output transistors

Push-Pull

Open Collector

Source: Wikipedia

 These are the details about Pin 14 and Pin 15:

Pin 14 can function as either SPI Slave Select/Chip Select 2 or GPIO signal 03.
Pin 15 can function as either SPI Slave Select/Chip Select 1 or GPIO signal 04.

  • When configured as an SPI chip select (CS), they are “push-pull”, driven by the Promira platform.
  • When configured as a GPIO output, they are “push-pull”, driven by the Promira platform.
  • When configured as GPIO input, they are “tri-stated” – they behave as open-collector.  The internal lines of the Promira platform provide 2.2k pull-up resistors – you do not need to add external pull-up resistors.

We hope this answers your question. Additional resources that you may find helpful include the following:

More questions? More ideas? You can also contact us and request a demo that applies to your application, as well as ask questions about the Promira Serial Platform and other Total Phase products.

Request a Demo