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Clock and I/O pin to an external peripheral

Question asked by dan on Jul 21, 2015
Hi all,

I have a STM32F103 and a Secure Access Module (SAM) (PCM1.1 by NXP). The SAM needs a clock input and an I/O pin to send and receive data to and from the MCU. In my design, the clock port of SAM is already connected to PD7 GPIO pin in the MCU. My questions are:

1. The GPIO Ppin PD7 offers only USART2_CK when it is remapped. On the other hand, I am not sure that if I remap this pin, the functionality of the other pin in the remapping group will also be affected which I really don't want to be. For instance, the reference manual of STM32F103 says remapping USART2 will turn pins D3-D7 into pins for USART2 channel. Is there any other way to provide clock to SAM without remapping?

2. The SAM needs also an I/O pin which is used for send and receive. Would it be enough to change the mode of the pin to OUT_PP and FLOATING_IN whenever send/receive to/from SAM will be done from MCU, or there is other ways to configure a bidirectional I/O bus or pin?

Thanks for your help,

Dan.

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