Alternate functions and remap question

Posted on May 17, 2011 at 12:40

Hello, I am very new to the STM32 family. I am currently designing my first board to use a

http://www.st.com/mcu/devicedocs-STM32F103R6-110.html

chip. From reading the data sheet, I understand that the 32KB flash chips do not have all the features that the > 32KB chips have.

Here's where I'm getting confused. From the data sheet, I think this chip should have 2 USARTs. When I look at the pin definitions and find, for example, USART1_TX under the ''alternate functions default'' heading, there is a footnote saying that pin function is not available for chips with < 64KB. However I can still find this function under the ''alternate functions remap'' heading.

Is it true that this chip cannot use many features on their default pins, but still has access to these features on their ''remapped'' pins?

Thanks! :)

Posted on May 17, 2011 at 12:40

Hi lv,

You are right, I think too there is a typo in the data-sheet USART1 pins are available in all STM32 flash size configuration, Otherwise the Internal bootloader can not be operational as it uses USART1 RX and TX pins. So the note for USART1_TX and USART1_RX should be (7) and not (6).

This should be escalated to ST for correction. ;-(

Clt,

Asterix.

Posted on May 17, 2011 at 12:40

Thank you very much for your reply, and letting me know I might not be crazy after all. :)

I just assumed that the data sheet was correct, and that only the remap pins were available, not the default ones. If the data sheet is incorrect it would make much more sense. That would also explain why some of the pins have the same foot note twice.

After double checking, I'm sure you're correct. The footnote #6 appears twice several times, and the footnote #7 seems to never be used at all. Whenever footnote 6 appears twice, that peripheral is indeed not available. It makes sense that it's a simple typo.

Thanks again.

Posted on May 17, 2011 at 12:40

Could someone please help me? All I want to know is which pins I can use for USART1 on

http://www.st.com/mcu/devicedocs-STM32F103R6-110.html

. I'm just not 100% sure I understand the data sheet and would like to double check with someone.

Thanks.