STM32L0x Boot0

[felix2]

Posted on April 15, 2016 at 13:45

Fellows

on some STM32L0 (STM32L011x3/4 TSSOP2) Boot0 is also  PB9 on others (STM32L031x4/6 TSSOP2) only Boot0.

Is this not allways the same for a STM32 familiy like STM32L0x?

Is that correct? I think on we need as much as possible Pins on the small cases. Therefore it should be a must to havae also a second function on the Boot0 pin.

Cheers

Felix

#stm32l0 #boot0

[Tesla DeLorean]

Posted on April 15, 2016 at 19:00

Well I suspect that would just complicate testing and recovery.

If is possible to have small packages with higher pin counts.

[Walid FTITI_O]

Posted on April 15, 2016 at 20:55

Hi bonjour.felix,

This is due to the package size which is small. For example, You can find in STM32F4xx devices that boot1 is shared with PB2.

-Hannibal-

[Tesla DeLorean]

Posted on April 15, 2016 at 21:16

No, I think the question being asked is why can't BOOT[0] be a GPIO pin too

[re.wolff9]

Posted on April 16, 2016 at 11:15

The first chips were ''many pin'' packages, so it was not necessary to be really careful with the number of pins. Later, smaller packages were added and you see that as time progresses you get more and more options to use the ''special'' pins as GPIOs too if you know what you're doing. 

However, Suppose your application uses the SWD pins, and you've set the option register to ''boot from flash''. So now you've got trouble if you need to update the firmware. If your design is good there will still be a way, but without the option of the boot mode, things are even more restricted. 

I understand that it ''feels'' wrong to have to get a 32 pin package when a 20pin will ALLMOST fit. 

[felix2]

Posted on April 16, 2016 at 11:43

I am not happy with your answer...

TSSOP20: STM32L011x3/4 has PIN1 BOOT0 / PB9 (DocID027973 Rev 3 35/114)

TSSOP20: STM32L041x4/6 has PIN1 BOOT0 (DocID027301 Rev 3 36/112)

So, same package size (TSSOP20), same family (STM32L0) but differenrt implementaition.

Why? Or is one of the data sheet not correct?

Regards

Felix

[felix2]

Posted on April 16, 2016 at 11:47

Exact, that is what I want to know.