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RM0091 documentation error (stm32f0x1/0x2/0x8)

frankmeyer9
Associate II
Posted on November 07, 2014 at 13:03

Can you spot the (copy&paste) error in the following snippet from the stm32f0x1 reference manual ?

If these MCUs are really capable of storing two bits in one, ST should probably file a patent application immediately ...

Is it otherwise safe to assume that bit 29 of USARTx_CR1 is not properly documented ?

worst-forum-software-ever reference-manual-error

6 REPLIES 6
Posted on November 07, 2014 at 13:30

> Can you spot the (copy&paste) error in the following snippet from the stm32f0x1 reference manual ?

No, I see only a white area below the question - probably forum software problem.

Can you please post RM0091 version and page?

Jan

frankmeyer9
Associate II
Posted on November 07, 2014 at 17:43

DocID018940 Rev 6 (latest version available on ST webpage),

page 702, the very first lines, description of USART_CR1, bit 28, ''M1 : word length'';

How can a single bit be ''[10]''...

Such things could happen.

But my sympathies for this forum software are very limited, to express it politely...

zzdz2
Associate II
Posted on November 07, 2014 at 18:15

I would say these are two bits: M0(bit 12) and M1(bit 28).

frankmeyer9
Associate II
Posted on November 08, 2014 at 10:38

You are right.

But then I consider it a design bug.

Why spreading related bits over several words ?

May it be someone had limited foresight when making the first design ?

zzdz2
Associate II
Posted on November 08, 2014 at 11:08

It looks like ''compatibility'' design.

Older STM32s have a single M bit(12). They renamed existing M bit to M0 and added new M1 bit(28).

I agree it's suboptimal but there is some reason behind it.

frankmeyer9
Associate II
Posted on November 08, 2014 at 17:17

It looks like ''compatibility'' design.

 

...

 

I agree it's suboptimal but there is some reason behind it.

 

As I said, IMHO the reason behind is limited foresight when doing the first design.

Actually, foresight is not the right word, since there had been 7, 8 and 9 bit serial protocols around years before the first ARM.

Similiar to the infamous ''A20 gate'' in intel's x86 CPU designs.