for attn. of STOne-32 re: usb & can memory

ben2 · ‎2007-07-02

Posted on July 02, 2007 at 18:04

ben2 · ‎2011-05-17

Posted on May 17, 2011 at 12:15

In the USB and CAN thread you stated that

''in the STM32 the USB and the CAN shares the same RAM memory for data reception and transmission. So itâ€™s not possible to run both of these two communications peripherals at the same time.''

I assume, as you are the a moderator for this forum you must know what you are talking about.

However the memory map in the datasheet puts the 2 peripherals at different locations. Whilst I know that this doesn't necessarily mean that they don't share ram, I can find no mention in the PDF that they do. In fact the USB section states that it has 512 bytes of dedicated memory. This, I would take to mean it is not shared by anything else.

I would like to know before I start any development work using this part if in fact you can use both or only one of the CAN & USB.

many thanks

Ben

16-32micros · ‎2011-05-17

Posted on May 17, 2011 at 12:15

Hi Ben_fnr,

I confirm that the USB and the CAN share the same Ram memory area for data transmission and reception. The access to this memory could be exclusive by USB or by CAN (and not both of them at the same time)...

With Best Regards

STOne-32

ben2 · ‎2011-05-17

Posted on May 17, 2011 at 12:15

Thank you.

I could find no mention of this in the datasheet. Perhaps on the next revision it could be made a little clearer or more prominent that both can't be used at the same time.

many thanks

Ben

davidlamb9 · ‎2011-05-17

Posted on May 17, 2011 at 12:15

The USB and CAN share the ''dedicated'' 512byte RAM buffer, and so cannot be used concurrently. However, both peripherals can be used in the same application - just not at the same instant.