[sdiy] STM32 processor

[Mikko Helin]

Tried Atoll TRUEStudio, work OK, just got to remember to avoid spaces
in path names (so in Winxx don't unzip or create workspaces under "My
Documents").

Btw. Checked the errata for the STM32F4 version used in DISCOVERY kit.
Seems that there are problems when using external converters as master
(=STM32 is slave mode). Don't know how can I ensure that the WS line
is in high level when enabling the I2S in STM initialization (is it
enough to poll some GPIO pin connected to WS, dont' know). I assume
that it is better to avoid running STM as slave (now so good thing
jitterwise).

===
2.3 I2S peripheral limitations
2.3.1 In I2S slave mode, WS level must to be set by the external master
when enabling the I2S
Description
In slave mode the WS signal level is used only to start the
communication. If the I2S (in
slave mode) is enabled while the master is already sending the clock
and the WS signal
level is low (for I2S protocol) or is high (for the LSB or
MSB-justified mode), the slave starts
communicating data immediately. In this case the master and slave will
be desynchronized
throughout the whole communication.
Workaround
The I2S peripheral must be enabled when the external master sets the WS line at:
● High level when the I2S protocol is selected.
● Low level when the LSB or MSB-justified mode is selected.
===

- Mikko

On Thu, Oct 13, 2011 at 1:44 AM, Eric Brombaugh <ebrombaugh1 at cox.net> wrote:
> On 10/12/2011 03:12 PM, KD KD wrote:
>>
>> could one hope write DSP code in C?
>
> You can always write DSP code in C. How well it performs is another story
> entirely. Inferring your DSP intent from C code is a notoriously difficult
> problem for compiler writers, so there are typically two approaches:
>
> 1) Provide libraries of hand-optimized assembly callable from C. That's what
> MCHP does for their dsPIC.
>
> 2) Provide 'intrinsics' - little compiler supported pseudo functions that
> hook into the DSP features of your processor without requiring you to do
> heavy assembly.
>
> Neither of these is particularly intuitive or portable, but they're the only
> way to solve the problem absent artificial intelligence in the compiler. My
> own approach is to hand-code the critical functions and do the rest high
> level.
>
> Eric
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>