On Wed, 16 Nov 2011 10:20:38 -0800, York Sun wrote:
> On Wed, 2011-11-16 at 19:09 +0100, Jean Delvare wrote:
> > Your thinking is too focused on I2C block reads (or even block read of
> > data over the network or on disk). SMBus block read is something
> > completely different. It's not about reading 200 bytes of data and
> > receiving it in 16-byte chunks (I2C block read works that way, on
> > EEPROMs in particular.) There is no "data length" and "block size" to
> > compare to each other. It's about reading the value of _one_ register
> > and this value happens to be multi-byte. There is typically _no_
> > register pointer increment (automatic or not) involved as can happen
> > with EEPROMs. If an SMBus block read from register N returns 10 bytes,
> > you're not going to read the next 10 bytes from register N+10. There
> > are no "next 10 bytes" to read, and register N+10 is something
> > completely unrelated.
> >
> > And for this reason, it is not possible to mix SMBus block reads with
> > byte reads, as can be done with I2C block reads.
> >
> > Also note that there is a limit of 32 bytes for SMBus block transfers,
> > per SMBus specification. All slaves and masters must comply with it.
> >
> > I hope I managed to clarify the case this time...
>
> You have made it much clear. If block size is fixed and block read
> cannot mix with byte read, shall we do this
>
> if length < block_size
> read block_size
> else {
> while (length) {
> read block_size
> length -= block_size
> }
Which part of
There is no "data length" and "block size" to compare to each other.
did you not understand?
--
Jean Delvare
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