On Thu, 23 Oct 2008 10:46:29 -0700, David Brownell wrote:
> On Thursday 23 October 2008, Jean Delvare wrote:
> >
> > > For SPI, everything is MSB first ... else insist (spi->mode & SPI_LSB_FIRST)
> > > is true. ?Please strike the comment implying it might not be MSB first.
> >
> > Except that the LM70 transmits the LSB first, so it seems valuable to
> > underline that the TMP121 behaves differently.
>
> If true, then this driver has a bug ... it should require
> SPI_LSB_FIRST as well as SPI_3WIRE in spi->mode, for lm70.
>
> But no, I checked the data sheet and it shows MSB first.
> See the table in section 1.5.2 (MSB = D15) and the figures
> in section 2 (D15 first).
>
>
> See what confusion comes from implying things which are
> contrary-to-fact? :)
I didn't assume anything, I simply read the code:
+ switch (p_lm70->chip) {
+ case LM70_CHIP_LM70:
+ raw = (rxbuf[1] << 8) + rxbuf[0];
+ val = ((int)raw/32) * 250;
+ break;
+
+ case LM70_CHIP_TMP121:
+ raw = (rxbuf[0] << 8) + rxbuf[1];
+ val = (raw / 8) * 625 / 10;
+ break;
+ }
Does it look to you like both chips expect the same byte order? Me not.
--
Jean Delvare
