I think differences between the 2 ARM platforms are at a lower level than
owfs. owfs basically uses the kernel-supplied i2c drivers for DS2482-X
communication. My guess is that one platform is using a dedicated i2c port,
and the other is using bit-banging GPIO support.
Paul Alfille
On Wed, Jun 11, 2014 at 8:36 AM, Michele Marcon <m.mar...@riello-ups.com>
wrote:
> Dear Sirs,
> We have discovered a strange behaviour of 1-wire devices with our two
> platforms.
>
> Platform A: Freescale i.MX27L (ARM926EJ-S rev 4 (v5l)), 64Mb RAM DDR,
> kernel 2.6.19.2 (with custom driver and patches), owfs 2.7p28, busybox
>
> Platform B: Freescale i.MX280 (ARM926EJ-S rev 5 (v5l)), 128Mb RAM DDR2,
> kernel 3.12.1 (with patches for device tree), Debian Wheezy 7.2
>
>
> The 1-wire communication is provided over I2C (with the DS2482S-100).
>
> We have tested 1-wire communication without external power (the power
> comes from the 1-wire bus) and we found that:
>
> 1) the owfs process on platform B uses considerably more CPU usage than on
> platform A (on average 0.3% on platform A against 4% on platform B)
>
> 2) the communication is much less reliable on platform B, and I read
> several bogus values (like: -121°C temperature)
>
> Since platform B is more advanced both in hardware and in software these
> results surprises us. Do you have any explanation?
>
> Thanks for your help,
>
>
>
> Michele Marcon
>
> Centro Ricerche
> RPS SpA
> Viale Europa, 7
> 37045 Legnago VR
> Tel. +39 0442 635811 Fax. +39 0442 635934 - Mobile: +39 335 1233317
> Skype Id: - Voip:
> E-mail: m.mar...@riello-ups.com
> Web: www.riello-ups.com
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