Re: I2C block reads with i2c-viapro: testers wanted

[Krzysztof Halasa <khc@pm.waw.pl>]

Hi,

Jean Delvare <khali@linux-fr.org> writes:

> Partly right. Actually, most SMBus controllers work the following way:
> you program a number of registers (typically SMBus transaction type,
> target chip address, target register address or command, and the data to
> send in the case of a write transaction),

So, with one transaction, can I write an arbitrary number of bytes to
the device, and then, in the same transaction, can I read one (or no,
or with some controllers, more than one) byte(s) back?

>> But wait, even then does the controller really know anything about
>> I^2C commands? How would it differentiate between, say, 8-bit and
>> 16-bit reads? Or is it just an 8-bit EEPROM bus?
>
> No, it is still physically a 2-wire serial bus.

Sure, I rather meant "a bus _for_ I^2C EEPROMs which use 8-bit (+3)
addressing".

> The limitation is due to
> the fast that the SMBus controller knows of a limited number of
> transactions, such as Send Byte, Read Byte, Read Word etc. If the SMBus
> controller doesn't know of the SMBus command you want to use (in my
> case, I2C block read), then there is no way to do it, because we have no
> direct control over the serial line.

Interesting. Still, that limits it to 8-bit-addressable EEPROMs.

Are such things documented somewhere on the net (some datasheet maybe)?
-- 
Krzysztof Halasa
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