I2C interface problem with OmniVision OV7670

I2C interface problem with OmniVision OV7670

[Darius]

Hi,

OV7670 does not support repeated start.
When sending several messages (read or write) in one transaction, 
repeated start is not accepted by OV7670. OV7670 thinks, that it is next 
clock pulse, not repeated start and second message is not acknowledged.
It is known bug of OV7670 or my i2c adapter driver works not correct?
When sending one byte, everything is ok.
It is interesting, how works OV7670 driver, written by Jonathan Corbet?
Because there are used i2c_smbus_write_byte_data() and 
i2c_smbus_read_byte_data() functions, which means, that in one 
transaction two messages are sent - register address (write) and read data.
For me this does not work, only register address is acknowledged by 
OV7670, and second message (read data) fails.

I want to know, is there possibility to use multi-message transactions 
or not?

BR,
Darius

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Re: I2C interface problem with OmniVision OV7670

[Darius]

btw, I got confirmation from OmniVision - OV7670 does not support 
multiple I2C commands.


> Hi,
> 
> OV7670 does not support repeated start.
> When sending several messages (read or write) in one transaction, 
> repeated start is not accepted by OV7670. OV7670 thinks, that it is next 
> clock pulse, not repeated start and second message is not acknowledged.
> It is known bug of OV7670 or my i2c adapter driver works not correct?
> When sending one byte, everything is ok.
> It is interesting, how works OV7670 driver, written by Jonathan Corbet?
> Because there are used i2c_smbus_write_byte_data() and 
> i2c_smbus_read_byte_data() functions, which means, that in one 
> transaction two messages are sent - register address (write) and read data.
> For me this does not work, only register address is acknowledged by 
> OV7670, and second message (read data) fails.
> 
> I want to know, is there possibility to use multi-message transactions 
> or not?
> 
> BR,
> Darius

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