About one i2c failure issue after system reset

About one i2c failure issue after system reset

[Jason Hui]

Hi, Ben, Jean,

I have one issue about the i2c failure: there will be on-going i2c
transfer while system get reset.
At the time when the reset happens, the slave may pull the SDA to
LOW.After reset, the i2c master may reset, but
the slave may still pull the SDA to LOW since there is no reset pin
for the slave device to do i2c reset, thus
result in the further i2c access failure forever unless we completely
power off the system by pulling out
the battery.

I know we have the shutdown member function, but as I know there is
very less i2c master has implemented this
function correctly. I think we need take seriously about this issue,
do you have any comments? Thanks,


Jason Liu

Re: About one i2c failure issue after system reset

[Rajeev kumar]

Hello Jason

On 11/21/2011 1:05 PM, Jason Hui wrote:
> Hi, Ben, Jean,
>
> I have one issue about the i2c failure: there will be on-going i2c
> transfer while system get reset.
> At the time when the reset happens, the slave may pull the SDA to
> LOW.After reset, the i2c master may reset, but
> the slave may still pull the SDA to LOW since there is no reset pin
> for the slave device to do i2c reset, thus
> result in the further i2c access failure forever unless we completely
> power off the system by pulling out
> the battery.
>
This is not the only solution for this. Master can accomplishes error 
recovery by clocking Clock until Data is high and then issuing a Start 
followed by a Stop.

Best Regards
Rajeev
...

> I know we have the shutdown member function, but as I know there is
> very less i2c master has implemented this
> function correctly. I think we need take seriously about this issue,
> do you have any comments? Thanks,
>
>
> Jason Liu
> --
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Re: About one i2c failure issue after system reset

[Michael Lawnick]

Am 21.11.2011 08:35, schrieb Jason Hui:
> Hi, Ben, Jean,
> 
> I have one issue about the i2c failure: there will be on-going i2c
> transfer while system get reset.
> At the time when the reset happens, the slave may pull the SDA to
> LOW.After reset, the i2c master may reset, but
> the slave may still pull the SDA to LOW since there is no reset pin
> for the slave device to do i2c reset, thus
> result in the further i2c access failure forever unless we completely
> power off the system by pulling out
> the battery.
> 

This is a common failure scenario and should be solved by your adapter
driver automatically by issuing 9 clock cycles on detection.
-- 
KR
Michael