[linux-dvb] STB0899 I2C bus bit rate and Skystar HD ?

Konstantin Dimitrov kosio.dimitrov at gmail.com
Thu Oct 18 08:34:47 CEST 2007


hello All,

the only place that i can find where I2C bus bit rate is set for the
budget-ci driver is in:

http://jusst.de/hg/multiproto/file/096a44e6732a/linux/drivers/media/dvb/ttpci/budget-core.c

line 506:

saa7146_i2c_adapter_prepare(dev, &budget->i2c_adap,
SAA7146_I2C_BUS_BIT_RATE_120);

with that setting i got 16 locks out of 20 tries on Astra 19.2E, 11538V

when i change "SAA7146_I2C_BUS_BIT_RATE_120" to
"SAA7146_I2C_BUS_BIT_RATE_240", i.e. decrease the I2C bus bit rate
then i got only 3 locks out of 20 tries on the same transponder

when i change "SAA7146_I2C_BUS_BIT_RATE_120" to
"SAA7146_I2C_BUS_BIT_RATE_80", i.e. increase the the I2C bus bit rate
then i got 0 locks out of 20 tries on the same transponder

as far as i know current I2C ICs can work at any I2C bus bit rate up
to 400kHz and

SAA7146_I2C_BUS_BIT_RATE_80 ~= 400 kHz
SAA7146_I2C_BUS_BIT_RATE_120 ~= 275 kHz
SAA7146_I2C_BUS_BIT_RATE_240 ~= 135 kHz

so why STB0899 can't lock at any of these I2C bus bit rates ?

thanks!

best wishes,
konstantin



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