[linux-dvb] Pinnacle PCTV Sat HDTV Pro USB (PCTV452e)

Manu Abraham abraham.manu at gmail.com
Thu Oct 25 05:30:23 CEST 2007


garlicdevel at ntlworld.com wrote:
>> Are you sure you have changed line 405 in pctv452e.c from
>>         { STB0899_I2CRPT        , 0x5e }, // 0x2c
>> to
>>         { STB0899_I2CRPT        , 0x58 },
>> as register 0xf12a is STB0899_I2CRPT and 0x5c should not appear there.
> ? (this is not included in my posted patch)
> ? 
> ? 
> ? Dominik
> 
> The windows driver seems to set the initial value to 5c when dumping all registers across initially (on device plug in)
> it then seems to change things later on for tuning purposes

This value comes in from a resistor pullup with regards to the STB0899 to avoid 
ringing on the remote I2C bus.This happens to be very much device specific, in 
fact i haven't seen no two devices having the same value. The default value 
(0x5c) is calculated with a resistance of 3kE and 47pF on Pin16 of the STB0899

Large a value will "dampen" the signal, too small a value will cause "ringing". In 
the case of the KNC1 card i was able to calculate it out since the vendor was 
helpful (Eventhough i had done this manually the hard way even before they 
could get back)

Well, the STB0899 has too many fine strings to be finely tuned for a specific device.
This is similar to other demods, but due to the larger number of registers, there are
even more of those "fine threads".

Manu




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