[linux-dvb] [Patch] FMD1216 band updates and control bytes
stoth at hauppauge.com
Tue Nov 29 03:10:32 CET 2005
>> Hm, the data sheet of the FMD2116ME MK3 is - lets say - a problem.
>> One issue is the DVB-T IF frequency. I got told it is 36.125MHz but
>> this can't be right. The tuner can't tune to this frequency, it should
>> be 36.167MHz. Tuning step size definitely is 166.667kHz (4MHz / 24),
>> so this is wrong in your patch. Also all examples in the data sheet
>> have bit 6 of the bandswitch byte set...
> Errors in data sheets seem to be quite common, I only trust
> tested code. Steve, if you can check Philips reference code
> or Hauppauge Windoze driver code, this would be a more
> reliable source for these numbers...
The datasheet dated Sep 8 2005, in a number of places, says the DVB-T IF
is 36.13. In fact, various version of the datasheet say the same thing.
You're telling me it's just plain wrong?
The 166.7 figure comes from the control bite matrix. I guess can be
accounted for by a rounding issue in the sheet. Fair enough.
Bit 6, (P6) is not mentioned anywhere in the datasheet other than using
the Philips example tool. I chose not to set the bit because it wasn't
documented. Tuning clearly works with or without it.
Any comments on the upp/lower freqs of the bands?
>> There generally is a problem with dvb-pll.c: I miss functions to
>> initialize and to "deinitialize" the tuner. This is very important for
>> hybrid analog and digital cards. That's why i have my own versions in
>> saa7134-dvb.c - including FMD1216. This should be changed some time.
> Would should the "initialize" and "deinitialize" functions do?
> I thought the PLL is used by both the analog and digital
> demodulators, so all you do with the PLL when switching
> between analog and digital is writing the new config
> via i2c?
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