[linux-dvb] Re: Airstar2 and VHF

[Patrick Boettcher <patrick.boettcher@desy.de>]

On Sun, 19 Dec 2004, John Dalgliesh wrote:

> On Sat, 18 Dec 2004, Christian Schmitt wrote:
> > Hello,
> >
> > i'm using a Technisat Airstar2 for DVB-T reception. It works quite
> > well, but there is one issue: the driver (skystar2) seems to be unable
> > to tune to VHF frequencies, which makes it impossibel to receive 4
> > channels here in Frankfurt/Germany. I already searched the list
> > archives and found some other people reporting the same problem but so
> > far no working solution. The problem does not occur under windows, so
> > it should work under Linux, too. Since i'm not a programmer, I can not
> > solve the issue myself, but i'll be more than happy to help with
> > fixing/testing. Are there currently any efforts to make it work?
> Yes, I am trying to use one in Australia, where all the channels are 7 MHz
> bandwidth like the German VHF channels - so I have even more reason to
> care :)
>
> I've got a pretty good idea of what to do, but I haven't found any time to
> try it out yet, and since I'm leaving for two weeks holiday tomorrow, it
> doesn't look like I'll get to it this year.
>
> But I'll be sure to post here when I do get it working.
Currently Bjarne Steinsbø and me are working a driver for the b2c2-usb 
devices. For the tests we are using a sky2pc (equipped with stv0299) 
and a air2pc box (equipped with a mt352).

We already did some usb snooping with the air2pc card in windows. Bjarne, 
who has the air2pc box, did a scan in windows for channels and recorded 
the usb traffic.

After letting a script doing some beautification we were able to extract 
the tuning information. I adapted the samsung_tdtc9251dh0_pll_set in 
skystar2.c to values I read from the reverse-engineering. (find a patch 
attached, applies against recent cvs). Please try it and report.

I'm not a signal expert, means I don't know what the regs CONT_1|0 of 
mt352 acutally mean. Maybe it is a complete mistake and it will only 
fit for the usb boxes...

If someone of you is interested in more reverse-engineering data just ask.

Hope this helps,
Patrick.

--
  Mail: patrick.boettcher@desy.de
  WWW:  http://www.wi-bw.tfh-wildau.de/~pboettch/
Index: skystar2.c
===================================================================
RCS file: /cvs/linuxtv/dvb-kernel/linux/drivers/media/dvb/b2c2/skystar2.c,v
retrieving revision 1.60
diff -u -3 -p -r1.60 skystar2.c
--- skystar2.c	19 Dec 2004 18:00:44 -0000	1.60
+++ skystar2.c	19 Dec 2004 23:08:30 -0000
@@ -2358,19 +2358,19 @@ static int samsung_tdtc9251dh0_demod_ini
 int samsung_tdtc9251dh0_pll_set(struct dvb_frontend* fe, struct dvb_frontend_parameters* params, u8* pllbuf)
 {
 	u32 div;
-	unsigned char bs = 0;
+	u8 bs = 0x01, tmp = 0xb4;
 
 	#define IF_FREQUENCYx6 217    /* 6 * 36.16666666667MHz */
 	div = (((params->frequency + 83333) * 3) / 500000) + IF_FREQUENCYx6;
 
-	if (params->frequency >= 48000000 && params->frequency <= 154000000) bs = 0x09;
-	if (params->frequency >= 161000000 && params->frequency <= 439000000) bs = 0x0a;
-	if (params->frequency >= 447000000 && params->frequency <= 863000000) bs = 0x08;
+	if (params->frequency >= 48000000 && params->frequency <= 154000000)  { tmp = 0xb4; bs = 0x09; }
+	if (params->frequency >= 161000000 && params->frequency <= 439000000) { tmp = 0xb4; bs = 0x02; }
+	if (params->frequency >= 447000000 && params->frequency <= 863000000) { tmp = 0xbc; bs = 0x08; }
 
 	pllbuf[0] = 0xc2; // Note: non-linux standard PLL i2c address
 	pllbuf[1] = div >> 8;
    	pllbuf[2] = div & 0xff;
-   	pllbuf[3] = 0xcc;
+   	pllbuf[3] = tmp;
    	pllbuf[4] = bs;
 
 	return 0;