Looks like PD8W was written to drive the BFO with CLK0 from the Si5351 instead of using the Bitx40 analog BFO.
Though that is only activated if this line turns it on:
? ??
#ifdef IF_Offset
My guess is that this never worked.
The PD8W code initializes the possible BFO frequencies in hundredths of a hz with these lines:
volatile uint32_t LSB = 1199850000ULL;
volatile uint32_t USB = 1200150000ULL;The mistake I see is that the crystal filter is not centered on 12.000000mhz, it's more like 11.997000.The value for LSB given above is correct if the VFO is operating down around 5mhz, the BFO is 1500 hz above the crystal filter center.But the value for USB should be more like 11.995500 mhz, at 1500hz below the crystal filter center.
If the VFO is operating up at 19mhz, then we flip them so the BFO for USB is 11.9985 and for LSB is 11.9955 mhz.If confused, read post ? ? /g/BITX20/message/24724Note that I made the discussion easier to follow in post 24724 by assuming the filter is centered on 12.000mhz,?
but it is actually centered on something like 11.997000 mhz.
The filter uses the series resonant mode of the quartz crystals, and that series resonant mode is a few khz lower
in frequency than the parallel resonant mode marked on the the crystal as 12.000 mhz.
The analog bfo uses the crystal in the 12.000 mhz parallel resonant mode, that frequency is brought down a little bit by
adding capacitance.?
The Bitx40+Raduino as shipped does not have the Si5351's CLK0 driving the BFO,
that would require a hardware mod. ?As shipped, only CLK2 of the Si5351 is used, to drive the VFO.
Jerry, KE7ER
On Thu, Jul 27, 2017 at 07:44 pm, Jerry Gaffke wrote:
I don't know anything about this PD8W code.
However, somewhere in the PD8W code it says:
? ??volatile uint32_t USB = 1200150000ULL;
That code you borrowed from Allard is treating the variable USB as a boolean,
so I assume Allard's version of the USB variable should have a value of either zero (false) or 1 (true):
if (USB) // if we are in UPPER side band mode
? ? si5351.set_freq((IF + Dial_freq) * 100ULL, SI5351_CLK2);
? else // if we are in LOWER side band mode
? ? si5351.set_freq((IF - Dial_freq) * 100ULL, SI5351_CLK2);//12-7 = 5
