For what it's worth, I attach here following a snippet of the C++ code I
use to drive the I0CG's AD9951 DDS in the SDR-X receiver. Feel free to
use it as an example for your project.
In the code below, the assumptions are that the DDS is connected to the
parallel port in this way :
DDS DATA D0 (pin 2)
DDS CLOCK D1 (pin 3)
DDS I/O UPD D2 (pin 4)
DDS RESET D3 (pin 5)
the pin numbers above are those of the 25-pin Centronics parallel port
connector. The SM object referred to in the code is a kernel driver that
allows to do direct port I/O under Windows XP. The LED object is just
that, a Led in the GUI. You can ignore that.
73 Alberto I2PHD
-------------------------------------------------------
//----------------------------------------------------------------------\
-----
#define DDS_CLK_HIGH {x=SM->ReadByte(base); x |= 0x02;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_CLK_LOW {x=SM->ReadByte(base); x &= 0xfd;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_DATA_HIGH {x=SM->ReadByte(base); x |= 0x01;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_DATA_LOW {x=SM->ReadByte(base); x &= 0xfe;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_UPDATE_HIGH {x=SM->ReadByte(base); x |= 0x04;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_UPDATE_LOW {x=SM->ReadByte(base); x &= 0xfb;
SM->WriteByte(base, x); Sleep(0);}
#define DDS_RESET_HIGH {x=SM->ReadByte(base); x |= 0x08;
SM->WriteByte(base, x); Sleep(1);}
#define DDS_RESET_LOW {x=SM->ReadByte(base); x &= 0xf7;
SM->WriteByte(base, x); Sleep(1);}
static long two2_32; // actually, this is a class member. I
have placed it here for simplicity
static long double DDSclock; // actually, this is a class member. I
have placed it here for simplicity
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::Initialize(void)
{
char name[256];
// allocate parallel ports, so to keep Windoze away from it...
strcpy(name, "LPT1");
porthandle1 =
CreateFile(name,GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL\
,
NULL);
strcpy(name, "LPT2");
porthandle2 =
CreateFile(name,GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL\
,
NULL);
two2_32 = 1 << 16;
two2_32 *= two2_32;
DDSclock = clockMHz * 1.e6; // clockMHz can be either 400 or 500
InitDDS();
}
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::InitDDS()
{
LED->Value = true;
openLPTport();
DDS_RESET_HIGH
DDS_RESET_LOW
if(clockMHz == 400) // clockMHz is a class member that can be
either 400 or 500 MHz
{
DDSShiftOut(0x01); // address CFR2
DDSShiftOut(0); DDSShiftOut(0); DDSShiftOut(0x27); // set mult.
fac. to 4
} // max pump
current
DDS_UPDATE_HIGH
DDS_UPDATE_LOW
closeLPTport();
SendFreq(LOfreq);
}
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::SendFreq(long freq)
{
byte b;
char s[64];
int clockMHz, base, x, tword;
long double DDSfreq = freq * 4.;;
int mhz = freq/1000000, khz = (freq - mhz*1000000)/1000, hz = freq -
mhz*1000000 - khz*1000;
LED->Value = true;
tword = (int)((DDSfreq / DDSclock) * two2_32 + 0.5);
openLPTport();
DDSShiftOut(0x04); // FTW address
b = (tword >> 24) & 0x000000ff; // MSB
DDSShiftOut(b);
b = (tword >> 16) & 0x000000ff; // MSB - 1
DDSShiftOut(b);
b = (tword >> 8) & 0x000000ff; // MSB - 2
DDSShiftOut(b);
b = tword & 0x000000ff; // MSB - 3 == LSB
DDSShiftOut(b);
DDS_UPDATE_HIGH
DDS_UPDATE_LOW
closeLPTport();
sprintf(s, "%3d,%03.3d.%03.3d", mhz, khz, hz);
LDDSfreq->Caption = s;
LED->Value = false;
}
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::openLPTport(void)
{
bool bl;
base = (lpt == one) ? 0x378 : 0x278;
bl = SM->OpenDriver();
bl &= SM->IsOpen();
if(!bl)
{
MessageBox(NULL, "Errors opening the kernel driver...", "SDR-X",
MB_OK);
Application->Terminate();
return;
}
}
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::closeLPTport(void)
{
SM->CloseDriver();
}
//----------------------------------------------------------------------\
-----
void __fastcall TDLLForm::DDSShiftOut(byte b)
{
for(int k=0; k<8; k++)
{
if(b & (0x80 >> k))
DDS_DATA_HIGH
else
DDS_DATA_LOW
DDS_CLK_HIGH
DDS_CLK_LOW
}
}
//----------------------------------------------------------------------\
-----
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