Having the AD9912 with a SI5351 at 25Mhz/670mV/pp as input for the DDS.
The communication is working ok (I guess) I have a start frequence S4-S1 (0,1,0,0)
so I get the 77,75879Mhz. After a software 1-time run of updating the registers the frequency changes
to +/- 85,560Mhz. Here after doing a FTW programming, but no frequency is changed.
Do I need something to do with S4-S1 after startup? Or do I have my registers not good?
The datasheet is a bit unclear in my vision about this and setting multipliers.
/////////////////////////////////////////////////////
// //
// Power-down & enable //
// Register 0x0010 default 0xC0 or 0xD0 [2] //
// //
/////////////////////////////////////////////////////
uint8_t Powerdown_digital = 0; // bit 0
uint8_t Powerdown_full = 0; // bit 1
uint8_t Not_used_1 = 0; // bit 2
uint8_t Not_used_2 = 0; // bit 3
uint8_t Powerdown_sysclock_pll = 0; // bit 4*
uint8_t Enable_output_doubler = 0; // bit 5*
uint8_t Enable_CMOS = 0; // bit 6*
uint8_t Powerdown_HSTL = 1; // bit 7
/////////////////////////////////////////////////////
// //
// Register 0x0012 default 0x00 [3] //
// //
/////////////////////////////////////////////////////
uint8_t Reset_DDS = 0; // bit 0
/////////////////////////////////////////////////////
// //
// Power-down & reset //
// Register 0x0013 default 0x00 [4] //
// //
/////////////////////////////////////////////////////
uint8_t Not_used_3 = 0; // bit 0
uint8_t Reset_sdivider = 0; // bit 1
uint8_t Not_used_4 = 0; // bit 2
uint8_t Reset_sdivider2 = 0; // bit 3
uint8_t Not_used_5 = 0; // bit 4
uint8_t Not_used_6 = 0; // bit 5
uint8_t Not_used_7 = 0; // bit 6
uint8_t Powerdown_fund_DDS = 0; // bit 7
/////////////////////////////////////////////////////
// //
// System clock N-divider //
// Register 0x0020 default 0x12 [5] //
// 25Mhz = 20 //
/////////////////////////////////////////////////////
uint8_t N_divider0 = 0; // bit 0*
uint8_t N_divider1 = 0; // bit 1*
uint8_t N_divider2 = 1; // bit 2*
uint8_t N_divider3 = 0; // bit 3*
uint8_t N_divider4 = 1; // bit 4*
uint8_t Not_used_8 = 0; // bit 5
uint8_t Not_used_9 = 0; // bit 6
uint8_t Not_used_10 = 0; // bit 7
/////////////////////////////////////////////////////
// //
// PLL parameters //
// Register 0x0022 default 0x04 [6] //
// //
/////////////////////////////////////////////////////
uint8_t Charge_pump1 = 0; // bit 0*
uint8_t Charge_pump2 = 0; // bit 1*
uint8_t VCO_range = 1; // bit 2
uint8_t Reference_2x = 0; // bit 3*
uint8_t Not_used_11 = 0; // bit 4
uint8_t Not_used_12 = 0; // bit 5
uint8_t Not_used_13 = 0; // bit 6
uint8_t VCO_autorange = 0; // bit 7
