Holtek BC68F2130 Manual page 106

• RF_SX2 Register – RF Fractional-N Synthesizer Control Register 2
Bit 7
Name DK7
R/W R/W
POR 0
Bit 7~0 DK7~DK0: Low byte of 20-bit fractional of dividend for MMD
Set an initial value to implement XO=16MHz and TX band=433.92MHz.
• RF_SX3 Register – RF Fractional-N Synthesizer Control Register 3
Bit 7
Name DK15
R/W R/W
POR 1
Bit 7~0 DK15~DK8: Middle byte of 20-bit fractional of dividend for MMD
Set an initial value to implement XO=16MHz and TX band=433.92MHz.
• RF_SX4 Register – RF Fractional-N Synthesizer Control Register 4
Bit 7
Name —
R/W —
POR —
Bit 7~4 Unimplemented, read as "0"
Bit 3~0 DK19~DK16: High byte of 20-bit fractional of dividend for MMD
Set an initial value to implement XO=16MHz and TX band=433.92MHz.
RF Channel Setup Description (VCO operating frequency: 1.7~1.9GHz, 2.5GHz)
The XODIV2 bit and the RF_OD1 register must be configured according to the following two rules:
• Whether the the VCO operating frequency is in the specified range.
• The calculated DN and DK values are within the available range of RF_SX1~RF_SX4 registers.
The following are five frequency configuration examples (if Crystal=XO=16MHz):
(1) 315MHz
XODIV2=0, RF_OD1=08H
VCO frequency=TX Frequency×8=315MHz×8=2520MHz
XO×(DN+DK/2
(DN+DK/2 )=78.75 → DN[6:0]=4EH=78, DK[19:0]=C0000H=786432
20
Note: The VCO_SWHB bit should be set to "1" by the user program for switching the VCO to
the 2.5GHz band when the TX frequency is 315MHz.
(2) 433MHz
XODIV2=0, RF_OD1=04H
VCO frequency=TX Frequency×4=433MHz×4=1732MHz
XO×(DN+DK/2
(DN+DK/2 )=54.125 → DN[6:0]=36H=54, DK[19:0]=20000H=131072
20
Rev. 1.50
BC68F2130/BC68F2140/BC68F2150
Sub-1GHz RF Transmitter Flash MCU with OCDS
6 5 4
DK6 DK5 DK4
R/W R/W R/W
0 0 0
6 5 4
DK14 DK13 DK12
R/W R/W R/W
1 0 1
6 5 4
— — —
— — —
— — —
) =16MHz×(DN+DK/2 )=VCO frequency/2=2520MHz/2=1260MHz
20 20
)=16MHz×(DN+DK/2 )=VCO frequency/2=1732MHz/2=866MHz
20 20
106
3 2 1
DK3 DK2 DK1
R/W R/W R/W
1 0 1
3 2 1
DK11 DK10 DK9
R/W R/W R/W
0 1 1
3 2 1
DK19 DK18 DK17
R/W R/W R/W
0 0 1
January, 22, 2021
0
DK0
R/W
0
0
DK8
R/W
1
0
DK16
R/W
1