PBA 313 01
3. The 13 MHz clock circuitry stabilises and is output to the
CLK_REF pin. POR is activated when four complete cycles
have been delivered to the baseband.
7. To activate the radio and be ready for transmission/
receive, write the value 111110112 = 25110 to the VCO/
DAFC control register and the value 101111112 = 19110 to
the Enable register.
4. The baseband should now initiate the XO-trim register,
Control, Modulation and LPO registers. The XO-trim reg-
ister should be set to the stored calibration value from
the production calibration. The Control and Modulation
register should be set to the recommended values for
normal operation.
8. To enter sleep mode power down the crystal by resetting
SYS_CLK_REQ. Bit 2 in the control register must be set to
enable SYS_CLK_REQ.
Ground
5. The LPO frequency must be adjusted to 3.2 kHz. This is
done by comparing LPO_CLK with a fraction of the system
clock frequency, SYS_CLK. The initial calibration of the
LPO can use a successive approximation algorithm that
adjusts the LPO register value from its mid value (256)
in finer and finer steps until satisfied accuracy has been
achieved. This compensates for oscillator frequency varia-
tions due to process variations of the resistors and capaci-
tors. Thereafter, calibration of the LPO only has to be done
due to temperature and voltage variations by increments or
decrements of the LPO register value.
Ground should be distributed with very low impedance as a
ground plane. Connect all GND connections to the ground
plane. It is critical to have a ground plane underneath the
Bluetooth radio in order to shield the VCO tank from any
electrical noise, see figure 12. The ground vias purpose is
to connect the local ground plane to the main ground layer.
Note: If a local ground plane cannot be directly placed under-
neath the radio, then no routing should be planned under-
neath the radio until a layer can be used as a local ground
plane. The Bluetooth radio will be self shielding and no addi-
tional shields should be necessary for normal operating con-
ditions.
6. The Bluetooth radio and the baseband is now initialized up
to the point that is normally called stand-by mode.
VCC
VCC_IO
VCC
VCC_VCO
VCC_IO VCC
TX_DATA
RX_DATA
VCC_IO
Data
Interface
Bluetooth Radio
PBA 313 01
RS232
UART
RS232
Transceiver
SI_CLK
SI_CMS
SI_CMI
SI_CDO
Serial
Interface
GND
Baseband
ASIC
ADDR
VCC
POR_EXT
TX_ON
or
DATA
Memory
GND
Baseband
functionality
(DSP)
RX_ON
ANT
Input
PHD_OFF
SYNT_ON
Control
CTRL
PCM
PX_ON
SYS_CLK_REQ
VCC
TX_CLK
POR
CODEC
XO_P
XO_N
Output
Control
CRYSTAL
LPO_CLK
SYS_CLK
GND
GND
GND
GND
Figure 11. Typical UART or PCM configuration.
10
EN/LZT 146 65 R3B © Ericsson Microelectronics AB, October 2001
ERICSSON [ ERICSSON ]
