Motorola Internal Use
3
V2288 – Circuit Description
11)
The
RX SPI
signal is made up of
BDR
(Base band Data Receive),
BFSR
(Base band
Frame Synch Receive) and
BCLKR
(Base band Clock Receive, fed from MAGIC
Pins G8, G9 and F7
respectively.
12)
The
Whitecap U800
receives these signals on
Pins A3, D4 and B4,
within the
Whitecap the signal is digitally processed. Baud rate reduced, Error correction bits
removed, etc…
13)
The digital signal is now being fed down the
DI_AUD_SPI
bus to the
GCAP II
U900
, internally, the digital signal is converted to analogue and distributed to the
correct outputs
14)
For Earpiece, from GCAP II
Pins H6 and H7
to speaker pads
J502
and
J503
15)
The Alert is generated within the Whitecap, given the appropriate data from the
incoming signal, SMS, call etc… and is fed to the alert pads
J510
and
J511
. This
signal is supported by the signal
ALRT_VCC
, which is generated from B+ through
Q903
.
16)
For the headset only the
SPKR-
signal is used and feeds the
Stereo Audio IC U1500
,
Pin 12
, and is fed out on
Pin 1
, the exact operation of which can be found in the
Level 3 Block diagram IC description. The output is then fed out on
HEADSET_L
to
the
Headset Jack socket J504.
*NB There is no stereo headset operation for voice
calls.
RF:
Transmit
1)
There are 2 Mic inputs, firstly from the
Xcvr mic J900
, where the analogue input is
fed to the
GCAP II U900
Pin J2
2)
Secondly the analogue voice can be fed from the Aux Mic attached to the headset and
will be routed from
connection 1
of the
headset jack J504
, through to GCAP II,
Pin
H3
.
3)
Within the GCAP II the analogue audio will be converted to digital and clocked out
onto the
DI_AUD
SPI bus to the
Whitecap U800
.
4)
It is within the Whitecap that all information about the transmission burst is
formulated i.e. The timing of the burst / The channel to transmit on / The error
correction protocol / In which frame the information will be carried to the base
station, etc, etc…
5)
All this information is then added to the digitised audio and is transferred to the
MAGIC U200
along a TX SPI bus. The bus is made up of
BCLKX
(Base band Clock
Transmit)
Pin B2
and
BDX
(Base band Data Transmit)
Pin B6
. The timing for this
data is already decided for the transmission burst, and therefore a frame synch is not
required.
6)
The SPI comes into the MAGIC at
Pin G7
(
BCLKX
) and
Pin J2
(
BDX
)
7)
The operation of the MAGIC is very complex and with respect to the transmit path,
intergrates the functions of the Modem and its function of GMSK (Gaussian
Minimum Shift Keying) and also the functions of the TIC (Translational Integrated
Circuit).
