Sony Ericsson W890 Troubleshooting Manual page 85

Functional blocks of the Digital Baseband Controller
Keypad
The keypad interface block supports up to 30 keys with 65 columns and 6 rows and operates
in
both scan and idle mode. The keypad scan is performed by software. Any transition in the
state of the column inputs is written directly to the register. The keypad interface
differentiates between single key presses, simultaneous presses of any keys with a function
key, and any key releases. The period between successive scans is programmable over the
range 5 ms to 80 ms, in 5 ms steps. During scan mode, the keypad generates an interrupt
whenever a valid keypad state change occurs (including a release of any pressed keys). The
scan function is disabled during system power-up. The keypad is able to detect at least four
simultaneous key presses. Not all combinations are supported.
FUNCTIONAL OVERVIEW Technical Description
RF System Control
The access subsystem of the digital baseband controller controls the overall radio system. In
both EDGE/GSM/GPRS and WCDMA air interface mode, the digital baseband controller
controls the radio system through a 3-wire serial bus. The digital baseband controller also
manages PA band control and the antenna switch mechanism in the front end module. The 26
MHz VCXO clock residing in the GSM/GPRS/EDGE transceiver is turned on only when required.
The digital baseband controller initiates turning on of the clock. The GSM/GPRS/EDGE RF
system requires control, which is temperature dependent. The temperature within the RF
system is estimated by a voltage measurement performed by the analog baseband controller
N2000 (Vera).
Control flow of the RF system.
Radio Part
Antenna
The mobile system antenna interface connects the Wideband Code Division Multiple
Access (WCDMA) and Global System for Mobile Communication (GSM) input/output to
the antenna of the Mobile Phone. It is a bi-directional RF interface containing signals in the
range 800 MHz to 2.2 GHz. The mobile system antenna interface is the interface between the
Mobile Phone Radio Frequency (RF) input/output and the mobile system antenna. The
interface handles the GSM 850, EGSM 900, GSM 1800, GSM 1900 and WCDMA Band I, RF
inputs/outputs.
Mobile System Antenna Interface:
SEMC Troubleshooting Manual
W890
1217-3942 rev. 1 85 (119)