Sony Ericsson W995 Troubleshooting Manual page 94

Application Subsystem
The Application subsystem contains functionality related to functions such as MMI,
graphics, audio and memory media. The control CPU is an ARM926 with three external
memory interfaces, one shared with the Access subsystem and two dedicated for the
Application subsystem. The Application subsystem contains several blocks. The main
communication between the blocks is done through the Advanced High performance bus
(AHB) matrix, which is a set of control buses connecting the different parts. A block called
Syscon is responsible for distributing clocks and resets to all parts of the Application
subsystem. This block is under SW control. The Application subsystem is connected to the
Shared EMIF that is used for code execution or data storage. In addition, a dedicated EMIF
that support SDRAM or static memory like NOR, PsRAM or NAND are also available. The
Application EMIF is a general interface for communication with, for example external
SDRAM, PSRAM, NOR flash, NAND flash and companion chips
Application Subsystem of the Digital Baseband Controller:
FUNCTIONAL OVERVIEW Technical Description
The 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.
SEMC Troubleshooting Manual
W995
1230-1858 rev. 1 94 (125)