LG C3100, Service Manual

Page: 20 / 119

- 19 -
3. TECHNICAL BRIEF
The microcontroller subsystem supports all the GSM terminal software, including the layer 1, 2
and 3 of the GSM protocol stack, the MMI, and applications software such as data services, test
and maintenance. It is tightly associated with on-chip system SRAM and also includes boot
ROM memory with a small dedicated routine to facilitate the initialization of the external Flash
Memory via code download using the on-chip serial interface to the external Flash Memory
interface.
The peripheral subsystem is composed of system peripherals such as interrupt controller, real
time clock, watch dog timer, power management and a timing and control module. It also
includes peripheral interfaces to the terminal functions: keyboard, battery supervision, radio and
display. Both the DSP and the MCU can access the peripheral subsystem via the peripheral bus
(PBUS).
For program and data storage, both the MCU subsystem and the DSP subsystem can access
the on chip system SRAM and external memory such as Flash Memory. The access to the
SRAM module is made through the RAM Bus (RBUS) under the control of the bus arbitration
logic. Similarly, access to the Flash Memory is through the parallel External Bus (EBUS).