
IBM39STB0210x
STB0210x Digital Set-Top Box Integrated Controllers
Advance
Architecture and Subsystem Information
Page 12 of 39
STB02_sds_0327.fm.01
March 27, 2000
Additional Interfaces
External Graphics and Video (EGV) Port
External Graphics and Video (EGV) ports provide flexibility for interfacing external graphics and video compo-
nents. When the EGV is used as an output, its signals may be routed to an external graphics device or
DENC. When used as an input, either the internal OSD graphics can be replaced with data from an external
graphics device, or external digital video data (from an analog signal converted to digital via DSMD, for exam-
ple) could replace the internally decoded MPEG video. In the latter case, the external digital video can be
merged/blended with the internal OSD graphics.
Peripheral Subsystem
General Purpose Timer
The General Purpose Timer (GPT) is an on-chip peripheral bus (OPB) function that provides a separate time
base counter and additional system timers beyond those defined in the PPC401B3.
Three Inter-Character (IC) time-out timers are also implemented in this functional unit in the GPT. These tim-
ers receive the count signal inputs from other units they are timing. Each timer is a 10-bit down counter
loaded with a programmable value (TOUT) upon the active edge of the count signal input. Once loaded, the
IC timer counts down TOUT number of TCLK cycles until it reaches zero (that is, when the IC timer has
expired). When a timer expires, it sets its corresponding bit in the IC interrupt status register.
There is a separate time base inside the GPT, distinct from the time base within the PPC401B3. Two event
timers capture unique input events and there are two compare timers with unique outputs. Separately config-
urable and programmable synchronization controls edge detection and output levels. There are two reset
inputs, one for the entire GPT unit, and one for the time base.
OPB
Peripheral Subsystem
Other
Subsystems
GPT / PWM
SmartCard
IIC
16550 Serial Com
Infrared Serial Com
GPIO
Serial Control Port
IBM STB0210x
Modem Interface
PLB0
OPB
Bridge