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6/17/03
17-1
Chapter 17
Real-Time Clock
The Real Time Clock (RTC) is an AMBA slave module that connects to the APB. The RTC
can provide a basic alarm function or act as a long-time base counter. This is achieved by
generating an interrupt signal after counting for a programmed number of cycles of an RTC
input. Counting in 1-second intervals is achieved using a 1 Hz clock input to the RTC.
Figure 17-1 shows a block diagram of the RTC.
17.1 RTC Features
The RTC provides the following features:
• AMBA APB interface
• 32-bit up-counter with programmable load
• Programmable 32-bit match Compare Register
• Software-maskable interrupt that is set when the Counter and Compare Registers have
identical values.
Figure 17-1. RTC Block Diagram
LH754xx-24
AMBA
APB
INTERFACE
REGISTER
BLOCK
CONTROL
BLOCK
COUNTER
RTCINTR
CLK1HZ
READ VALUE
LOAD VALUE
ADVANCED
PERIPHERAL
BUS (APB)