
S3C94A5/F94A5 MICROCONTROLLER 
vii 
Table of Contents
 (Continued) 
Part II — Hardware Descriptions 
Chapter 7  
Clock Circuit 
Overview.............................................................................................................................................7-1 
System Clock Circuit...................................................................................................................7-1 
CPU Clock Notation.....................................................................................................................7-1 
Main Oscillator Circuits................................................................................................................7-2 
Clock Status During Power-Down Modes.......................................................................................7-3 
System Clock Control Register (CLKCON).....................................................................................7-4 
Stop Control Register (STPCON) ..................................................................................................7-5 
Chapter 8  
RESET and Power-Down
System Reset.....................................................................................................................................8-1 
Overview.....................................................................................................................................8-1 
Power-Down Modes.............................................................................................................................8-2 
Stop Mode..................................................................................................................................8-2 
Idle Mode....................................................................................................................................8-3 
Hardware Reset Values................................................................................................................8-4 
Chapter 9  
I/O Ports
Overview.............................................................................................................................................9-1 
Port Data Registers .....................................................................................................................9-2 
Port 1.........................................................................................................................................9-3 
Port 2.........................................................................................................................................9-7 
Port 3.........................................................................................................................................9-9 
Port 4.........................................................................................................................................9-15 
Port 5.........................................................................................................................................9-19 
Chapter 10  
Basic Timer 
Overview.............................................................................................................................................10-1 
Basic Timer Control Register (BTCON)..........................................................................................10-2 
Basic Timer Function Description..................................................................................................10-3