
S3C94A5/F94A5 
9
I/O PORTS 
9-1
I/O PORTS
OVERVIEW 
The S3C94A5/F94A5 microcontroller has five bit-programmable I/O ports, P1–P5. Port 1 and port 5 are 7-bit ports, 
port 2 and port 3 are 6-bit ports and port 4 is 8-bit ports. This gives a total of 34 I/O pins. Each port can be flexibly 
configured to meet application design requirements. 
 The CPU accesses ports by directly writing or reading port registers. No special I/O instructions are required. All 
ports of the S3C94A5/F94A5 can be configured to input or output mode.  
Table 9-1 gives you a general overview of S3C94A5/F94A5 I/O port functions. 
Table 9-1. S3C94A5 Port Configuration Overview 
Port 
Configuration Options 
1 
1-bit programmable I/O port. 
Schmitt trigger input or push-pull, open-drain output and software assignable pull-ups. 
Alternatively P1 can be used as input for external interrupts INT. 
2 
1-bit programmable I/O port. 
Input or push-pull, open-drain output and software assignable pull-ups. 
Alternatively P2 can be used as AD0–AD5. 
3 
1-bit programmable I/O port. 
Schmitt trigger input or push-pull, open-drain output and software assignable pull-ups. 
Alternatively P3 can be used as input for external interrupts INT and can be used as AD6–AD11, 
and can be used as CLO, BUZ, T0OUT, T0CAP, and T0CLK. 
4 
1-bit programmable I/O port. 
Schmitt trigger input or push-pull, open-drain output and software assignable pull-ups. 
Alternatively P4 can be used as AD12–AD14 and can be used as SCK, SI, SO, T2CAP, T1CAP, 
T2OUT, and T1OUT and P4.7 can be used as input for external interrupts INT. 
5 
1-bit programmable I/O port. 
Input or push-pull, open-drain output and software assignable pull-ups. 
Alternatively P5.0 can be used as input for external interrupts INT and can be used as AD15.