Intel 87C196CB, 8XC196NT Chapter Ports, Port 0 and Eport, C196CB Input/Output Ports, P0PIN

CHAPTER 5

I/O PORTS

5.1PORT 0 AND EPORT

The I/O ports of the 87C196CB are functionally identically to those of the 8XC196NT. However, the 87C196CB implements all eight pins of port 0, and the 100-pin 87C196CB also implements all eight pins of the EPORT. The associated registers have been modified to include bits corre- sponding to the upper nibble of the ports. Table 5-1 provides an overview of the 8XC196CB’s I/O ports. Figure 5-1 illustrates the port 0 pin state register, and Figures 5-2 through 5-5 illustrate the EPORT registers.

Table 5-1. 87C196CB Input/Output Ports

Port		Bits	Type	Direction	Associated Peripheral(s)
Port 0	8		Standard	Input-only	A/D converter
Port 1	8		Standard	Bidirectional	EPA and timers
Port 2	8		Standard	Bidirectional	SIO, interrupts, bus control, clock gen.
Port 3	8		Memory-mapped	Bidirectional	Address/data bus
Port 4	8		Memory-mapped	Bidirectional	Address/data bus
Port 5	8		Memory-mapped	Bidirectional	Bus control, slave port
Port 6	8		Standard	Bidirectional	EPA, SSIO
EPORT	4	(84-pin CB)	Memory mapped	Bidirectional	Extended address lines
	8	(100-pin CB)
P0_PIN					Address:	1FDAH
					Reset State:	XXH

Each bit of the port 0 pin input (P0_PIN) register reflects the current state of the corresponding pin, regardless of the pin configuration.

7

PIN7 PIN6 PIN5 PIN4

0

PIN3 PIN2 PIN1 PIN0

Bit	Bit	Function
Number	Mnemonic
7:0	PIN7:0	Port 0 Pin x Input Value
		This bit contains the current state of P0.x.

Figure 5-1. Port x Pin Input (Px_PIN) Register

5-1