Samsung KS57C2308 Manual page 211

KS57C2308/P2308/C2316/P2316 I/O PORTS
10
I/O PORTS
OVERVIEW
The KS57C2308/C2316 has 9 ports. There are total of 8 input pins, 8 output pin and 24 configurable I/O pins, for
a maximum number of 40 pins.
Pin addresses for all ports are mapped to bank 15 of the RAM. The contents of I/O port pin latches can be read,
written, or tested at the corresponding address using bit manipulation instructions.
Port Mode Flags
Port mode flags (PM) are used to configure I/O ports to input or output mode by setting or clearing the
corresponding I/O buffer.
Pull-Up Resistor Mode Register (PUMOD)
The pull-up resistor mode registers (PUMOD) are used to assign internal pull-up resistors by software to specific
ports. When a configurable I/O port pin is used as an output pin, its assigned pull-up resistor is automatically
disabled, even though the pin's pull-up is enabled by a corresponding PUMOD bit setting.
N-Channel Open-Drain Mode Register (PNE)
The n-channel, open-drain, mode register (PNE) is used to configure outputs as n-channel, open-drain outputs or
as push-pull outputs.
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