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4-8
AT90S8414
Preliminary
Pin Descriptions
VCC
Supply voltage
GND
Ground
Port A (PA7..PA0)
Port A is an 8-bit bidirectional I/O port. Port pins can provide internal pullups (selected for each bit). The Port A output
buffers can sink 20mA and can drive LED displays directly. When pins PA0 to PA7 are used as inputs and are externally
pulled low, they will source current (IIL) if the internal pullups are activated.
Port A serves as Multiplexed Address/Data input/output when using external SRAM.
Port B (PB7..PB0)
Port B is an 8-bit bidirectional I/O pins with internal pullups. The Port B output buffers can sink 20 mA. As inputs, Port
B pins that are externally pulled low will source current (IIL) if the pullups are activated.
Port B also serves the functions of various special features of the AT90S8414 as listed on Page 4-62.
Port C (PC7..PC0)
Port C is an 8-bit bidirectional I/O port with internal pullups. The Port C output buffers can sink 20 mA. As inputs, Port
C pins that are externally pulled low will source current (IIL) if the pullups are activated.
Port C also serves as Address output when using external SRAM.
Port D (PD7..PD0)
Port D is an 8-bit bidirectional I/O port with internal pullups. The Port D output buffers can sink 20 mA. As inputs, Port
D pins that are externally pulled low will source current (IIL) if the pullups are activated.
Port D also serves the functions of various special features of the AT90S8414 as listed on Page 4-70.
RESET
Reset input. A low on this pin for two machine cycles while the oscillator is running resets the device.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier
ICP / VPP
ICP is the input pin for the Timer/Counter1 Input Capture function.
When programming the AT90S8414 in parallel programming mode, the programming voltage, VPP is applied to this pin.
OC1B
OC1B is the output pin for the Timer/Counter1 Output CompareB function