Atmel AT90S8515-4 Pin Descriptions, VCC, GND, Port A (PA7..PA0), Port B (PB7..PB0), Port C (PC7..PC0), Port D (PD7..PD0)

one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.

The AT90S8515 provides the following features: 8K bytes of In-System Programmable Flash, 512 bytes EEPROM, 512 bytes SRAM, 32 general-purpose I/O lines, 32 general- purpose working registers, flexible timer/counters with compare modes, internal and external interrupts, a programmable serial UART, programmable Watchdog Timer with internal oscillator, an SPI serial port and two software-selectable power-saving modes. The Idle Mode stops the CPU while allowing the SRAM, timer/counters, SPI port and interrupt system to continue functioning. The Power-down mode saves the register contents but freezes the oscillator, disabling all other chip functions until the next external interrupt or hardware reset.

The device is manufactured using Atmel’s high-density nonvolatile memory technology. The On-chip In-System Programmable Flash allows the program memory to be reprogrammed In-System through an SPI serial interface or by a conventional nonvolatile memory programmer. By combining an enhanced RISC 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT90S8515 is a powerful microcontroller that provides a highly flexible and cost-effective solution to many embedded control applications.

The AT90S8515 AVR is supported with a full suite of program and system development tools including: C compilers, macro assemblers, program debugger/simulators, in-circuit emulators and evaluation kits.

Pin Descriptions

VCC	Supply voltage.
GND	Ground.
Port A (PA7..PA0)	Port A is an 8-bit bi-directional I/O port. Port pins can provide internal pull-up resistors
	(selected for each bit). The Port A output buffers can sink 20 mA and can drive LED dis-
	plays directly. When pins PA0 to PA7 are used as inputs and are externally pulled low,
	they will source current if the internal pull-up resistors are activated. The Port A pins are
	tri-stated when a reset condition becomes active, even if the clock is not active.
	Port A serves as multiplexed address/data input/output when using external SRAM.
Port B (PB7..PB0)	Port B is an 8-bit bi-directional I/O port with internal pull-up resistors. The Port B output
	buffers can sink 20 mA. As inputs, Port B pins that are externally pulled low will source
	current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset
	condition becomes active, even if the clock is not active.
	Port B also serves the functions of various special features of the AT90S8515 as listed
	on page 66.
Port C (PC7..PC0)	Port C is an 8-bit bi-directional I/O port with internal pull-up resistors. The Port C output
	buffers can sink 20 mA. As inputs, Port C pins that are externally pulled low will source
	current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset
	condition becomes active, even if the clock is not active.
	Port C also serves as address output when using external SRAM.
Port D (PD7..PD0)	Port D is an 8-bit bi-directional I/O port with internal pull-up resistors. The Port D output
	buffers can sink 20 mA. As inputs, Port D pins that are externally pulled low will source

4 AT90S8515

0841GS–09/01