The W65C22 versatile
interface
Interface or interfacing may refer to:
Academic journals
* ''Interface'' (journal), by the Electrochemical Society
* '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics''
* '' Inter ...
adapter (VIA) is an
input/output device for use with the
MOS 65xx series microprocessor family.
Overview
Designed by the
Western Design Center
The Western Design Center (WDC), located in Mesa, Arizona, is a company that develops intellectual property for, and licenses manufacture of, MOS Technology 65xx based microprocessors and microcontrollers. WDC was founded in 1978 by a former ...
, the W65C22 is made in two versions, both of which are rated for 14
megahertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base ...
operation, and available in
DIP-40 or
PLCC-44 packages.
W65C22 Versatile Interface Adapter (VIA)
/ref>
*W65C22N: This device is fully compatible with the NMOS 6522 produced by MOS Technology
MOS Technology, Inc. ("MOS" being short for Metal Oxide Semiconductor), later known as CSG (Commodore Semiconductor Group) and GMT Microelectronics, was a semiconductor design and fabrication company based in Audubon, Pennsylvania. It is ...
and others, and includes current-limiting resistor
A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...
s on its output lines. The W65C22N has an open-drain
Open collector, open drain, open emitter, and open source refer to integrated circuit (IC) output pin configurations that process the IC's internal function through a transistor with an exposed terminal that is internally unconnected (i.e. "open ...
interrupt output (the pin) that is compatible with a wired-OR
A wired logic connection is a logic gate that implements boolean algebra (logic) using only passive components such as diodes and resistors. A wired logic connection can create an AND or an OR gate. Limitations include the inability to create a ...
interrupt circuit. Hence the DIP-40 version is a "drop-in" replacement for the NMOS part.
*W65C22S: This device is fully software– and partially hardware–compatible with the NMOS part. The W65C22S' output is a totem pole
Totem poles () are monumental carvings found in western Canada and the northwestern United States. They are a type of Northwest Coast art, consisting of poles, posts or pillars, carved with symbols or figures. They are usually made from large t ...
configuration, and thus cannot be directly connected to a wired-OR interrupt circuit.
As with the NMOS 6522, the W65C22 includes functions for programmed control of two peripheral ports (ports A and B). Two program–controlled 8-bit bi-directional peripheral I/O ports allow direct interfacing between the microprocessor and selected peripheral units. Each port has input data latching capability. Two programmable data direction registers (A and B) allow selection of data direction (input or output) on an individual I/O line basis.
Also provided are two programmable 16-bit interval timer/counters with latches. Timer 1 may be operated in a one-shot or free-run mode. In either mode, a timer can generate an interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...
when it has counted down to zero. Timer 2 functions as an interval counter or a pulse counter. If operating as an interval counter, timer 2 is driven by the microprocessor's PHI2 clock source. As a pulse counter, timer 2 is triggered by an external pulse source on the chip's line.
Serial data transfers are provided by a serial to parallel/parallel to serial shift register, with bit transfers synchronized with the PHI2 clock. Application versatility is further increased by various control registers, including an interrupt flag register, an interrupt enable register and two Function Control Registers.
Features
* Two 16-bit timer/counters
* Two 8-bit parallel I/O ports, bi-directional, programmable direction and latching
* One synchronous serial I/O port, bi-directional
* TTL compatible I/O
* W65C22N has open-drain interrupt output, W65C22S has push-pull totem-pole interrupt output
* Software compatible with NMOS 6522 devices
* Bus compatible with high-speed W65C02S and W65C816S microprocessors
* Advanced CMOS process technology for low power consumption
* 1.8V to 5V power supply
See also
* W65C02 8-bit microprocessor
* W65C816S 16-bit microprocessor
* Interrupts in 65xx processors
The 65xx family of microprocessors, consisting of the MOS Technology 6502 and its derivatives, the WDC 65C02, WDC 65C802 and WDC 65C816, and CSG 65CE02, all handle interrupts in a similar fashion. There are three hardware interrupt signals comm ...
References
External links
W65C22 Datasheet
dated Sept 13, 2010 from the Western Design Center
The Western Design Center (WDC), located in Mesa, Arizona, is a company that develops intellectual property for, and licenses manufacture of, MOS Technology 65xx based microprocessors and microcontrollers. WDC was founded in 1978 by a former ...
website
{{MOS CPU
Input/output integrated circuits