CY8C54 CYPRESS [Cypress Semiconductor], CY8C54 Datasheet - Page 26

• Manufacturer Part Number: CY8C54
• Description: Programmable System-on-Chip (PSoC)
• Manufacturer: CYPRESS [Cypress Semiconductor]

6.3.1.2 Other Reset Sources
6.4 I/O System and Routing
PSoC I/Os are extremely flexible. Every GPIO has analog and
digital I/O capability. All I/Os have a large number of drive modes,
which are set at POR. PSoC also provides up to four individual
I/O voltage domains through the Vddio pins.
There are two types of I/O pins on every device; those with USB
provide a third type. Both General Purpose I/O (GPIO) and
Special I/O (SIO) provide similar digital functionality. The primary
differences are their analog capability and drive strength.
Devices that include USB also provide two USBIO pins that
support specific USB functionality as well as limited GPIO
capability.
All I/O pins are available for use as digital inputs and outputs for
both the CPU and digital peripherals. In addition, all I/O pins can
generate an interrupt. The flexible and advanced capabilities of
the PSoC I/O, combined with any signal to any pin routability,
greatly simplify circuit design and board layout. All GPIO pins can
Document Number: 001-55036 Rev. *A
XRES - External Reset
CY8C54 has either a single GPIO pin that is configured as an
external reset or a dedicated XRES pin. Either the dedicated
XRES pin or the GPIO pin, if configured, holds the part in reset
while held active (low). The response to an XRES is the same
as to an IPOR reset.
The external reset is active low. It includes an internal pull up
resistor. XRES is active during sleep and hibernate modes.
SRES - Software Reset
A reset can be commanded under program control by setting
a bit in the software reset register. This is done either directly
by the program or indirectly by DMA access. The response to
a SRES is the same as after an IPOR reset.
Another register bit exists to disable this function.
WRES - Watchdog Timer Reset
The watchdog reset detects when the software program is no
longer being executed correctly. To indicate to the watchdog
timer that it is running correctly, the program must periodically
reset the timer. If the timer is not reset before a user-specified
amount of time, then a reset is generated.
Note IPOR disables the watchdog function. The program must
enable the watchdog function at an appropriate point in the
code by setting a register bit. When this bit is set, it cannot be
cleared again except by an IPOR power on reset event.
PRELIMINARY
be used for analog input, CapSense
while SIO pins are used for voltages in excess of Vdda and for
programmable output voltages.
Features supported by both GPIO and SIO:
Additional features only provided on the GPIO pins:
Additional features only provided on SIO pins:
USBIO features:
User programmable port reset state
Separate I/O supplies and voltages for up to four groups of I/O
Digital peripherals use DSI to connect the pins
Input or output or both for CPU and DMA
Eight drive modes
Every pin can be an interrupt source configured as rising
edge, falling edge or both edges. If required, level sensitive
interrupts are supported through the DSI
Dedicated port interrupt vector for each port
Slew rate controlled digital output drive mode
Access port control and configuration registers on either port
basis or pin basis
Separate port read (PS) and write (DR) data registers to avoid
read modify write errors
Special functionality on a pin by pin basis
LCD segment drive on LCD equipped devices
CapSense on CapSense equipped devices
Analog input and output capability
Continuous 100 µA clamp current capability
Standard drive strength down to 1.71V
Higher drive strength than GPIO
Hot swap capability (5V tolerance at any operating Vdd)
Programmable and regulated high input and output drive
levels down to 1.2V
No analog input or LCD capability
Over voltage tolerance up to 5.5V
SIO can act as a general purpose analog comparator
Full speed USB 2.0 compliant I/O
Highest drive strength for general purpose use
Input, output, or both for CPU and DMA
Input, output, or both for digital peripherals
Digital output (CMOS) drive mode
Each pin can be an interrupt source configured as rising
edge, falling edge, or both edges
PSoC
®
5: CY8C54 Family Data Sheet
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, and LCD segment drive,
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