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IMCK I2S Master Clock Output
ISCK I2S Serial Clock I/O
ISDI I2S Serial Data In Input
ISDO I2S Serial Data Out Output
IWS I2S Word Select I/O
JTAG module - JTAG
TCK Test Clock Input
TDI Test Data In Input
TDO Test Data Out Output
TMS Test Mode Select Input
Power Manager - PM
RESET_N Reset Input Low
Pulse Width Modulation Controller - PWMA
PWMA35 - PWMA0 PWMA channel waveforms Output
PWMAOD35 -
PWMAOD0
PWMA channel waveforms, open drain
mode
Output
Not all channels support open
drain mode
System Control Interface - SCIF
GCLK9 - GCLK0 Generic Clock Output Output
GCLK_IN2 - GCLK_IN0 Generic Clock Input Input
RC32OUT RC32K output at startup Output
XIN0 Crystal 0 Input
Analog/
Digital
XIN32 Crystal 32 Input (primary location)
Analog/
Digital
XIN32_2 Crystal 32 Input (secondary location)
Analog/
Digital
XOUT0 Crystal 0 Output Analog
XOUT32 Crystal 32 Output (primary location) Analog
XOUT32_2 Crystal 32 Output (secondary location) Analog
Serial Peripheral Interface - SPI
MISO Master In Slave Out I/O
MOSI Master Out Slave In I/O
NPCS3 - NPCS0 SPI Peripheral Chip Select I/O Low
SCK Clock I/O
Timer/Counter - TC0, TC1
A0 Channel 0 Line A I/O
A1 Channel 1 Line A I/O
A2 Channel 2 Line A I/O
Table 3-7. Signal Descriptions List
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ATUC64/128/256L3/4U
Note: 1. ADCIFB: AD3 does not exist.
B0 Channel 0 Line B I/O
B1 Channel 1 Line B I/O
B2 Channel 2 Line B I/O
CLK0 Channel 0 External Clock Input Input
CLK1 Channel 1 External Clock Input Input
CLK2 Channel 2 External Clock Input Input
Two-wire Interface - TWIMS0, TWIMS1
TWALM SMBus SMBALERT I/O Low
TWCK Two-wire Serial Clock I/O
TWD Two-wire Serial Data I/O
Universal Synchronous Asynchronous Receiver Transmitter - USART0, USART1, USART2, USART3
CLK Clock I/O
CTS Clear To Send Input Low
RTS Request To Send Output Low
RXD Receive Data Input
TXD Transmit Data Output
Table 3-7. Signal Descriptions List
Table 3-8. Signal Description List, Continued
Signal Name Function Type
Active
Level Comments
Power
VDDCORE Core Power Supply / Voltage Regulator Output
Power
Input/Output
1.62V to 1.98V
VDDIO I/O Power Supply Power Input
1.62V to 3.6V. VDDIO should
always be equal to or lower than
VDDIN.
VDDANA Analog Power Supply Power Input 1.62V to 1.98V
ADVREFP Analog Reference Voltage Power Input 1.62V to 1.98V
VDDIN Voltage Regulator Input Power Input 1.62V to 3.6V
(1)
GNDANA Analog Ground Ground
GND Ground Ground
Auxiliary Port - AUX
MCKO Trace Data Output Clock Output
MDO5 - MDO0 Trace Data Output Output
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Note: 1. See Section 6. on page 40
3.4 I/O Line Considerations
3.4.1 JTAG Pins
The JTAG is enabled if TCK is low while the RESET_N pin is released. The TCK, TMS, and TDI
pins have pull-up resistors when JTAG is enabled. The TCK pin always has pull-up enabled dur-
ing reset. The TDO pin is an output, driven at VDDIO, and has no pull-up resistor. The JTAG
pins can be used as GPIO pins and multiplexed with peripherals when the JTAG is disabled.
Please refer to Section 3.2.3 on page 13 for the JTAG port connections.
3.4.2 PA00
Note that PA00 is multiplexed with TCK. PA00 GPIO function must only be used as output in the
application.
3.4.3 RESET_N Pin
The RESET_N pin is a schmitt input and integrates a permanent pull-up resistor to VDDIN. As
the product integrates a power-on reset detector, the RESET_N pin can be left unconnected in
case no reset from the system needs to be applied to the product.
The RESET_N pin is also used for the aWire debug protocol. When the pin is used for debug-
ging, it must not be driven by external circuitry.
3.4.4 TWI Pins PA21/PB04/PB05
When these pins are used for TWI, the pins are open-drain outputs with slew-rate limitation and
inputs with spike filtering. When used as GPIO pins or used for other peripherals, the pins have
the same characteristics as other GPIO pins. Selected pins are also SMBus compliant (refer to
Section on page 10). As required by the SMBus specification, these pins provide no leakage
path to ground when the ATUC64/128/256L3/4U is powered down. This allows other devices on
the SMBus to continue communicating even though the ATUC64/128/256L3/4U is not powered.
After reset a TWI function is selected on these pins instead of the GPIO. Please refer to the
GPIO Module Configuration chapter for details.
MSEO1 - MSEO0 Trace Frame Control Output
EVTI_N Event In Input Low
EVTO_N Event Out Output Low
General Purpose I/O pin
PA22 - PA00 Parallel I/O Controller I/O Port 0 I/O
PB27 - PB00 Parallel I/O Controller I/O Port 1 I/O
Table 3-8. Signal Description List, Continued
Signal Name Function Type
Active
Level Comments

ATUC256L4U-AUT

Mfr. #:
Manufacturer:
Microchip Technology / Atmel
Description:
32-bit Microcontrollers - MCU UC3L-256KB Fl 48QFP 85C Grn
Lifecycle:
New from this manufacturer.
Delivery:
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