AT91M40400-25C ATMEL Corporation, AT91M40400-25C Datasheet - Page 64

• Manufacturer Part Number: AT91M40400-25C
• Description: 16/32-bit Microcontroller, 2.7V to 3.6V Operating Range
• Manufacturer: ATMEL Corporation

USART: Universal Synchronous/Asynchronous Receiver/Transmitter
The AT91M40400 provides two identical, full-duplex, uni-
versal synchronous/asynchronous receiver/transmitters
that interface to the APB and are connected to the Periph-
eral Data Controller.
The main features are:
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Figure 34. USART Block Diagram
Pin Description
Each USART channel has the following external signals:
Note: After a hardware reset, the USART pins are not
enabled by default (see PIO: Parallel I/O Controller on
page 50). The user must configure the PIO Controller
before enabling the transmitter or receiver.
Programmable Baud Rate Generator
Parity, Framing and Overrun Error Detection
Name
64
RXD
SCK
TXD
USxIRQ
MCKI/8
MCKI
Description
USART Serial clock can be configured as input or output:
SCK is configured as input if an External clock is selected (USCLKS[1] = 1)
SCK is driven as output if the External Clock is disabled (USCLKS[1] = 0) and Clock output is enabled (CLKO = 1)
Transmit Serial Data is an output
Receive Serial Data is an input
ASB
APB
AMBA
AT91M40400
Peripheral Data Controller
Baud Rate Generator
Receiver
Channel
Interrupt Control
Control Logic
Transmitter
Channel
Baud Rate Clock
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If the user selects one of the internal clocks, SCK can be
configured as a PIO.
USART Channel
Line Break Generation and Detection
Automatic Echo, Local Loopback and Remote Loopback
channel modes
Multi-drop Mode: Address Detection and Generation
Interrupt Generation
Two Dedicated Peripheral Data Controller channels
5-, 6-, 7- and 8-bit character length
Transmitter
Receiver
Controller
Parallel
PIO:
I/O
RXD
TXD
SCK