119
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
UARTs
The FPSLIC features two full duplex (separate receive and transmit registers) Universal Asyn-
chronous Receiver and Transmitter (UART). The main features are:
•
Baud-rate Generator Generates any Baud-rate
•
High Baud-rates at Low XTAL Frequencies
•
8 or 9 Bits Data
•
Noise Filtering
•
Overrun Detection
•
Framing Error Detection
•
False Start Bit Detection
•
Three Separate Interrupts on TX Complete, TX Data Register Empty and RX Complete
•
Multi-processor Communication Mode
•
Double Speed UART Mode
Data Transmission
A block schematic of the UART transmitter is shown in Figure 64. The two UARTs are identical
and the functionality is described in general for the two UARTs.
Figure 64.
UART Transmitter
Note:
1. n = 0, 1
PE0/
PE2
U2Xn
10(11)-BIT TX
SHIFT REGISTER
PIN CONTROL
LOGIC
UART CONTROL AND
STATUS REGISTER
(UCSRnA)
UART CONTROL AND
STATUS REGISTER
(UCSRnB)
CONTROL LOGIC
BAUD RATE
GENERATOR
TXCn
IRQ
UDREn
IRQ
DATA BUS
RXCIEn
TXCIEn
UDRIEn
TXCn
UDREn
RXENn
TXENn
CHR9n
RXB8n
TXB8n
RXCn
TXCn
UDREn
FEn
MPCMPn
ORn
IDLE
BAUD
STORE UDRn
SHIFT ENABLE
DATA BUS
BAUD x 16
/16
UART I/O DATA
REGISTER (UDRn)
XTAL
TXDn