CP3UB17G38 NSC [National Semiconductor], CP3UB17G38 Datasheet - Page 107

• Manufacturer Part Number: CP3UB17G38
• Description: CP3UB17 Reprogrammable Connectivity Processor with USB Interface
• Manufacturer: NSC [National Semiconductor]

of the RSFT register are copied into the URBUF register
and the Receive Buffer Full bit (URBF) is set. The URBF bit
is automatically reset when software reads the character
18.2.2
The Attention mode is available for networking this device
with other processors. This mode requires the 9-bit data for-
mat with no parity. The number of start bits and number of
stop bits are programmable. In this mode, two types of 9-bit
characters are sent on the network: address characters
consisting of 8 address bits and a 1 in the ninth bit position
and data characters consisting of 8 data bits and a 0 in the
ninth bit position.
While in Attention mode, the UART receiver monitors the
communication flow but ignores all characters until an ad-
dress character is received. On receiving an address char-
Attention Mode
16
16
1
1
Sample
2
2
Generator/Checker
Figure 26. UART Asynchronous Communication
Error Detection
3
3
Control and
STARTBIT
Parity
DATABIT
4
4
Figure 25. UART Block Diagram
5
5
6
6
7
7
Transmitter
107
Receiver
8
8
System Clock
from the URBUF register. The RSFT register is not software
accessible.
Baud Rate
acter, the contents of the receive shift register are copied to
the receive buffer. The URBF bit is set and an interrupt (if
enabled) is generated. The UATN bit is automatically
cleared, and the UART begins receiving all subsequent
characters. Software must examine the contents of the UR-
BUF register and respond by accepting the subsequent
characters (by leaving the UATN bit reset) or waiting for the
next address character (by setting the UATN bit again).
The operation of the UART transmitter is not affected by the
selection of this mode. The value of the ninth bit to be trans-
mitted is programmed by setting or clearing the UXB9 bit in
Generator
9
9
Sample
Sample
Baud Clock
Baud Clock
10
10
11
11
12
12
Flow Control
13
13
Logic
14
14
15
15
16
16
DATA (LSB)
DS163
DS061
TXD
RTS
CTS
RXD
1
1
www.national.com