
GT-96100A Advanced Communication Controller
Revision 1.0
365
NOTE: When CD* is deasserted during frame reception UART behavior is different for multidrop and normal
modes. In normal mode the UART hunts for an IDLE character (hunting starts when CD* is asserted
again) before receiving valid start bit. In this mode, transmitting from a GT-96100A model to another
should be with the ’P’ bit in the buffer descriptor set. In multidrop mode, the UART receiver hunts for a
start bit as soon as CD* is asserted again.
14.7.4 UART Stop Bit Reception and Framing Error
The UART receiver always expects to find a stop bit at the end of a character. If no stop bit is detected, the Fram-
ing Error (FE) bit is set in the receive descriptor. After a framing error, the reception process is controlled by the
RZS and UM bits in the UART MPCRx. The various options are summarized in the table bellow.
13:12
CL
Character Length
00 - 5 data bits
01 - 6 data bits
10 - 7 data bits
11 - 8 data bits
01
14
SBL
Stop Bit Length
0 - One stop bit
1 - Two stop bits
0
15
FLC
Flow Control
0 - Normal Mode. The CTSM bit in the MMCRx determines the CTS* pin
behavior.
1 - Asynchronous Mode. When CTS* is negative, transmission stops at the
end of the current character. When CTS* is asserted again the transmission
starts from the place it stopped. No CTS* lost is reported. Line is IDLE
(MARK) during CTS* deassertion period.
0
31:16
Reserved
0
Table 347: UART Stop Bit Reception and Framing Error
UM
RZS
O peration
Break
Recognitio n
00
0
Go to hunt after missing a stop bit. The receiver is enabled after
receiving a new IDLE char.
Single Break
00
1
The receiver tries to synchronize itself. The missing stop bit is
considered as the following start bit and the reception process
continues.
Two Break Sequence
Table 346: MPSCx Protocol Configuration Register (MPCRx) for UART Mode, Offset: 0x000A08,
0x008A08, 0x010A08, 0x018A08, 0x020A08, 0x028A08, 0x030A08, 0x038A08
(where x is the port number 0 to 7)
(Continued)
Bits
Field
Name
F unctio n
In itial
Value