
UART Modules
Freescale Semiconductor
31-21
framing error, overrun error, and received break conditions set the respective PE, FE, OE, and RB error
and break flags in the USR
n
at the received character boundary. They are valid only if USR
n
[RXRDY] is
set.
If a break condition is detected (U
n
RXD is low for the entire character including the stop bit), a character
of all 0s loads into the receiver holding register and USR
n
[RB,RXRDY] are set. U
n
RXD must return to a
high condition for at least one-half bit time before a search for the next start bit begins.
The receiver detects the beginning of a break in the middle of a character if the break persists through the
next character time. If the break begins in the middle of a character, receiver places the damaged character
in the Rx FIFO and sets the corresponding USR
n
error bits and USR
n
[RXRDY]. Then, if the break lasts
until the next character time, receiver places an all-zero character into the Rx FIFO and sets
USR
n
[RB,RXRDY].
shows receiver functional timing.
Figure 31-20. Receiver Timing Diagram
31.4.2.3
FIFO
The FIFO is used in the UART’s receive buffer logic. The FIFO consists of three receiver holding registers.
The receive buffer consists of the FIFO and a receiver shift register connected to the U
n
RXD (see
). Data is assembled in the receiver shift register and loaded into the top empty receiver
holding register position of the FIFO. Therefore, data flowing from the receiver to the CPU is
quadruple-buffered.
In addition to the data byte, three status bits—parity error (PE), framing error (FE), and received break
(RB)—are appended to each data character in the FIFO; overrun error (OE) is not appended. By
C1
C2
C4
C6
C7
C8
C3
C5
C6, C7, and C8 is lost
(C2)
Status
Data
(C3)
Status
Data
(C4)
Status
Data
C5 is
lost
Reset by
command
Receiver
Enabled
USRn[RXRDY]
Overrun
internal
module
select
USRn[FFULL]
(C1)
Status
Data
USRn[OE]
Automatically asserted
when ready to receive
Manually asserted first time,
automatically negated if overrun occurs
UOP0[RTS] = 1
1
UMR2n[RXRTS] = 1
UnRXD
UnRTS
1
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...