mcf5307cft90b Freescale Semiconductor, Inc, mcf5307cft90b Datasheet - Page 317

• Manufacturer Part Number: mcf5307cft90b
• Description: Mcf5307 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

14.3.3 UART Status Registers (USRn)
The USRn, Figure 14-4, shows status of the transmitter, the receiver, and the FIFO.
Table 14-4 describes USRn fields.
Bits
3–0
Bits
Address
7
6
Reset
Field
R/W
Name
SB
Name
RB
FE
Stop-bit length control. Selects the length of the stop bit appended to the transmitted character.
Stop-bit lengths of 9/16th to 2 bits are programmable for 6–8 bit characters. Lengths of 1 1/16th to 2
bits are programmable for 5-bit characters. In all cases, the receiver checks only for a high condition at
the center of the first stop-bit position, that is, one bit time after the last data bit or after the parity bit, if
parity is enabled. If an external 1x clock is used for the transmitter, clearing bit 3 selects one stop bit
and setting bit 3 selects 2 stop bits for transmission.
RB
7
Received break. The received break circuit detects breaks that originate in the middle of a received
character. However, a break in the middle of a character must persist until the end of the next
detected character time.
0 No break was received.
1 An all-zero character of the programmed length was received without a stop bit. RB is valid only
Framing error.
0 No framing error occurred.
1 No stop bit was detected when the corresponding data character in the FIFO was received. The
0000 1.063
0001 1.125
0010 1.188
0011 1.250
SB
when RxRDY = 1. Only a single FIFO position is occupied when a break is received. Further
entries to the FIFO are inhibited until RxD returns to the high state for at least one-half bit time,
which is equal to two successive edges of the UART clock.
stop-bit check occurs in the middle of the first stop-bit position. FE is valid only when RxRDY = 1.
Table 14-3. UMR2n Field Descriptions (Continued)
5 Bits
Figure 14-4. UART Status Register (USRn)
FE
6
Freescale Semiconductor, Inc.
Table 14-4. USRn Field Descriptions
For More Information On This Product,
6–8 Bits
0.563
0.625
0.688
0.750
Chapter 14. UART Modules
PE
5
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MBAR + 0x1C4 (USR0), 0x204 (USR1)
0100
0101
0110
0111
SB
5 Bits
1.313
1.375
1.438
1.500
OE
4
0000_0000
Read only
Description
Description
6–8 Bits
0.813
0.875
0.938
1.000
TxEMP
3
1000
1001
1010
1011
SB
TxRDY
2
5–8 Bits
1.563
1.625
1.688
1.750
Register Descriptions
FFULL
1100
1101
1110
1111
1
SB
5–8 Bits
1.813
1.875
1.938
2.000
RxRDY
0
14-7