pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 162

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

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Embedded Controller Modules
Interrupt Control Register (UICTRL)
This byte-wide register contains the interrupt enable bits and the interrupt status flags. The register is set to 01
Location: 00 FD24
Type: Varies per bit
4.9.5
Calculating the Baud Rate in Asynchronous Mode
The equation for calculating the baud rate is:
BR = SYS_CLK/(16xNxP)
where:
Assuming a system clock of 5 MHz and a desired baud rate of 9600, the NxP term, according to the equation above, is:
The NxP term is then divided by each pre-scaler factor in Table 21 on page 156 to obtain a value closest to an integer. The
factor for this example is 6.5:
Bit
Name
Reset
4-2
Bit
0
1
5
6
7
BR is the baud rate
SYS_CLK is the system clock
N is the value of the baud rate divisor + 1
P is the pre-scaler divide factor selected by the value in the PSR register
NxP = (5x10
N = 32.552/6.5 = 5.008 (N = 5)
Usage Hints
Type
R/W
R/W
R/W
RO
RO
16
EEI
TBE. The bit is set by the hardware when the USART transfers data from UTBUF register to TSFT
register for transmission. It is automatically cleared on the next write to UTBUF register. The bit is set
on reset.
0: Transmit buffer not empty
1: Transmit buffer empty
RBF. The bit is set by the hardware when the USART has received a complete data frame and
transferred the data from RSFT register to URBUF register. The bit is automatically cleared when
RBUF register is read.
0: Receive buffer not full. New data has not been transferred to RBUF since the last time it was read.
1: Receive buffer full. RBUF contains new data since the last time it was read.
Reserved.
ETI. An interrupt is generated when the TBE flag is set. Read/write bit.
0: Disable transmitter interrupt
1: Enable transmitter interrupt
ERI. An RX interrupt is generated when the RBF flag is set. Read/write bit.
0: Disable receiver interrupt
1: Enable receiver interrupt
ETI. An RX interrupt is generated when the ERR flag is set, indicating that a receive error has
occurred.
0: Disable receive error interrupt
1: Enable receive error interrupt
7
0
6
)/(16x9600) = 32.552
ERI
6
0
(Continued)
ETI
5
0
162
4
0
Description
Reserved
3
0
0
2
RBF
1
0
16
on reset.
TBE
Revision 1.07
0
1