LM3S2965 Datasheet, PDF (297/542 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S2965 Microcontroller
■ No interrupts
The first thing to consider when programming the UART is the baud-rate divisor (BRD), since the
UARTIBRD and UARTFBRD registers must be written before the UARTLCRH register. Using the
equation described in “Baud-Rate Generation” on page 293, the BRD can be calculated:
BRD = 20,000,000 / (16 * 115,200) = 10.8507
which means that the DIVINT field of the UARTIBRD register (see page 306) should be set to 10.
The value to be loaded into the UARTFBRD register (see page 307) is calculated by the equation:
UARTFBRD[DIVFRAC] = integer(0.8507 * 64 + 0.5) = 54
With the BRD values in hand, the UART configuration is written to the module in the following order:
1. Disable the UART by clearing the UARTEN bit in the UARTCTL register.
2. Write the integer portion of the BRD to the UARTIBRD register.
3. Write the fractional portion of the BRD to the UARTFBRD register.
4. Write the desired serial parameters to the UARTLCRH register (in this case, a value of
0x0000.0060).
5. Enable the UART by setting the UARTEN bit in the UARTCTL register.
13.4
Register Map
“Register Map” on page 297 lists the UART registers. The offset listed is a hexadecimal increment
to the register’s address, relative to that UART’s base address:
■ UART0: 0x4000.C000
■ UART1: 0x4000.D000
■ UART2: 0x4000.E000
Note: The UART must be disabled (see the UARTEN bit in the UARTCTL register on page 310)
before any of the control registers are reprogrammed. When the UART is disabled during
a TX or RX operation, the current transaction is completed prior to the UART stopping.
Table 13-1. UART Register Map
Offset Name
Type
0x000 UARTDR
RO
0x004 UARTRSR/UARTECR RO
0x004 UARTRSR/UARTECR RO
0x018 UARTFR
RO
0x020 UARTILPR
R/W
0x024 UARTIBRD
R/W
Reset
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0090
0x0000.0000
0x0000.0000
Description
UART Data
UART Receive Status/Error Clear
UART Receive Status/Error Clear
UART Flag
UART IrDA Low-Power Register
UART Integer Baud-Rate Divisor
See
page
299
301
301
303
305
306
June 04, 2007
297
Preliminary