Operation

Divider =

66MHz

= 215(decimal) = 00D6(hexadecimal)

[----------------------------32 x 9600]

therefore UBG1n = 0x00 and UBG2n = 0xD6.

23.5.1.2.2External Clock

An external source clock (DTINn) can be used as is or divided by 16.

Externalclockfrequency

Baudrate = ----------------------------------------------------------------

[16or1][16bitdivider]

23.5.2 Transmitter and Receiver Operating Modes

Figure 23-19is a functional block diagram of the transmitter and receiver showing the command and operating registers, which are described generally in the following sections and described in detail in Section 23.3, “Register Descriptions.”

UART

Transmit Buffer

(UTBn)

(2 Registers)

UART Receive

Buffer (URBn)

(4 Registers)

UARTn

 

 

UART Command Register (UCRn)

W

 

UART Mode Register 1 (UMR1n)

R/W

 

UART Mode Register 2 (UMR2n)

R/W

 

UART Status Register (USRn)

R

 

Transmitter Holding Register

W

External

Interface

Transmitter Shift Register

 

UTXD

Receiver Holding Register 1

R

FIFO

 

Receiver Holding Register 2

 

 

Receiver Holding Register 3

 

 

Receiver Shift Register

 

URXD

 

 

Figure 23-19. Transmitter and Receiver Functional Diagram

23.5.2.1Transmitter

The transmitter is enabled through the UART command register (UCRn). When it is ready to accept a character, the UART sets USRn[TxRDY]. The transmitter converts parallel data

23-20

MCF5282 User’s Manual

MOTOROLA

Page 494
Image 494
Motorola MCF5282 Transmitter and Receiver Operating Modes, Therefore UBG1n = 0x00 and UBG2n = 0xD6, External Clock, Fifo