
Programmable Four-Channel Communications Controller
—
CD2481
Datasheet
145
9.3
Bit Rate and Clock Option Registers
9.3.1
Receive Baud Rate Generator Registers
9.3.1.1
Receive Baud Rate Period Register (RBPR)
This register contains the preload value for the receive baud rate counter. When using an internal
clock option or an n-times external clock, the preload value in conjunction with the receiver clock
source chosen, determines the receive baud rate. If a 1
×
external clock is used, a value of 01h must
be loaded in the RBPR.
9.3.1.2
Receive Clock Option Register (RCOR)
This register is used to select the DPLL mode, and the desired clock source for the receive baud
rate generator.
Bit 7
TLVal
–
Transmit line value
This bit reflects the logical value of the transmit data pin. It is a read-only bit; writing
to this bit has no effect.
Bit 6
Reserved
–
must be zero
.
Bit 5
DPLL enable
1 = DPLL is enabled
0 = DPLL is disabled
Bits 4:3
DPLL mode selects the type of data encoding used.
Register Name: RBPR
Register Description: Receive Bit-Rate Period Register
Default Value: x
’
81
Access: Byte Read/Write
Intel Hex Address: x
’
C9
Motorola Hex Address: x
’
CB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Receive Bit Rate Period (Divisor)
Register Name: RCOR
Register Description: Receive Clock Option Register
Default Value: x
’
00
Access: Byte Read/Write
Intel Hex Address: x
’
CA
Motorola Hex Address: x
’
C8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TLVal
0
DpllEn
Dpllmd1
Dpllmd0
ClkSel2
ClkSel1
ClkSel0