Agere Systems Inc.
189
Data Sheet
July 2001
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
14 IrDA_ACC and UART_ACC
(continued)
For example:
Where BRD is programmed as 0x13 and SM is programmed as 0x9.
There is also an additional choice that reduces the error even more in some cases. If
AL/CO
of the
mode control
register
is set to 1, alternate mode is entered. In this mode, the least significant bit of the sample count is toggled
for every other bit. In alternate mode, for example, if the sample count is set to 23, then the first bit uses a sample
count of 23, the next bit 22, then 23, and so on. Using this mode reduces the error for some baud rate choices.
14.1.4 Extended Characters
The ACC can generate the following two types of special characters in 9-bit mode:
I
A break character.
I
An idle character.
A break
character consists of 11 start bits (zeros) and an idle character consists of 11 stop bits (ones). To use
these extended characters,
ECE
of the
mode control register
is set to 1. To transmit these characters, write a
data value to the transmit FIFO according to Table 168.
Idle characters have no effect on the receiver.
Table 168. Extended Characters
14.2 ACC Registers
Table 169. IrDA_ACC and UART_ACC Communication Controller Register Map
Data Value Range
0x000:0x1FF
0x200
0x20:0x3FE
0x3FF
Resulting Character
Normal 9-bit character.
Break character.
Do not write these values.
Idle character.
Register
IrDA_ACC Address
0xE000 8000
0xE000 8004
0xE000 8008
0xE000 8010
0xE000 8014
0xE000 8018
0xE000 801C
0xE000 8020
0xE000 8040
0xE000 8044
UART_ACC Address
0xE000 9000
0xE000 9004
0xE000 9008
0xE000 9010
0xE000 9014
0xE000 9018
0xE000 901C
NA
0xE000 9040
0xE000 9044
Baud rate register
(see Table 170 on page 190)
.
Baud rate counter register
(see Table 171 on page 190)
.
FIFO status register
(see Table 172 on page 191)
.
Receiver control register
(see Table 173 on page 192)
.
Transmitter control register
(see Table 175 on page 193)
.
Mode control register
(see Table 176 on page 193)
.
Tx/Rx FIFO register
(see Table 177 on page 194)
.
IrDA feature register
(see Table 178 on page 194)
.
ACC interrupt register
(see Table 179 on page 195)
.
ACC interrupt enable register
(see Table 180 on page 196)
.
aud rate =
BRD + 1
)
SM
19
1
+
(
)
)
9
16
)
+
(
(
----------system clock
5.2 KHz =
16
)
+
(
(
----------57.6 MHz