AM8530H AMD [Advanced Micro Devices], AM8530H Datasheet - Page 159

• Manufacturer Part Number: AM8530H
• Description: Serial Communications Controller
• Manufacturer: AMD [Advanced Micro Devices]

AMD
WR14 selects the baud-rate generator as the RTxC pin, baud-rate generator disabled,
and internal loopback. The baud-rate generator uses the RTxC pin as the clock source
and is not enabled at this time because the SCC initialization is not complete.
7.2.3.2
WR14 enables the baud-rate generator. Bit 0 (LSB) is changed to a ‘1’ to enable the
baud-rate generator; all other bits must maintain the value selected during initialization.
WR3 enables the receiver. Bit 0 (LSB) is changed to a ‘1’ to enable the receiver; all other
bits must maintain the value selected during initialization.
WR5 enables the transmitter. Bit 3 is changed to a ‘1’ to enable the transmitter; all other
bits must maintain the value selected during initialization.
7.2.4
After initialization, and after all enables have been selected, the SCC is ready for commu-
nication. The transmitter buffer and the receive FIFO are empty. The example shown be-
low is coded to transmit and receive characters.
7–10
SCC Operating Mode Enables
Transmit and Receive Routines
Table 7–5. Time Constants for Common Baud Rates
For 2.4576 MHz Clock, X16 Clock Mode
Figure 7–3. Transmit and Receive Routine
;Transmit a character
TXCHAR:INPUT
;Receive a character
RXCHAR:INPUT
buffer
38400
19200
Baud
9600
4800
2400
1200
Rate
600
300
150
TEST
JZ
OUTPUT CHAR
RET
TEST
JZ
INPUT
RET
Dec
126
254
510
14
30
62
RRO
BIT2
TXCHAR;Loop if not empty
RRO
BIT 0 ;Test Receive
RXCHAR;Loop if not full
CHAR
0
2
6
Divider
;Read RRO
;Test transmit
;Output character to
;Return
;Read RRO
;Input character
;Return
buffer empty
data port
from data port
000EH
001EH
003EH
007EH
00FEH
01FEH
0000H
0002H
0006H
Hex
SCC Application Notes