AM8530H AMD [Advanced Micro Devices], AM8530H Datasheet - Page 162

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

SCC Application Notes
WR12 & WR13 select the baud-rate generator time constant. The time constant is deter-
mined by the equation:
In this example, the clock frequency is 2.4576 MHz, the baud rate is 9600, and the clock
mode is 16; the time constant is 6. Converting this time constant to a 16-bit hexadecimal
number, it becomes 0006H. The time constant Low (WR12) is 06H and the time constant
High (WR13) is 00H. The baud rate for this example can be varied for as long as the data
rate is less than
mon baud rates.
WR14 selects the baud rate source as the RTxC pin, baud rate generator disabled, and
internal loopback. The baud-rate generator will use the RTxC pin as the clock source for
the baud-rate generator. The baud-rate generator is not enabled at this time because the
SCC initialization is not complete.
7.3.3.2
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.
7.3.3.3
WR1 enables the Tx and the Rx interrupts. The Rx interrupt is programmed to generate
an interrupt on all received characters or special conditions. This provides an interrupt on
every character received by the SCC. The external/status interrupts are not enabled in
this application.
WR9 sets the master interrupt enable (MIE) bit 3. Setting this bit enables the interrupts
pending to generate and interrupt on the INT pin.
SCC Operating Mode Enables
SCC Operating Mode Interrupts
Time Constant =
1
Table 7–7. Time Constants for Common Baud Rates
/
4
of the PCLK rate. Table 7–7 gives the time constants for other com-
For 2.4576 MHz Clock, X16 Clock Mode
38400
19200
Baud
9600
4800
2400
1200
Rate
600
300
150
2 x Baud Rate x clock mode
Clock Frequency
Dec
126
254
510
14
30
62
0
2
6
Divider
000EH
001EH
003EH
007EH
00FEH
01FEH
0000H
0002H
0006H
Hex
–2
AMD
7–13