AM8530H AMD [Advanced Micro Devices], AM8530H Datasheet - Page 98

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

AMD
5.2.2
The source of the receive clock is controlled by bits D6 and D5 of WR11. The receive
clock may be programmed to come from the RTxC pin, the TRxC pin, the output of the
baud rate generator, or the transmit output of the DPLL.
5.2.3
The source of the transmit clock is controlled by bits D4 and D3 of WR11. The transmit
clock may be programmed to come from the RTxC pin, the TRxC pin, the output of the
baud rate generator, or the transmit output of the DPLL.
Ordinarily the TRxC pin is an input, but it becomes an output if this pin is not selected as
the source for the transmitter or the receiver, and bit D2 of WR11 is set to ‘1’. The selec-
tion of the signal provided on the TRxC output pin is controlled by bits D1 and D0 of
WR11. The TRxC pin may be programmed to provide the output of the crystal oscillator,
the output of the BRG, the receive output of the DPLL or the actual transmit clock. If the
output of the crystal oscillator is selected but the crystal oscillator has not been enabled,
the TRxC pin will be driven High. The option of placing the transmit clock signal on the
TRxC pin, when it is an output, allows access to the transmit output of the DPLL.
5–4
D
7
D
0
0
1
1
6
Receive Clock Source
Transmit Clock Source
D
0
1
0
1
5
Receive Clock = RTxC Pin
Receive Clock = TRxC Pin
Receive Clock = BR Generator Output
Receive Clock = DPLL Output
D
0
0
1
1
4
D
0
1
0
1
3
Transmit Clock = RTxC Pin
Transmit Clock = TRxC Pin
Transmit Clock = BR Generator Output
Transmit Clock = DPLL Output
D
2
WR11—Clock Mode Control
D
0
0
1
1
1
D
0
1
0
1
0
TRxC Out = XTAL Output
TRxC Out = Transmit Clock
TRxC Out = BR Generator Output
TRxC Out = DPLL Output
TRxC O/I
RTxC X TAL/NO X TAL
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