AM8530H AMD [Advanced Micro Devices], AM8530H Datasheet - Page 161

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

AMD
7.3.3.1
WR9 resets SCC to a known state by writing a C0 hex. This command, Force Hardware
Reset, is identical to a hardware reset. It will reset both channels.
WR4 selects asynchronous mode, x16 mode, 2 stop bits and no parity. The x16 mode
means that the clock rate is 16 times the data rate.
WR2 is the interrupt vector of the SCC. Even though a vector is not placed in the bus in
this mode the vector including status is read from RR2. By writing 00H to this register the
status read will be the only bits set in RR2.
WR3 selects 8 bits per character and does not enable the receiver. The 8 bits per charac-
ter allows 8 bits to be assembled from the data stream. The receiver is not enabled at this
time because the SCC is not completely initialized.
WR5 selects 8 bits per character and does not enable the transmitter. The 8 bits per char-
acter allows 8 bits to be sent as data with the least significant bit first. The transmitter is
not enabled at this time because the SCC is not completely initialized.
WR9 selects that there are no interrupts enabled. This will inhibit the SCC from request-
ing an interrupt from the CPU.
WR10 selects NRZ encoding. This selects NRZ coding that is to be used on the transmit-
ter and the receiver.
WR11 selects the RTxC pin to TTL clock, the transmit and receive clocks source as the
baud-rate generator and the TRxC pin as a baud-rate generator output.
7–12
Table 7–6. SCC Initialization Order for Interrupt Driven Asynchronous Mode
Enable Interrupts
Register
Enables
SCC Operating Modes Programming
WR10
WR11
WR12
WR13
WR14
WR14
WR9
WR4
WR2
WR3
WR5
WR9
WR3
WR5
WR1
WR9
Value
C0H
4CH
C0H
C1H
00H
60H
00H
00H
56H
06H
00H
10H
11H
68H
12H
08H
Comments
Force Hardware Reset
x 16 clock, 2 stop bits, no parity
Interrupt Vector 00
Rx 8 bits, Rx disabled
Tx 8 bits, DTR, RTS, Tx off
Int Disabled
NRZ
Tx & Rx = BRG out, TRxC = BRG out
Time constant = 6
Time constant high = 0
BRG in = RTxC, BRG of, loopback
BRG enable
Rx enable
Tx enable
Rx Int on all char and Tx Int enables
MIE
SCC Application Notes