FabiaTech FB2701, Руководство пользователя

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Serial Ports
The ACEs (Asynchronous Communication Elements ACE1 to ACE2) are used to convert
parallel data to a serial format on the transmit side and convert serial data to parallel
on the receiver side. The serial format, in order of transmission and reception, is a start
bit, followed by five to eight data bits, a parity bit (if programmed) and one, one and
half (five-bit format only) or two stop bits. The ACEs are capable of handling divisors of
1 to 65535, and produce a 16x clock for driving the internal transmitter logic.
Provisions are also included to use this 16x clock to drive the receiver logic. Also
included in the ACE a completed MODEM control capability, and a processor
interrupt system that may be software tailored to the computing time required to
handle the communications link.
The following table is a summary of each ACE accessible register
DLAB Port Address Register
Receiver buffer (read) 0 Base + 0
Transmitter holding register (write)
0 Base + 1 Interrupt enable
X Base + 2 Interrupt identification (read only)
X Base + 3 Line control
X Base + 4 MODEM control
X Base + 5 Line status
X Base + 6 MODEM status
X Base + 7 Scratched register
1 Base + 0 Divisor latch (least significant byte)
1 Base + 1 Divisor latch (most significant byte)
‰
Receiver Buffer Register (RBR)
Bit 0-7: Received data byte (Read Only)
‰
Transmitter Holding Register (THR)
Bit 0-7: Transmitter holding data byte (Write Only)
‰
Interrupt Enable Register (IER)
Bit 0: Enable Received Data Available Interrupt (ERBFI)
Bit 1: Enable Transmitter Holding Empty Interrupt (ETBEI)