Octagon 5266, Справочное руководство

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Chapter 4: Serial ports
Description
The 5266 has two serial ports, COM1 and COM2. COM1 is a dedicated 8-wire RS–
232C. COM2 can be 8-wire RS–232C, or 4-wire RS–422 or RS–485. COM1 and
COM2 are accessed at the 20-pin connector at J4.
These serial ports interface to serial device. All ports support 5-, 6-, 7-, or 8-bit
word lengths, 1, 1.5, or 2 stop bits, and baud rates up to 115K.
The serial ports have the following specifications:
16C550/16C750 compatible
64-byte FIFO buffers
IEC 1000, level 3, ESD protection
— Contact discharge ±6 kV
— Air–gap discharge ±8 kV
Backdrive protection
Up to 115K baud operation
Mating receptacles
Use a VTC–20F or VTC–20M cable to connect the 20-pin COM ports to external
serial equipment. The P2 and P3 connectors on these cables are DB–9 female
(VTC–20F) or DB–9 male (VTC–20M) connectors which plug directly into a 9-pin
serial cable. Figure 4–1 (following page) shows serial devices connected to the 5266.
Figure 4–2 shows a null modem adapter connected to the COM1 port of a VTC–
20F. A null modem adapter is required when connecting a serial console.
Baud rate divisor registers
The DUART is clocked at 48 MHz; therefore, the baud rate divisor registers must
be programmed using the following equation: 48,000,000 / (16 * desired baud) =
baud rate divisor. Table 4–1 shows the baud rate divisor for standard baud rates.
Table 4–1 Baud rate divisors
Baud Rate Baud Rate Divisor Baud Rate Baud Rate Divisor
110 6a88h 9600 0138h
150 4c20h 19K 009ch
300 2710h 28K 066bh
600 1388h 38K 004ch
1200 09c4h 56K 0035h
2400 04e2h 115K 001ah
4800 0271h
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