78M6612-IMSLASHFSLASHP datasheet(24/111 Pages) TERIDIAN

24 / 111 page

78M6612 Data Sheet

DS_6612_001

Rev. 1.2

1.4.5

Instruction Set

All instructions of the generic 8051 microcontroller are supported. A complete list of the instruction set

and of the associated op-codes is contained in the Teridian 78M6612 Firmware Developer’s Manual.

1.4.6

UARTs

The 78M6612 includes a UART (UART0) that can be programmed to communicate with a variety of

external devices. A second UART (UART1) is connected to the optical port, as described in Section

1.5.6 Optical Interface.

The UARTs are dedicated 2-wire serial interfaces, which can communicate with an external device at up

to 38,400 bits/s. The operation of each pin is as follows:

•

UART RX: Serial input data are applied at this pin. Conforming to RS-232 standard, the bytes are

input LSB first.

•

UART TX: This pin is used to output the serial data. The bytes are output LSB first.

The 78M6612 has several UART-related registers for the control and buffering of serial data.

The serial buffers consist of sets of two separate registers (one set for each UART), a transmit buffer (S0BUF,

S1BUF) and a receive buffer (R0BUF, R1BUF). W riting data to the transmit buffer starts the transmission by the

associated UART. Received data are available by reading from the receive buffer. Both UARTs can simultaneously

transmit and receive data.

WDCON[7]

Table 11

selects whether timer 1 or the internal baud rate generator is used.

All UART transfers are pro-

grammable for parity enable, parity, 2 stop bits/1 stop bit and XON/XOFF options for variable

communication baud rates from 300 to 38,400 bps.

shows how the baud rates are calculated.

Table 12 shows the selectable UART operation modes.

Table 11: Baud Rate Generation

Using Timer 1

(WDCON[7]

Using Internal Baud Rate Generator

(

= 0)

WDCON[7]

UART 0

= 1)

SMOD * f

CKMPU

/ (384 * (256-TH1))

SMOD * f

CKMPU /(64 * (2

UART 1

-S0REL))

N/A

fCKMPU/(32 * (2

10-S1REL))

S0REL and S1REL are 10-bit values derived by combining bits from the respective timer reload registers.

SMOD is the SMOD bit in the SFR PCON. TH1

Table 12: UART Modes

is the high byte of timer 1.

UART 0

UART 1

Mode 0

N/A

Start bit, 8 data bits, parity, stop bit,

variable baud rate (internal baud rate

generator).

Mode 1

Start bit, 8 data bits, stop bit, variable

baud rate (internal baud rate generator

or timer 1).

Start bit, 8 data bits, stop bit, variable

baud rate (internal baud rate

generator).

Mode 2

Start bit, 8 data bits, parity, stop bit,

fixed baud rate 1/32 or 1/64 of f

N/A

CKMPU.

Mode 3

Start bit, 8 data bits, parity, stop bit,

variable baud rate (internal baud rate

generator or timer 1).

N/A

78M6612-IM/F/P Datasheet(PDF) 24 Page - Teridian Semiconductor Corporation

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