A8351601 View Datasheet(PDF) - AMIC Technology

Part Name

Description

Manufacturer

A8351601

Bar Code Reader

AMIC Technology 

A8351601 Series

Timer/Counter 2 Set-Up

Except for the baud rate generator mode, the values given

for T2C0N do not include the setting of the TR2 bit.

Therefore, bit TR2 must be set separately to turn the

Timer on.

Table 7. Timer/Counter 2 Used as a Timer

T2CON

Mode

Internal

Control(1)

External

Control(2)

16-Bit Auto-Reload

00H

08H

16-Bit Capture

01H

09H

Baud Rate Generator Receive

34H

36H

and Transmit Same Baud Rate

Receive Only

24H

26H

Transmit Only

14H

16H

Table 8. Timer/Counter 2 Used as a Counter

T2CON

Mode

Internal

Control(1)

External

Control(2)

16-Bit Auto-Reload

16-Bit Capture

02H

0AH

03H

0BH

Notes:

1. Capture/Reload occurs only on Timer/Counter overflow.

2. Capture/Reload occurs on Timer/Counter overflow and a

1 to 0 transition on T2EX (P1.1) pin except when Timer 2

is used in the baud rate generating mode.

Serial Interface

The Serial port is full duplex, which means it can transmit

and receive simultaneously. It is also receive-buffered,

which means it can begin receiving a second byte before a

previously received byte has been read from the receive

register. (However, if the first byte still has not been read

when reception of the second byte is complete, one of the

bytes will be lost.) The serial port receive and transmit

registers are both accessed at Special Function Register

SBUF. Writing to SBUF loads the transmit register, and

reading SBUF accesses a physically separate receive

register.

The serial port can operate in the following four modes:

Mode 0:

Serial data enters and exits through RXD. TXD outputs the

shift clock. Eight data bits are transmitted/received, with

the LSB first. The baud rate is fixed at 1/12 the oscillator

frequency (see Figure 9).

Mode 1:

Ten bits are transmitted (through TXD) or received

(through RXD): a start bit (0), eight data bits (LSB first),

and a stop bit (1). On receive, the stop bit goes into RB8 in

Special Function Register SCON. The baud rate is variable

(see Figure 10).

Mode 2:

Eleven bits are transmitted (through TXD) or received

(through RXD): a start bit (0), eight data bits (LSB first), a

programmable ninth data bit, and a stop bit (1). On

transmit, the ninth data bit (TB8 in SCON) can be assigned

the value of 0 or 1. Or, for example, the parity bit (P, in the

PSW) can be moved into TB8. On receive, the ninth data

bit goes into RB8 in Special Function Register SCON,

while the stop bit is ignored. The baud rate is

programmable to either 1/32 or 1/64 the oscillator

frequency (see Figure 11).

Mode 3:

Eleven bits are transmitted (through TXD) or received

(through RXD): a start bit (0), eight data bits (LSB first), a

programmable ninth data bit, and a stop bit (1). In fact,

Mode 3 is the same as Mode 2 in all respects except the

baud rate, which is variable in Mode 3 (see Figure 12).

In all four modes, transmission is initiated by any

instruction that uses SBUF as a destination register.

Reception is initiated in Mode 0 by the condition RI = 0 and

REN = 1. Reception is initiated in the other modes by the

incoming start bit if REN = 1.

(July, 2002, Version 1.0)

19

AMIC Technology, Inc.

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