AT89S852-12PC View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT89S852-12PC

8 bit Microcontroller with 8K bytes Flash

Atmel Corporation 

AT89S8252

Auto-Reload (Up or Down Counter) (Continued)

A logic 0 at T2EX makes Timer 2 count down. The timer

underflows when TH2 and TL2 equal the values stored in

RCAP2H and RCAP2L. The underflow sets the TF2 bit

and causes 0FFFFH to be reloaded into the timer regis-

ters.

The EXF2 bit toggles whenever Timer 2 overflows or un-

derflows and can be used as a 17th bit of resolution. In this

operating mode, EXF2 does not flag an interrupt.

Figure 2. Timer 2 Auto Reload Mode (DCEN = 0)

Table 9. T2MOD—Timer 2 Mode Control Register

T2MOD Address = 0C9H

Reset Value = XXXX XX00B

Not Bit Addressable

—

—

—

—

—

—

T2OE

DCEN

Bit 7

6

5

4

3

2

1

0

Symbol

—

T2OE

DCEN

Function

Not implemented, reserved for future use.

Timer 2 Output Enable bit.

When set, this bit allows Timer 2 to be configured as an up/down counter.

11

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