TS68230 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

TS68230

HMOS PARALLEL INTERFACE/TIMER

STMicroelectronics 

TS68230

counter preload register or continues counting when zero detect is reached ; bit 3 is unused and is read as zero

; bits 2 and 1 configure the path from the CLK and TIN pins to the counter controller ; and bit 0 ena-bles the timer.

This register is readable and writable at all times. All bits are cleared to zero when the RESET pin is asserted.

TCR

765

00X

01X

100

101

110

111

TOUT/TIACK Control

The dual-function pins PC3/TOUT and PC7/TIACK carry the port C function.

The dual-function pin PC3/TOUT carries the TOUT function. In the run state it is used as a square-

wave output and is toggled on zero detect. The TOUT pin is high while in the halt state. The dual-

function pin PC7/TIACK carries the PC7 function.

The dual-function pin PC3/TOUT carries the TOUT function. In the run or halt state it is used as

a timer interrupt request output. The timer interrupt is disabled, thus, the pin is always three stated.

The dual-function pin PC7/TIACK carries the TIACK function ; however, since interrupt request is

negated, the PI/T produces no response (i.e., no data or DTACK) to an asserted TIACK. Refer to

5.1.3. Timer Interrupt Acknowledge Cycles for details.

The dual-function pin PC3/TOUT carries the TOUT function and is used as a timer interrupt request

output. The timer interrupt is enabled ; thus, the pin is low when the timer ZDS status bit is one.

The dual-function pin PC7/TIACK carries the TIACK function and is used as a timer interrupt ac-

knowledge input. Refer to the 5.1.3. Timer Interrupt Acknowledge Cycles for details. This combi-

nation supports vectored timer interrupts.

The dual-function pin PC3/TOUT function. In the run or halt state it is used as a timer interrupt

request output. The timer interrupt is disabled ; thus, the pin is always three-stated. The dual-func-

tion pin PC7/TIACK carries the PC7 function.

The dual-function pin PC3/TOUT carries the TOUT function and is used as a timer interrupt request

output. The timer interrupt is enabled ; thus, the pin is low when the timer ZDS status bit is one.

The dual-function pin PC7/TIACK carries the PC7 function and autovectored interrupts are sup-

ported.

TCR

4

0

1

Zero Detect Control

The counter is loaded from the counter preload register on the first clock to the 24-bit counter after

zero detect, then resumes counting.

The counter rolls over on zero detect, then continues counting.

TCR

3

Unused and is always read as zero.

TCR

21

00

01

10

Clock Control

The PC2/TIN input pin carries the port C function, and the CLK pin and prescaler are used. The

prescaler is decremented on the falling transition of the CLK pin ; the 24-bit counter is decremented,

rolls over, or is loaded from the counter preload registers when the prescaler rolls over from $OO

to $1F. The timer enable bit determines whether the timer is in the run or halt state.

The PC2/TIN pin serves as a timer input, and the CLK pin and prescaler are used. The prescaler

is decremented on the falling transition of the CLK pin ; the 24-bit counter is decremented, rolls

over, or is loaded from the counter preload registers when the prescaler rolls over from $00 to $1F.

The timer is in the run state when the timer enable bit is one and the TIN pin is high ; otherwise,

the timer is in the halt state.

The PC2/TIN pin serves as a timer input and the prescaler is used. The prescaler is decremented

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