FN3043 Rev 2.00

Page 8 of 17

Aug 2000

HS-82C54RH

byte only, or least significant byte and then most significant

byte).

Since the Control Word Register and the three Counter shave

separate addresses (selected by the A1, A0 inputs), and each

Control Word specifies the Counter it applies to (SC0, SC1

bits), no special instruction sequence is required. Any

programming sequence that follows the conventions above is

acceptable.

Control Word Format

A1, A0 = 11; CS = 0; RD = 1; WR = 0

D7

D6

D5

D4

D3

D2

D1

D0

SC1

SC2

RW1

RW0

M2

M1

M0

BCD

SC - SELECT COUNTER:

M - MODE:

SC1

SC0

M2

M1

M0

0

0

Select Counter 0

0

0

0

Mode 0

0

1

Select Counter 1

0

0

1

Mode 1

1

0

Select Counter 2

X

1

0

Mode 2

1

1

Read-Back Command (See Read

Operations)

X

1

1

Mode 3

RW - READ/WRITE

1

0

0

Mode 4

RW1

RW0

1

0

1

Mode 5

0

0

Counter Latch Command (See Read

Operations)



BCD - BINARY CODED DECIMAL:

0

1

Read/Write least significant byte only.

0

Binary Counter 16-bits

1

0

Read/Write most significant byte only.

1

Binary Coded Decimal (BCD) Counter (4 Decades)

1

1

Read/Write least significant byte first, then

most significant byte.

NOTE: Don’t Care bits (X) should be 0 to insure compatibility with

future products.

FIGURE 9. CONTROL WORD FORMAT

A1

A0

A1

A0

Control Word - Counter 0

1

1

Control Word - Counter 2

1

1

LSB of count - Counter 0

0

0

Control Word - Counter 1

1

1

MSB of count - Counter 0

0

0

Control Word - Counter 0

1

1

Control Word - Counter 1

1

1

LSB of count - Counter 2

1

0

LSB of count - Counter 1

0

1

MSB of count - Counter 2

1

0

MSB of count - Counter 1

0

1

LSB of count - Counter 1

0

1

Control Word - Counter 2

1

1

MSB of count - Counter 1

0

1

LSB of count - Counter 2

1

0

LSB of count - Counter 0

0

0

MSB of count - Counter 2

1

0

MSB of count - Counter 0

0

0

A1

A0

A1

A0

Control Word - Counter 0

1

1

Control Word - Counter 1

1

1

Control Word - Counter 1

1

1

Control Word - Counter 0

1

1

Control Word - Counter 2

1

1

LSB of count - Counter 1

0

1

LSB of count - Counter 2

1

0

Control Word - Counter 2

1

1

LSB of count - Counter 1

0

1

LSB of count - Counter 0

0

0

LSB of count - Counter 0

0

0

MSB of count - Counter 1

0

1

MSB of count - Counter 0

0

0

LSB of count - Counter 2

1

0

MSB of count - Counter 1

0

1

MSB of count - Counter 0

0

0

MSB of count - Counter 2

1

0

MSB of count - Counter 2

1

0

NOTE: In all four examples, all counters are programmed to Read/Write two-byte counts. These are only four of many possible programming

sequences.

FIGURE 10. A FEW POSSIBLE PROGRAMMING SEQUENCES