User`s guide

Programming • 29

Before loading or reading any of these individual counters, the

control byte

(Base + 7, Base + 11

)

must be loaded first. The format of control byte is:

Control Byte: (Base + 7, Base + 11)

Bit 7 6 5 4 3 2 1 0

SC1 SC0 RL1 RL0 M2 M1 M0 BCD

• SC1 & SC1 - Select Counter (Bit7 & Bit 6)

SC1 SC0 COUNTER

0 0 0

0 1 1

1 0 2

1 1 ILLEGAL

• RL1 & RL0 - Select Read/Load operation (Bit 5 & Bit 4)

RL1 RL0 OPERATION

0 0 COUNTER LATCH

0 1 READ/LOAD LSB

1 0 READ/LOAD MSB

1 1 READ/LOAD LSB FIRST, THEN MSB

• M2, M1 & M0 - Select Operating Mode (Bit 3, Bit 2, & Bit 1)

M2 M1 M0 MODE

0 0 0 0

0 0 1 1

x 1 0 2

x 1 1 3

1 0 0 4

1 0 1 5

• BCD - Select Binary/BCD Counting ( Bit 0)

BINARY COUNTER 16-BITS

BINARY CODED DECIMAL (BCD) COUNTER

(4 DECADES)

Note:

1. The count of the binary counter is from 0 up to 65,535.

2. The count of the BCD counter is from 0 up to 99,999.