
HYUNDAI MicroElectronics
18
2.4. BASIC INTERVAL TIMER
The Basic Interval Timer(B.I.T.) has 8-bit binary counter. The operations is shown below.
. Generates reference time interval interrupt request as a timer.
. The counting value of B.I.T. can be read.
( Note; The writing at same address overwrites the CKCTLR.)
. The overflow of B.I.T be used the source clock of Watch Dog Timer.
2.4.1. Control of Basic Interval Timer
The Basic Interval Timer is free running timer. When the counting value is changed "0FFH" to
"00H" , The interrupt request flag is generated. The counter can be cleared by setting BTCL (Bit 3
of CKCTLR) and the BTCL is auto-cleared after 1 machine cycle. The initial state (after Reset) of
BTCL is
“
0
”
.
The input clock of Basic Interval Timer is selected by BTS2~BTS0 (Bit2~0 of CKCTLR) among the
prescaler outputs (PS4~PS11).
The Basic Interval Timer Register (BITR) can be read.
The CKCTLR and the BITR have a same address (00D3H). So, If you write to this address, the
CKCTLR would be controlled. If you read this address, the counting value of BITR would be read.
CLOCK CONTROL REGISTER
PS4
WDTON
ENPCK
BTCL
BTS2
BTS1
BTS0
CKCTLR
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
BITR
PS5
PS6
PS7
PS8
PS9
PS10
PS11
MUX
IFBIT
Internal Data Bus
Internal Data Bus
Same address
when read, it can be read as
counter value. When write, it can
be write as control register.
B.I.T. input clock selection
B.I.T. CLEAR ( When writing )
0 : B.I.T. Free-run
1 : B.I.T. Clear ( auto cleared after 1 machine cycle )
7
6
5
4
ENPCK
WDTON
3
BTCL
2
BTS2
1
BTS1
0
BTS0
W
W
W
W
W
W
<00D3
H
>
CKCTLR