SN8P2604A
8-Bit Micro-Controller
8.3.4 TC1R AUTO-LOAD REGISTER
TC1 timer is with auto-load function controlled by ALOAD1 bit of TC1M. When TC1C overflow occurring, TC1R value
will load to TC1C by system. It is easy to generate an accurate time, and users don’t reset TC1C during interrupt
service routine.
0DEH
TC1R
Read/Write
After reset
Bit 7
TC1R7
W
Bit 6
TC1R6
W
Bit 5
TC1R5
W
Bit 4
TC1R4
W
Bit 3
TC1R3
W
Bit 2
TC1R2
W
Bit 1
TC1R1
W
Bit 0
TC1R0
W
0
0
0
0
0
0
0
0
The equation of TC1R initial value is as following.
TC1R initial value = N - (TC1 interrupt interval time * input clock)
N is TC1 overflow boundary number. TC1 timer overflow time has five types (TC1 timer, TC1 event counter, TC1 Fcpu
clock source, PWM mode and no PWM mode). These parameters decide TC1 overflow time and valid value as follow
table.
TC1R valid
value
TC1R value
binary type
TC1CKS PWM1 ALOAD1 TC1OUT
N
0
1
1
1
1
-
x
0
0
1
1
-
x
0
1
0
1
-
256
256
64
32
16
0x00~0xFF 00000000b~11111111b
0x00~0xFF 00000000b~11111111b
0
1
0x00~0x3F
0x00~0x1F
0x00~0x0F
xx000000b~xx111111b
xxx00000b~xxx11111b
xxxx0000b~xxxx1111b
256
0x00~0xFF 00000000b~11111111b
¾
Example: To set 10ms interval time for TC1 interrupt. TC1 clock source is Fcpu (TC1KS=0) and no PWM
output (PWM1=0). High clock is external 4MHz. Fcpu=Fosc/4. Select TC1RATE=010 (Fcpu/64).
TC1R initial value = N - (TC1 interrupt interval time * input clock)
= 256 - (10ms * 4MHz / 4 / 64)
= 256 - (10-2 * 4 * 106 / 4 / 64)
= 100
= 64H
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