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10.2 Register Descriptions
10.2.1 Timer Counter (TCNT)
TCNT is an 8-bit readable and writable* up-counter.
Bit
Initial value
Read/Write
7
0
R/W
6
0
R/W
5
0
R/W
4
0
R/W
3
0
R/W
0
0
R/W
2
0
R/W
1
0
R/W
When the TME bit is set to 1 in TCSR, TCNT starts counting pulses generated from an internal
clock source selected by bits CKS2 to CKS0 in TCSR. When the count overflows (changes from
H'FF to H'00), the OVF bit is set to 1 in TCSR. TCNT is initialized to H'00 by a reset and when
the TME bit is cleared to 0.
Note: * TCNT is write-protected by a password. For details see section 10.2.4, Notes on Register
Access.