R01UH0823EJ0100 Rev.1.00
Page 731 of 1823
Jul 31, 2019
RX23W Group
26. 8-Bit Timer (TMR)
26.2
Register Descriptions
26.2.1
Timer Counter (TCNT)
TCNT is an 8-bit readable/writable up-counter.
TMR0.TCNT and TMR1.TCNT (TMR2.TCNT and TMR3.TCNT) comprise a single 16-bit counter (TMR01.TCNT,
TMR23.TCNT) so they can be accessed together by a word transfer instruction.
The TCCR.CSS[1:0] and CKS[2:0] bits are used to select a count clock.
TCNT can be cleared by an external counter reset signal, compare match A, or compare match B. Which compare match
to be used for clearing is selected by the TCR.CCLR[1:0] bits.
When TCNT overflows (its value changes from FFh to 00h), an overflow interrupt (low-level pulse) is output provided
the interrupt request is enabled by the TCR.OVIE bit.
For details on the corresponding interrupt vector number, refer to
section 15, Interrupt Controller (ICUb)
Table 26.4
Register Allocation for 16-Bit Access
Address
Register
Upper 8 Bits
Lower 8 Bits
0008 8208h
TMR01.TCNT
TMR0.TCNT
TMR1.TCNT
0008 8204h
TMR01.TCORA
TMR0.TCORA
TMR1.TCORA
0008 8206h
TMR01.TCORB
TMR0.TCORB
TMR1.TCORB
0008 820Ah
TMR01.TCCR
TMR0.TCCR
TMR1.TCCR
0008 8218h
TMR23.TCNT
TMR2.TCNT
TMR3.TCNT
0008 8214h
TMR23.TCORA
TMR2.TCORA
TMR3.TCORA
0008 8216h
TMR23.TCORB
TMR2.TCORB
TMR3.TCORB
0008 821Ah
TMR23.TCCR
TMR2.TCCR
TMR3.TCCR
Address(es): TMR0.TCNT 0008 8208h, TMR1.TCNT 0008 8209h, TMR2.TCNT 0008 8218h, TMR3.TCNT 0008 8219h,
TMR01.TCNT 0008 8208h, TMR23.TCNT 0008 8218h
TMR01.TCNT (TMR23.TCNT)
TMR0.TCNT (TMR2.TCNT)
TMR1.TCNT (TMR3.TCNT)
b7
b6
b5
b4
b3
b2
b1
b0
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0