RX610 Group
19. Watchdog Timer (WDT)
R01UH0032EJ0120 Rev.1.20
Page 606 of 1006
Feb 20, 2013
(2) Reading from TCNT Counter, TCSR Register, and RSTCSR Register
These counter and registers can be read from in the same way as other registers.
TCSR is assigned to address 00088028h, TCNT to address 00088029h, and RSTCSR to address 0008802Ah. For reading,
use 8-bit access.
<Reading from TCSR>
Address: 0008 8028h (TCSR)
7
0
Data read from TCSR
Address: 0008 8029h (TCNT)
<Reading from TCNT>
7
0
Data read from TCNT
<Reading from RSTCSR>
Address: 0008 802Bh (RSTCSR)
7
0
Data read from RSTCSR
Figure 19.5 Reading from TCNT, TCSR, and RSTCSR
19.5.2
Conflict between Timer Counter (TCNT) Write and Increment
If a TCNT clock pulse is generated during a TCNT write cycle, the write takes priority and the timer counter is not
incremented. Figure 19.6 shows this operation.
TCNT input clock
TCNT
N
M
Data written to TCNT counter
PCLK
Writing to TCNT counter by CPU
Figure 19.6 Conflict between TCNT Write and Increment
19.5.3
Changing Values of Bits CKS[2:0]
If bits CKS[2:0] bits in TCSR are written to while the watchdog timer is operating, errors could occur in the
incrementation. The watchdog timer must be stopped (by clearing the TME bit in TCSR to 0) before the values of
CKS[2:0] bits in TCSR are changed.