Timer Status Register (Tsr) - Hitachi SH7032 Hardware Manual

10.2.11 Timer Status Register (TSR)

The timer status register (TSR) is an eight-bit read/write register containing flags that indicate
timer counter (TCNT) overflow/underflow and general register (GRA/GRB) compare match or
input capture. These flags are interrupt sources. If the interrupt is enabled by the corresponding bit
in the timer interrupt enable register (TIER), an interrupt request is sent to the CPU. TSR is
initialized to H'F8 or H'78 by a reset and in standby mode. Each ITU channel has one TSR.
Table 10.9 Timer Status Register (TSR)
Channel
0
1
2
3
4
Bit:
Bit name:
Initial value:
R/W:
Notes: *1 Undefined
*2 Only 0 can be written, to clear the flag.
• Bits 7–3 (Reserved): Bit 7 is read as undefined. Bits 6–3 are always read as 1. The write value
to bit 7 should be 0 or 1. The write value to bits 6–3 should always be 1.
• Bit 2 (Overflow Flag (OVF)): OVF indicates that a TCNT overflow/underflow has occurred.
Bit 2: OVF
0
1
Note: A TCNT underflow occurs when the TCNT up/down-counter is functioning. It may occur in
the following cases: (1) When channel 2 is set to phase counting mode (MDF bit in TMDR is
1), or (2) when channel 3 and 4 are set to complementary PWM mode (CMD1 bit in TFCR
is 1 and CMD0 bit is 0).
246
Abbreviation
TSR0
TSR1
TSR2
TSR3
TSR4
7 6
— —
1
*
1
— —
Description
Clearing condition: Read OVF when OVF = 1, then write 0 in OVF
Setting condition: TCNT overflow from H'FFFF to H'0000 or underflow
from H'0000 to H'FFFF
Function
TSR indicates input capture, compare match and
overflow status.
5 4
— — —
1 1
— — —
3 2 1
OVF IMFB
1 0 0
2
R/(W) * R/(W) *
0
IMFA
0
2 2
R/(W) *
(Initial value)