Timer Counter (Tcnt); Timer General Register (Tgr); Timer Start Register (Tstr) - Renesas H8S Series Hardware Manual

12.3.6

Timer Counter (TCNT)

The TCNT registers are 16-bit counters. The TPU has three TCNT counters, one for each channel.
The TCNT counters are initialized to H'0000 by a reset, and in hardware standby mode. The
TCNT counters cannot be accessed in 8-bit units; they must always be accessed as a 16-bit unit.
12.3.7

Timer General Register (TGR)

The TGR registers are 16-bit registers with a dual function as output compare and input capture
registers. The TPU has 16 TGR registers, four for channel 0 and two each for channels 1 and 2.
TGRC and TGRD for channel 0 can also be designated for operation as buffer registers. The TGR
registers cannot be accessed in 8-bit units; they must always be accessed as a 16-bit unit. TGR
buffer register combinations are TGRA—TGRC and TGRB—TGRD.
12.3.8

Timer Start Register (TSTR)

TSTR is an 8-bit readable/writable register that selects operation/stoppage for channels 0 to 2.
TCNT of a channel performs counting when the corresponding bit in TSTR is set to 1. When
setting the operating mode in TMDR or setting the count clock in TCR, first stop the TCNT
counter.
Bit Bit Name Initial Value R/W
7 to 3 – 0
2 CST2 0
1 CST1 0
0 CST0 0
Description
R Reserved
The initial value should not be changed.
R/W Counter Start 2 to 0 (CST2 to CST0)
R/W These bits select operation or stoppage for TCNT.
R/W If 0 is written to the CST bit during operation with the
TIOC pin designated for output, the counter stops but the
TIOC pin output compare output level is retained.
If TIOR is written to when the CST bit is cleared to 0, the
pin output level will be changed to the set initial output
value.
0: TCNT_2 to TCNT_0 count operation is stopped
1: TCNT_2 to TCNT_0 performs count operation
Section 12 16-Bit Timer Pulse Unit (TPU)
Rev. 3.00 Jul. 14, 2005 Page 331 of 986
REJ09B0098-0300