Hitachi H8/500 Series - Input and Output Pins; Register Configuration; Register Descriptions; Timer Counter (TCNT)-HFFD4

11.1.3 Input and Output Pins
Table 11-1 lists the input and output pins of the 8-bit timer.
Table 11-1 Input and Output Pins of 8-Bit Timer
Name Abbreviation I/O Function
Timer output TMO Output Output controlled by compare-match
Timer clock input TMCI Input External clock source for the counter
Timer reset input TMRI Input External reset signal for the counter
11.1.4 Register Configuration
Table 11-2 lists the registers of the 8-bit timer.
Table 11-2 8-Bit Timer Registers
Name Abbreviation R/W Initial Value Address
Timer control register TCR R/W H'00 H'FFD0
Timer control/status register TCSR R/(W)* H'10 H'FFD1
Timer constant register A TCORA R/W H'FF H'FFD2
Timer constant register B TCORB R/W H'FF H'FFD3
Timer counter TCNT R/W H'00 H'FFD4
* Software can write a “0” to clear bits 7 to 5, but cannot write a “1” in these bits.
11.2 Register Descriptions
11.2.1 Timer Counter (TCNT)—H'FFD4
The timer counter (TCNT) is an 8-bit up-counter that increments on a pulse generated from one of
four clock sources. The clock source is selected by clock select bits 2 to 0 (CKS2 to CKS0) of the
timer control register (TCR). The CPU can always read or write the timer counter.
Bit 76543210
Initial value 00000000
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
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