Input/Output Pins; Register Descriptions; Timer Counter (Tcnt) - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

13.2

Input/Output Pins

Table 13.1 summarizes the pins of the 8-bit timer module.
Table 13.1 Pin Configuration
Channel Name
0 Timer output pin
Timer clock input pin
Timer reset input pin
1 Timer output pin
Timer clock input pin
Timer reset input pin
13.3

Register Descriptions

The 8-bit timer module has the following registers. For details on the module stop control register,
refer to section 21.1.2 Module Stop Control Registers H, L (MSTPCRH, MSTPCRL).
• Timer counter_0 (TCNT_0)
• Time constant register A_0 (TCORA_0)
• Time constant register B_0 (TCORB_0)
• Timer control register_0 (TCR_0)
• Timer control/status register_0 (TCSR_0)
• Timer counter_1 (TCNT_1)
• Time constant register A_1 (TCORA_1)
• Time constant register B_1 (TCORB_1)
• Timer control register_1 (TCR_1)
• Timer control/status register_1 (TCSR_1)
13.3.1

Timer Counter (TCNT)

TCNT is 8-bit up-counter. TCNT_0 and TCNT_1 comprise a single 16-bit register so they can be
accessed together by a word transfer instruction. Bits CKS2 to CKS0 in TCR are used to select a
clock. TCNT can be cleared by an external reset input or by a compare match signal A or B.
Which signal is to be used for clearing is selected by bits CCLR1 and CCLR0 in TCR. When
TCNT overflows from H'FF to H'00, OVF in TCSR is set to 1. TCNT is initialized to H'00.
Symbol I/O
TMO0 Output
TMCI0 Input
TMRI0 Input
TMO1 Output
TMCI1 Input
TMRI1 Input
Function
Outputs at compare match
Inputs external clock for counter
Inputs external reset to counter
Outputs at compare match
Inputs external clock for counter
Inputs external reset to counter
Rev. 1.0, 09/01, page 593 of 904