HD404654 Datasheet, PDF (60/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404654 Series
Timer D is initialized to the value set in timer write register D (TWDL: $011, TWDU: $012) by
software and incremented by one at each clock input. If an input clock is applied to timer D after it has
reached $FF, an overflow is generated. In this case, if the reload timer function is enabled, timer D is
initialized to its initial value set in timer write register D; if the free-running timer function is enabled,
the timer is initialized to $00 and then incremented again.
The overflow sets the timer D interrupt request flag (IFTD: $003, bit 0). IFTD is reset by software or
MCU reset. Refer to figure 3 and table 1 for details.
• External event counter operation: Timer D is used as an external event counter by selecting the
external event input as an input clock source. In this case, pin R4₀/EVND must be set to EVND by port
mode register C (PMRC: $025).
Either falling or rising edge, or both falling and rising edges of input signals can be selected as the
external event detection edge by detection edge select register 2 (ESR2: $027). When both rising and
falling edges detection is selected, the time between the falling edge and rising edge of input signals
must be 2t_cyc or longer.
Timer D is incremented by one at each detection edge selected by detection edge select register 2
(ESR2: $027). The other operation is basically the same as the free-running/reload timer operation.
• Timer output operation: The following four output modes can be selected for timer D by setting timer
mode register D2 (TMD2: $015).
 Toggle
 0 output
 1 output
 PWM output
By selecting the timer output mode, pin R3₂/TOD is set to TOD. The output from TOD is reset low by
MCU reset.
 Toggle output: The operation is basically the same as that of timer-C’s toggle output.
 0 output: The operation is basically the same as that of timer-C’s 0 output.
 1 output: The operation is basically the same as that of timer-C’s 1 output.
 PWM output: The operation is basically the same as that of timer-C’s PWM output.
• Input capture timer operation: The input capture timer counts the clock cycles between trigger edges
input to pin EVND.
Either falling or rising edge, or both falling and rising edges of input signals can be selected as the
trigger input edge by detection edge select register 2 (ESR2: $027).
When a trigger edge is input to EVND, the count of timer D is written to timer read register D (TRDL:
$011, TRDU: $012), and the timer D interrupt request flag (IFTD: $003, bit 0) and the input capture
status flag (ICSF: $021, bit 0) are set. Timer D is reset to $00, and then incremented again. While
ICSF is set, if a trigger input edge is applied to timer D, or if timer D generates an overflow, the input
capture error flag (ICEF: $021, bit 1) is set. ICSF and ICEF are reset to 0 by MCU reset or by writing
0.
By selecting the input capture operation, pin R3₂/TOD is set to R3₂ and timer D is reset to $00.
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