hd66100 Renesas Electronics Corporation., hd66100 Datasheet - Page 263

• Manufacturer Part Number: hd66100
• Description: H8/3867 Series
• Manufacturer: Renesas Electronics Corporation.

ECH and ECL can be used as 8-bit event counters by carrying out the software processing shown
in the example in figure 9.20. The 8-bit event counter operating clock source is asynchronous
event input from the AEVH pin for ECH, and asynchronous event input from the AEVL pin for
ECL. When the next clock is input after the ECH count value reaches H'FF, ECH overflows, the
OVH flag is set to 1 in ECCSR, the ECH count value returns to H'00, and counting up is restarted.
Similarly, when the next clock is input after the ECL count value reaches H'FF, ECL overflows,
the OVL flag is set to 1 in ECCSR, the ECL count value returns to H'00, and counting up is
restarted. When overflow occurs, the IRREC bit is set to 1 in IRR2. If the IENEC bit in IENR2 is
1 at this time, an interrupt request is sent to the CPU.
9.7.4
Asynchronous event counter operation modes are shown in table 9.21.
Table 9.21 Asynchronous Event Counter Operation Modes
Operation Mode
ECCSR
ECH
ECL
Note: * When an asynchronous external event is input, the counter increments but the counter
248
Figure 9.20 Example of Software Processing when Using ECH and ECL as 8-Bit Event
overflow H/L flags are not affected.
Asynchronous Event Counter Operation Modes
Clear OVH to 0
Set CH2 to 1
Clear CUEH, CUEL, CRCH, and CRCL to 0
Set CUEH, CUEL, CRCH, and CRCL to 1
Reset Active
Reset Functions Functions Held*
Reset Functions Functions* Functions* Functions Functions Functions* Halted
Reset Functions Functions* Functions* Functions Functions Functions* Halted
Sleep
Counters
Start
End
Watch
Sub-
active
Functions Functions Held*
Sub-
sleep
Standby
Module
Standby
Held