Operation As Timer Output - NEC mPD789426 Series User Manual

6.4.2 Operation as timer output

Timer outputs are repeatedly generated at the count value preset in 16-bit compare register 90 (CR90) based on
the intervals of the value set in TCL901 and TCL900.
To operate the 16-bit timer as a timer output, the following settings are required.
• Set P26 to output mode (PM26 = 0).
• Reset output latch of P26 to 0.
• Set the count value in CR90.
• Set 16-bit timer mode control register 90 (TMC90) as shown in Figure 6-7.
Figure 6-7. Settings of 16-Bit Timer Mode Control Register 90 for Timer Output Operation
TOD90 TOF90 CPT901 CPT900 TOC90 TCL901 TCL900 TOE90
−
TMC90
Caution If both the CPT901 flag and CPT900 flag are set to 0, the capture operation is prohibited.
When the count value of 16-bit timer counter 90 (TM90) matches the value set in CR90, the output status of the
TO90/P26 pin is inverted. This enables timer output. At that time, TM90 counting continues and an interrupt request
signal (INTTM90) is generated.
Figure 6-8 shows the timing of timer output (see Table 6-2 for the interval time of the 16-bit timer).
Count clock
TM90 count value
CR90
INTTM90
Note
TO90
TOF90
Note The initial value of TO90 becomes low level when output is enabled (TOE90 = 1).
Remark N = 0000H to FFFFH
CHAPTER 6 16-BIT TIMER
0/1 0/1 0/1 1
Figure 6-8. Timer Output Timing
t
0000H 0001H
N
User's Manual U15075EJ1V0UM00
0 0/1 1
TO90 output enable
Setting of count clock (see Table 6-2)
Inverse enable of timer output data
N FFFFH 0000H 0001H
N N
Interrupt
acknowledgement
Overflow flag set
N FFFFH
N N
Interrupt
acknowledgement
125