M16C62N Datasheet, PDF (75/213 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Timer A
Mitsubishi microcomputers
M16C / 62N Group (80-pin)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
(2) Event counter mode
In this mode, the timer counts an external signal or an internal timer’s overflow. Timers A0 and A1 can
count a single-phase external signal. Timers A2, A3, and A4 can count a single-phase and a two-phase
external signal. Table 1.13.2 lists timer specifications when counting a single-phase external signal.
Figure 1.13.8 shows the timer Ai mode register in event counter mode.
Table 1.13.3 lists timer specifications when counting a two-phase external signal. Figure 1.13.9 shows
the timer Ai mode register in event counter mode.
Table 1.13.2. Timer specifications in event counter mode (when not processing two-phase pulse signal)
Item
Specification
Count source
• External signals input to TAiIN pin (effective edge can be selected by software)
• TB2 overflow, TAj overflow
Count operation
• Up count or down count can be selected by external signal or software
• When the timer overflows or underflows, it reloads the reload register con
tents before continuing counting (Note)
Divide ratio
1/ (FFFF16 - n + 1) for up count
1/ (n + 1) for down count
n : Set value
Count start condition
Count start flag is set (= 1)
Count stop condition
Count start flag is reset (= 0)
Interrupt request generation timing The timer overflows or underflows
TAiIN pin function
Programmable I/O port or count source input
TAiOUT pin function
Programmable I/O port, pulse output, or up/down count select input
Read from timer
Count value can be read out by reading timer Ai register
Write to timer
• When counting stopped
When a value is written to timer Ai register, it is written to both reload register and counter
• When counting in progress
When a value is written to timer Ai register, it is written to only reload register
(Transferred to counter at next reload time)
Select function
• Free-run count function
Even when the timer overflows or underflows, the reload register content is not reloaded to it
• Pulse output function
Each time the timer overflows or underflows, the TAiOUT pin’s polarity is reversed
Note 1: This does not apply when the free-run function is selected.
Note 2: Timer A1 and A2 do not have I/O port (TAiIN and TAiOUT).
Timer Ai mode register
(When not using two-phase pulse signal processing)
b7 b6 b5 b4 b3 b2 b1 b0
0
01
Symbol
Address
When reset
TAiMR(i = 0 to 4) 039616 to 039A16
0016
Bit symbol
TMOD0
TMOD1
MR0
MR1
MR2
MR3
TCK0
Bit name
Function
RW
Operation mode select bit ^{b1 b0}
0 1 : Event counter mode (Note 1)
Pulse output function
select bit (Note 5)
0 : Pulse is not output
(TAiOUT pin is a normal port pin)
1 : Pulse is output (Note 2)
(TAiOUT pin is a pulse output pin)
Count polarity
select bit (Note 3, 5)
0 : Counts external signal's falling edge
1 : Counts external signal's rising edge
Up/down switching
0 : Up/down flag's content
cause select bit (Note 5) 1 : TAiOUT pin's input signal (Note 4)
0 (Must always be “0” in event counter mode)
Count operation type
select bit
0 : Reload type
1 : Free-run type
TCK1
Invalid when not using two-phase pulse signal processing
Can be “0” or “1”
Note 1: In event counter mode, the count source is selected by the event / trigger select bit
(addresses 038216 and 038316).
Note 2: The settings of the corresponding port register and port direction register are invalid.
Note 3: Valid only when counting an external signal.
Note 4: When an “L” signal is input to the TAiOUT pin, the downcount is activated. When “H”,
the upcount is activated. Set the corresponding port direction register to “0”.
Note 5: Set these bits “0” in timer A1 and A2 mode registers.
Figure 1.13.8. Timer Ai mode register in event counter mode
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