M32C8A Datasheet, PDF (190/372 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M32C/80 Series

M32C/8A Group
15. Timers (Timer B)
15.2.1 Timer Mode
In timer mode, the timer counts an internally generated count source.
Table 15.9 lists specifications of timer mode. Figure 15.27 shows a timer mode operation (Timer B).
Table 15.9 Specifications of Timer Mode
Item
Count source
f1, f8, f2n⁽¹⁾, fC32
Specification
Count operation
• Counter decrements
When the timer underflows, the contents of the reload register are reloaded
into the counter and the count continues.
Counter cycle
n + 1 fj: count source frequency
fj n: setting value of the TBi register (i=0 to 5), 0000h to FFFFh
Count start condition
The TBiS bit in the TABSR or TBSR register is set to 1 (count starts)
Count stop condition
The TBiS bit is set to 0 (count stops)
Interrupt request generation timing When the timer underflows
TBiIN pin function
Programmable I/O port
Read from timer
A read from the TBi register returns a counter value.
Write to timer
• A write to the TBi register while the count is stopped:
The value is written to both the reload register and the counter.
• A write to the TBi register while counting:
The value is written to the reload register (It is transferred to the counter at the
next reload timing).⁽²⁾
NOTES:
1. Bits CNT3 to CNT0 in the TCSPR register select no division (n = 0) or divide-by-2n (n = 1 to 15).
2. Wait for one count source cycle or more to write after the count starts.
Count starts
FFFFh
n
Contents of the counter
n = contents of the reload
register
Underflow
Reload
Count resumes
Underflow
Count stops
Reload
TBiS bit in the
TABSR or TBSR
register
IR bit in the TBiIC
register
0000h
1
0
1
0
i = 0 to 5
Set to 0 by an interrupt request acknowledged or by program
(Condition) TBiMR register: Bits TMOD1 and TMOD0 are set to 00b (timer mode).
Figure 15.27 Operation in Timer Mode (Timer B)
Rev.1.00 Jul 15, 2007 Page 173 of 352
REJ09B0385-0100