
R8C/14 Group, R8C/15 Group 13. Timers
Rev.2.10 Jan 19, 2006 Page 103 of 253
REJ09B0164-0210
13.2.1 Timer Mode
Timer mode is mode to count a count source which is internally generated or Timer X underflow (see
Table 13.7 Specification of Timer Mode). The TZSC register is unused in timer mode. Figure 13.16
shows the TZMR and PUM Registers in Timer Mode.
NOTES:
1. The IR bit in the TZIC register is set to “1” (interrupt requested) when writing to the TZPR or PREZ
register while both of the following conditions are met.
<Conditions>
• TZWC bit in TZMR register is set to “0” (write to reload register and counter simultaneously)
• TZS bit in TZMR register is set to “1” (count starts)
When writing to the TZPR or PREZ register in the above state, disable an interrupt before writing.
Table 13.7 Specification of Timer Mode
Item Specification
Count Source f1, f2, f8, Timer X underflow
Count Operation • Decrement
• When the timer underflows, it reloads the reload register contents before the
count continues (When Timer Z underflows, the contents of Timer Z primary
reload register is reloaded)
Divide Ratio 1/(n+1)(m+1) fi: Count source frequency
n: setting value in PREZ register, m: setting value in TZPR register
Count Start Condition Write “1” (count starts) to the TZS bit in the TZMR register
Count Stop Condition Write “0” (count stops) to the TZS bit in the TZMR register
Interrupt Request
Generation Timing
• When Timer Z underflows [Timer Z interrupt]
TZOUT Pin Function Programmable I/O port
INT0
Pin Function Programmable I/O port, or INT0 interrupt input
Read from Timer The count value can be read out by reading the TZPR and PREZ registers
Write to Timer
(1)
• When writing to the TZPR and PREZ registers while the count stops, the value is
written to both the reload register and counter.
• When writing to the TZPR and PREZ registers during the count while the TZWC
bit is set to “0” (writing to the reload register and counter simultaneously), the
value is written to each reload register of the TZPR and PREZ registers at the
following count source input and the data is transferred to the counter at the
second count source input and the count re-starts at the third count source input.
When the TZWC bit is set to “1” (writing to only the reload register), the value is
written to each reload register of the TZPR and PREZ registers (the data is
transferred to the counter at the following reload).
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