Timer - Renesas RX100 Series User Manual

RX13T Group
23.10.8

Timer

The timer has the following operating modes.
(1) Break Field Low Width Output Mode
This mode is for output through the TXDX12 pin of the low level over the Break Field low width at the transmission of a
Start Frame. Setting the TMR.TOMS[1:0] bits to 10b switches operation to Break Field low width output mode. The
TMR.TCSS[2:0] bits select the clock source for the counter. When the TCR.TCST bit is set to 1, the output on the
TXDX12 pin goes to the low level and counting starts. When the timer underflows, the output on the TXDX12 pin goes
to the high level and the STR.BFDF flag is set to 1. An SCIX0 interrupt is also generated if the value of the ICR.BFDIE
bit is 1. When 0 is written to the TCR.TCST bit, counting stops after reloading of registers TPRE and TCNT. After
output of the Break Field low width is completed, stop the timer before it underflows again. Figure 23.72 shows an
example of operations in Break Field low width output mode.
FFFFh
n
0000h
TCR.TCST
TXDX12 pin output
STR.BFDF
Figure 23.72 Example of Operations in Break Field Low Width Output Mode
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
n = Contents of (upper) TCNT and (lower) TPRE
Counting stops
Count started after reloading
Set to 1 by a program
The above diagram assumes the following:
ESMER: ESME = 1
PCR: TXDXPS = 0
ICR: BFDIE = 1
TMR: TOMS[1:0] = 01b
23. Serial Communications Interface (SCIg, SCIh)
Underflow
Count started
Counting stops
after reloading
Set to 0
by a program
Write 1 to
STCR.BFDCL
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