M16C26 Datasheet, PDF (111/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

Udenvdeelropment
Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative
Three-Phase Motor Control Timer Function
and
subject to change.
SINGLE-CHIP 16-BIT
M16C/26 Group
CMOS MICROCOMPUTER
Figures 1.14.1 to 1.14.5 show registers related to timers for three-phase motor control.
Sawtooth modulation
To generate a PWM waveform of sawtooth wave modulation, set “1” in the modulation mode select bit (bit
6 at 034816). Also, set “0” in the timers A4-1, A1-1, and A2-1 control bit (bit 1 at 034916). In this mode, the
timer registers of timers A4, A1, and A2 comprise conventional timers A4, A1, and A2 alone, and reload
the corresponding timer register’s content to the counter every time the timer B2 counter’s content be-
comes 000016. The effective interrupt output specification bit (bit 1 at 034816) and the effective interrupt
output polarity select bit (bit 0 at 034816) go nullified.
An example of U phase waveform is shown in Figure 1.14.10, and the description of waveform output
workings is given below. Set “1” in DU0 (bit 0 at 034A16), and set “0” in DUB0 (bit 1 at 034A16). In addition,
set “0” in DU1 (bit 0 at 034A16) and set “1” in DUB1 (bit 1 at 034A16).
When the timber B2 counter’s content becomes 000016, timer B2 generates an interrupt, and timer A4
starts outputting one-shot pulses at the same time. In this instance, the contents of the three-phase buffer
registers DU1 and DU0 are set in the three-phase output shift register (U phase), and the contents of
DUB1 and DUB0 are set in the three-phase output shift register (U phase). After this, the three-phase
buffer register’s content is set in the three-phase shift register every time the timer B2 counter’s content
becomes 000016.
The value of DU0 and that of DUB0 are output to the U terminal (P80) and to the U terminal (P81)
respectively. When the timer A4 counter counts the value written to timer A4 (038F16, 038E16) and when
timer A4 finishes outputting one-shot pulses, the three-phase output shift register’s content is shifted one
position, and the value of DU1 and that of DUB1 are output to the U phase output signal and to the U
output signal respectively. At this time, one-shot pulses are output from the timer for setting dead time
used for setting the time over which the “L” level of the U phase waveform doesn’t lap over the “L” level of
the U phase waveform, which has the opposite phase of the former. The U phase waveform output that
started from the “H” level keeps its level until the timer for setting dead time finishes outputting one-shot
pulses even though the three-phase output shift register’s content changes from “1” to “0 ”by the effect of
the one-shot pulses. When the timer for setting dead time finishes outputting one-shot pulses, 0 already
shifted in the three-phase shift register goes effective, and the U phase waveform changes to the “L”
level. When the timer B2 counter’s content becomes 000016, the contents of the three-phase buffer
registers DU1 and DU0 are set in the three-phase output shift register (U phase), and the contents of
DUB1 and DUB0 are set in the three-phase output shift register (U phase) again.
A U phase waveform is generated by these workings repeatedly. With the exception that the three-phase
output shift register on the U phase side is used, the workings in generating a U phase waveform, which
has the opposite phase of the U phase waveform, are the same as in generating a U phase waveform. In
this way, a waveform can be picked up from the applicable terminal in a manner in which the “L” level of
the U phase waveform doesn’t lap over that of the U phase waveform, which has the opposite phase of
the U phase waveform. The width of the “L” level too can be adjusted by varying the values of timer B2
and timer A4. In dealing with the V and W phases, and V and W phases, the latter are of opposite phase
of the former, have the corresponding timers work similarly to dealing with the U and U phases to gener-
ate an intended waveform.
Setting “1” both in DUB0 and in DUB1 provides a means to output the U phase alone and to fix the U
phase output to “H” as shown in Figure 1.14.11.
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