M37905M4C Datasheet, PDF (41/102 Pages) Mitsubishi Electric Semiconductor – 16 BIT CMOS MICROCOMPUTER

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MITSUBISHI MICROCOMPUTERS
M37905M4C-XXXFP, M37905M4C-XXXSP
M37905M6C-XXXFP, M37905M6C-XXXSP
M37905M8C-XXXFP, M37905M8C-XXXSP
16-BIT CMOS MICROCOMPUTER
Three-phase mode 0
In selecting three-phase waveform mode, three-phase mode 0 is se-
lected by setting bit 4 of the waveform output mode register (address
A616) to “0”.
The output polarity of three-phase waveform depends on the output
polarity set toggle flip-flop. The positive waveform of the three-phase
waveform is “H” output when the toggle flip-flop is “0”; it is “L” output
when the toggle flip-flop is “1”. (Three-phase waveform is output as
a negative waveform.)
Each output polarity set toggle flip-flop has the output polarity set
buffer shown in Figure 44. When the timer A3’s counter contents be-
come 000016, the contents of output polarity set buffer are set into
the output polarity set toggle flip-flop. After that, the polarity of the
contents of output polarity set toggle flip-flop are reversed each time
completion of one-shot pulse of timer (timers A2 to A0) correspond-
ing to each phase.
Figure 45 shows an example of U-phase waveform and the output
operation is explained. Three-phase mode 0 becomes valid when
writing “0” to the U-phase output polarity set buffer (bit 5 at address
A916) and actuating the timer A3. When the counter of timer A3 be-
comes 000016, the timer A3 interrupt request signal occurs and the
timer A2 simultaneously starts one-shot pulse output. At this time,
the contents of U-phase output polarity set buffer, “0” in this case, are
set into the output polarity set toggle flip-flop 2.
When the one-shot pulse output of timer A2 is completed, the con-
tents of output polarity set toggle flip-flop 2 is reversed from “0” to “1”.
Simultaneously, the one-shot pulse of the 8-bit dead-time timer is
output for ensuring time not to overlap “L” levels of U phase wave-
form and its negative U phase waveform.
The U-phase waveform output keeps “H” level from the start until the
one-shot pulse output of the dead-time timer is completed, even if
the contents of output polarity set toggle flip-flop 2 are reversed from
“0” to “1” owing to the timer A2’s one-shot pulse output. When the
one-shot pulse output of the dead-time timer is completed, “1” of
output polarity set toggle flip-flop 2 which has been reversed be-
comes valid and the U phase waveform changes to “L” level.
Then, write “1” to the U-phase output polarity set buffer (bit 5 at ad-
dress A916) before the counter of timer A3 becomes 000016.
After that, when the counter of timer A3 becomes 000016, the timer
A2 starts one-shot pulse output. Simultaneously, the contents of U-
phase output polarity set buffer, “1” in this case, are set into the out-
put polarity set toggle flip-flop 2 and the U phase waveform remains
“L” level.
When the one-shot pulse output of timer A2 is completed, the con-
tents of output polarity set toggle flip-flop 2 is reversed from “1” to “0”.
Simultaneously, the one-shot pulse output of the dead-time timer
starts.
When the contents of output polarity set toggle flip-flop 2 are re-
versed from “1” to “0”, the U-phase waveform changes its output
level from “L” to “H” without waiting for completion of the one-shot
pulse output of the dead-time timer.
U-phase waveform is generated by repeating the operation above.
The way to generate U-phase waveform, which is the negative
phase of U-phase, is the same as that for U-phase waveform except
that the contents of output polarity set toggle flip-flop 2 are treated as
the reversed signal from the case of U-phase waveform.
In this way, U-phase waveform and U-phase waveform, having the
negative phase of U-phase, are output from the pins so that their “L”
levels do not overlap each other. The width of “L” level can be also
modified by changing the value of timer A2 or A3.
V-, W-phase waveform and V-, W-phase waveform, having their
negative phase, are similarly output according to the corresponding
timer operation.
The explanation above is an example of three-phase waveform gen-
erating due to an triangular wave modulation. Three-phase wave-
form due to a saw-tooth-wave modulation can also be generated by
fixing each beginning level of phases.
Signal output each time
Timer A3 becomes 000016
One-shot pulse output
with timer A2
Contents of output polarity
set toggle flip-flop 2
Reversed pulse output
signal with dead-time timer
U-phase waveform output
U-phase waveform output
Fig. 45 U-phase waveform output example in three-phase mode 0 (triangular wave modulation)
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