Renesas H8S/2655 Series Especificaciones descargar pdf (Pagina 19)

• Timer Synchronisation

To allow timer channels in the ITU

to be used in synchronisation, it is

possible to set up two or more timers

so that they are simultaneously

written to via software and cleared by

compare matches or input captures.

When timer channels are put into this

mode then their input and output

events are also synchronised.

• Standard PWM Mode

Each timer channel can be

programmed to produce a single

phase PWM output. Thus the ITU

can output up to ﬁve separate

channels of PWM. In this mode

GRA controls the time when the pin

goes high,and GRB when the pin

goes low. Either GRA or GRB can

be set to clear the counter,thus

setting the frequency of the WM

output.

• AC Motor Control Outputs

To provide the PWM signals required

to drive AC machines, the ITU

provides two further PWM modes:

Complementary 6-phase PWM and

Reset Synchronised 6-phase PWM

(shown in Figure 15). The main

differences between these two modes

are the transition points for the

outputs and the provision of dead

time between the phase outputs.

• Phase Counting Mode

This mode ﬁnds use in servo control

systems,where the position and speed

feedback comes from a 2- phase

quadrature encoder. In this type of

encoder the waveforms output change

their phase relationship depending on

the direction of motion,as shown in

Figure 16

By utilising the phase counting mode

on the ITU, TCNT2 will count up

or down depending on the phase

of the incoming signals. Therefore,

the value of TCNT2 will reﬂect the

positional changes experienced by the

encoder.

14-bit 976.5 Hz 732.7 Hz 610 Hz 488 Hz 365 Hz

12-bit 3. 9 KHz 2.9 KHz 2. 4 KHz 2 KHz 1.5 KHz

10-bit 15.6 KHz 11.7 KHz 9. 7 KHz 7.8 KHz 5. 8 KHz

9-bit 31. 2 KHz 23.4 KHz 19.5 KHz 15.6 KHz 11.7 KHz

8-bit 62. 4 KHz 46.9 KHz 39 KHz 31. 3 KHz 23.4 KHz

7-bit 124.8 KHz 93.8 KHz 78 KHz 62.5 KHz 46. 8 KHz

PWM 16 12 10 8 6

Res. MHz MHz MHz MHz MHz

TCNT3 value

Counter cleared at compare match with GRA3

Time

GRA3

GRB3

GRA4

GRB4

H'0000

TIOCA

TIOCB

TIOCA

TOCXA

TIOCB

TOCXB

TCNT2 value

Counting up Counting down

Time

TCLKB

TCLKA

This facility removes the requirement for

extra hardware or interrupt handlers for

position monitoring. In this mode the

comparators of channel 2 can also be

used to generate interrupts, for example

when a certain position is reached.

The table below shows the PWM frequencies which can be obtained versus

device clock speed and output resolution.

Figure 15

Figure 16

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 51 52

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