Chapter 8 High-speed counter, PWM / Pulse train output and Analogue I/O

(3)Effective range of PWM output on-duty values

When correcting on-duty values by setting the value that corresponds to the CPU model in the special internal output (WRF06B) for setting PWM/pulse output correction, the effective range of the on-duty values differs depending on the frequency and CPU model to be used. The effective range of the on-duty values is calculated from the following expressions. For the hardware delay time in the expressions, see Table 6.2.

Caution: There will be a slight error even if correction setting is performed.

On-duty lower limit value (%) = Hardware delay time (∝s) x Frequency used (Hz) x 10-4On-duty upper limit value (%) = 100 - Hardware delay time (∝s) x Frequency used (Hz) x 10-4

Table 8.2 Transistor output delay time for each CPU model

CPU model

Hardware delay time (TYP)

Remark

EH-***DTP

50 ∝s

 

EH-***DT

70 ∝s

 

EH-***DRP

75 ∝s

 

EH-***DRT

25 ∝s

 

Example: If the CPU model is EH-***DRP and the PWM output is 2 kHz, On-duty lower limit value = 50 x 2000 x 10-4= 10 % On-duty upper limit value = 100 - (50 x 2000 x 10-4) = 90 % Thus, the effective range of on-duty values will be 10 % to 90 %.

If correction is not performed (0 is set in WRF06B), on-duty values can be set in the range of 0 to 100 %. However, caution must be exercised since there will be an error for the period of transistor output delay time between the specified on-duty and the on-duty that is actually output.

(4)Setting abnormality

When the PI/O function setting flag (R7F5) is turned on, and a value exceeding the effective range of on-duty values is set for the on-duty setting value of each PWM output (WFR076 to WRF079), PWM outputs will not be generated.

(Example of incorrect setting) PWM output 2 kHz On-duty setting value (WRF076) - 95

(5)Individual PWM output setting

The frequency and on-duty can be set for each PWM output by the special internal outputs regardless of whether the CPU is operating or stopped. By setting “H1” in the special internal outputs listed below, it is changed to the frequencies set in the special internal outputs (WRF072 to WFR075) and the on-duty values set in the special internal outputs (WRF076 to WFR079). When changing the setting, if any of the on-duty setting values (WRF076 to WRF079) for PWM outputs is set to a value exceeding the effective range, PWM outputs will not be generated.

WRF058: PWM output 1

15

2

1

0

Not used

 

 

a

 

 

 

 

WRF059: PWM output 2

WRF05A: PWM output 3

Not used

Not used

a

a

WRF05B:

PWM output 4

Not used

a

 

 

 

 

 

 

 

 

 

Figure 8.30 Special internal outputs for setting individual PWM outputs

 

 

 

 

 

 

 

 

 

Bit

 

 

Description

 

 

 

a

 

PWM output: individual setting value change request

 

 

8-17

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Hitachi NJI-350B manual Setting abnormality, Individual PWM output setting, WRF058 PWM output