ZAMC4100GA2R datasheet(69/156 Pages) RENESAS

69 / 156 page

ZAMC4100 Datasheet

January 26, 2016

When all bits of PWMDREN are 0 (power-on-reset value), there is no driver using PWM control. In this case, the

PWM module is automatically disabled even if PWMDCFG is not 0.

3.10.2. PWM Signal Generation

The PWM module is enabled when at least one bit of the PWMDREN register is set (see section 3.10.3). In that

case, a signal with an adjustable frequency and duty-cycle is generated at the output of the PWM module (see

Figure 3.16).

Figure 3.16 PWM Output Signal

PWMDCFG

PWMFCFG

PWM

signal

PWMDCFG

PWMFCFG

The PWM frequency is configured via register PWMFCFG and is calculated using the formula:

[

]

255

]

[

]

[

256

)

(

∈

→

PWMFCFG

Fosch

PWMfreq

The value of PWMFCFG determines the division ratio of the PWM prescaler (see Figure 3.15). The prescaler

determines the speed of incrementing the PWM counter value from 0 to 255, i.e. the duration of the PWM period.

Setting a minimum value for PWMFCFG provides a maximum PWM frequency of approximately 976Hz. Each

time the counter crosses zero, the following procedure is executed:

1) The comparator (PWM) output is set to high (if PWMDCFG = 0, the output is not set)

2) The PWM duty-cycle value from register PWMDCFG is latched to the shadow register (see Figure 3.15).

The PWM output stays high as long as the counter value is less than the value configured in register PWMDCFG.

When counter’s value matches the value of PWMDCFG, the comparator (PWM) output is cleared. This is the end

of the PWM duty cycle. The PWM duty cycle is calculated using the following formula:

[

]

255

PWMDCFG

[%]

100

256

]

PWMDCFG

[

PWMdc

∈

→

A duty-cycle of 50% is achieved by writing the value 128DEC in register PWMDCFG. Writing 0 to PWMDCFG

produces a continuous low level at the output of PWM module. The maximum PWMDCFG value 255DEC produces

a duty-cycle of 99.6%.

Note: In order to have a continuously enabled driver (i.e. duty-cycle of 100%), the MCU should clear the

corresponding PWM enable of register PWMDREN.

ZAMC4100GA2R Datasheet(PDF) 69 Page - Renesas Technology Corp

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