ST7L19 datasheet(57/138 Pages) STMICROELECTRONICS

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ST7L15, ST7L19

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DUAL 12-BIT AUTORELOAD TIMER 4 (cont’d)

11.2.3.3 Break Function

The break function can be used to perform an

emergency shutdown of the application being driv-

en by the PWM signals.

The break function is activated by the external

BREAK pin. In order to use the break function it

must be previously enabled by software setting the

BPEN bit in the BREAKCR register.

The Break active level can be programmed by the

BREDGE bit in the BREAKCR register (in ROM

devices the active level is not programmable; the

break active level is low level). When an active lev-

el is detected on the BREAK pin, the BA bit is set

and the break function is activated. In this case,

the PWM signals are forced to BREAK value if the

respective OEx bit is set in the PWMCR register.

Software can set the BA bit to activate the break

function without using the BREAK pin. The BREN1

and BREN2 bits in the BREAKEN Register are

used to enable the break activation on the two

counters respectively. In Dual Timer Mode, the

break for PWM2 and PWM3 is enabled by the

BREN2 bit. In Single Timer Mode, the BREN1 bit

enables the break for all PWM channels. In ROM

devices, BREN1 and BREN2 are both forced by

hardware at high level and all PWMs are enabled.

When a break function is activated (BA bit = 1 and

BREN1/BREN2 = 1):

– The break pattern (PWM[3:0] bits in the

BREAKCR is forced directly on the PWMx output

pins if respective OEx is set (after the inverter).

– The 12-bit PWM counter CNTR1 is put to its re-

set value, that is 00h (if BREN1 = 1).

– The 12-bit PWM counter CNTR2 is put to its re-

set value, that is 00h (if BREN2 = 1).

– ATR1, ATR2, Preload and Active DCRx are put

to their reset values.

– Counters stop counting.

When the break function is deactivated after ap-

plying the break (BA bit goes from 1 to 0 by soft-

ware), the Timer takes the control of the PWM

ports.

Figure 38. Block Diagram of Break Function

PWM0

PWM1

PWM2

PWM3

PWM0

PWM1

PWM2

PWM3

BREAKCR Register

BREAK pin

(Inverters)

PWM0

PWM1

PWM2

PWM3

BPEN

Level

Selection

BREDGE BREAKCR Register

ENCNTR2 bit

BREN1

BREN2

BREAKEN Register

PWM0/1 Break Enable

PWM2/3 Break Enable

OEx

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