ST92F124 datasheet(175/429 Pages) STMICROELECTRONICS

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EXTENDED FUNCTION TIMER (EFT)

EXTENDED FUNCTION TIMER (Cont’d)

10.3.3.5 Forced Compare Mode

In this section i may represent 1 or 2.

The following bits of the CR1 register are used:

When the FOLV1 bit is set, the OLVL1 bit is copied

to the OCMP1 pin if PWM and OPM are both

cleared.

When the FOLV2 bit is set, the OLVL2 bit is copied

to the OCMP2 pin.

The OLVLi bit has to be toggled in order to toggle

the OCMPi pin when it is enabled (OCiE bit=1).

Notes:

– The OCFi bit is not set when FOLVi is set, and

thus no interrupt request is generated.

– The OCFi bit can be set if OCiR = Counter and

an interrupt can be generated if enabled. This

can be avoided by writing in the OCiHR register.

The output compare function is inhibited till

OCiLR is also written.

– The Input Capture function works in Forced com-

pare mode. To disable it, read the ICiHR register.

Input capture will be inhibited till ICiLR is read.

10.3.3.6 One Pulse Mode

One Pulse mode enables the generation of a

pulse when an external event occurs. This mode is

selected via the OPM bit in the CR2 register.

The one pulse mode uses the Input Capture1

function and the Output Compare1 function.

Procedure

To use one pulse mode, select the following in the

the CR1 register:

– Using the OLVL1 bit, select the level to be ap-

plied to the OCMP1 pin after the pulse.

– Using the OLVL2 bit, select the level to be ap-

plied to the OCMP1 pin during the pulse.

– Select the edge of the active transition on the

ICAP1 pin with the IEDG1 bit.

And select the following in the CR2 register:

– Set the OC1E bit, the OCMP1 pin is then dedi-

cated to the Output Compare 1 function.

– Set the OPM bit.

– Select the timer clock CC[1:0] (see Table 36).

Load the OC1R register with the value corre-

sponding to the length of the pulse (see the formu-

la in Section 10.3.3.7).

Then, on a valid event on the ICAP1 pin, the coun-

ter is initialized to FFFCh and OLVL2 bit is loaded

on the OCMP1 pin. When the value of the counter

is equal to the value of the contents of the OC1R

pin, (See Figure 99).

Notes:

– The OCF1 bit cannot be set by hardware in one

pulse mode but the OCF2 bit can generate an

Output Compare interrupt.

– The ICF1 bit is set when an active edge occurs

and can generate an interrupt if the ICIE bit is set

or ICIE is reset and IC1IE is set. The IC1R regis-

ter will have the value FFFCh.

– When the Pulse Width Modulation (PWM) and

One Pulse Mode (OPM) bits are both set, the

PWM mode is the only active one.

– When One Pulse Mode (OPM) and Forced Com-

pare 1 mode (FOLV1) bits are set then OPM is

the active mode

– Forced Compare 2 mode works in OPM

– Input Capture 2 function works in OPM

– When OC1R = FFFCh in OPM, then a pulse of

width FFFCh is generated

– If IC1HR register is read in OPM before an active

edge of ICAP1, then OPM is inhibited till IC1LR

is also read.

FOLV2 FOLV1 OLVL2

OLVL1

event occurs

Counter is

initialized

to FFFCh

OCMP1 = OLVL2

Counter

= OC1R

OCMP1 = OLVL1

When

on ICAP1

One pulse mode cycle

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