ST7FMC2N6B6(2004) View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

ST7FMC2N6B6
(Rev.:2004)

8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, BRUSHLESS MOTOR CONTROL, FIVE TIMERS, SPI, LINSCI™

STMicroelectronics 

ST7MC1/ST7MC2

MOTOR CONTROLLER (Cont’d)

Depending on the frequency and the duty cycle of

the PWM signal, the delay inserted before sam-

pling could cause it sample the signal OFF time in-

stead of the ON time. In this case an interrupt can

be generated and the sample will not be taken into

acount. When a sample occurs outside the PWM

signal ON time, the SOI bit in the MCONF register

is set and an interrupt request is generated if the

SOM bit is set in the MCONF register. This inter-

rupt is enabled only if a delay value has been set in

the DS[3:0] bits. In this case, the sampling is done

at the PWM frequency but only during the ON time

of the PWM signal. Figure 82 and Figure 83 shows

in detail the generation of the sampling order when

the delay is added.

For complete flexibility, the possibility of sampling

at 1 MHz frequency during the ON time of the

PWM signal is also available when the SPLG bit is

set as if there is a delay value in the DS[3:0] bits.

This means that when the sampling is to be per-

formed, after the delay a 1 MHz sampling window

is opened until the next OFF time of the PWM sig-

nal. The Sampling Out interrupt will be generated if

the delay added is longer than the duty cycle of the

PWM signal. As the SPLG bit is set and a value

has been put in the DS[3:0] bits, no minimum off

time is required for the PWM signal and it is auto-

matically set to 0µs in current mode. A true 100%

duty cycle can be also set in the 12-bit Timer in

voltage mode. Figure 84 shows in detail the sam-

pling at 1 MHz during ON time.

Figure 82. Adding the Delay to sample during ON time for Z detection

TSampling

New

sample

PWM signal

DS[3:0]

DS[3:0]

PWM OFF

time

Current

sample

Figure 83. Sampling Out interrupt generation

TSampling

PWM signal

DS[3:0]

PWM OFF

time

Current

SO

sample

SO

To interrupt generator

New sample during next

OFF time. Sample not taken into

account. SO interrupt generated.

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