ST7FLITE39F2M3TR STMicroelectronics, ST7FLITE39F2M3TR Datasheet - Page 58

• Manufacturer Part Number: ST7FLITE39F2M3TR
• Description: IC MCU 8BIT 8K FLASH 20SOIC
• Manufacturer: STMicroelectronics
• Series: ST7r

Specifications of ST7FLITE39F2M3TR

• Core Processor: ST7
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: LINSCI, SPI
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 15
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 384 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 7x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 20-SOIC (7.5mm Width)
• For Use With: 497-8406 - BOARD STF20NM50FD/STF7LITE39BF2497-8403 - BOARD DEMO STCC08 AC SW DETECTOR497-5858 - EVAL BOARD PLAYBACK ST7FLITE497-5049 - KIT STARTER RAISONANCE ST7FLITE
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ST7LITE3xF2
DUAL 12-BIT AUTORELOAD TIMER 3 (Cont’d)
11.2.3 Functional Description
11.2.3.1 PWM Mode
This mode allows up to four Pulse Width Modulat-
ed signals to be generated on the PWMx output
pins.
PWM Frequency
The four PWM signals can have the same fre-
quency (f
cies. This is selected by the ENCNTR2 bit which
enables single timer or dual timer mode (see
ure 34
The frequency is controlled by the counter period
and the ATR register value. In dual timer mode,
PWM2 and PWM3 can be generated with a differ-
ent frequency controlled by CNTR2 and ATR2.
Following the above formula,
– If f
Duty Cycle
The duty cycle is selected by programming the
DCRx registers. These are preload registers. The
DCRx values are transferred in Active duty cycle
registers after an overflow event if the correspond-
ing transfer bit (TRANx bit) is set.
The TRAN1 bit controls the PWMx outputs driven
by counter 1 and the TRAN2 bit controls the
PWMx outputs driven by counter 2.
PWM generation and output compare are done by
comparing these active DCRx values with the
counter.
The maximum available resolution for the PWMx
duty cycle is:
where ATR is equal to 0. With this maximum reso-
lution, 0% and 100% duty cycle can be obtained
by changing the polarity.
At reset, the counter starts counting from 0.
When a upcounter overflow occurs (OVF event),
the preloaded Duty cycle values are transferred to
58/173
1
is 2 MHz (ATR register value = 4094),the mini-
mum value is 1 KHz (ATR register value = 0).
COUNTER
and
f
PWM
PWM
Resolution = 1 / (4096 - ATR)
Figure
is 4 Mhz
) or can have two different frequen-
= f
COUNTER
35).
,
the maximum value of f
/ (4096 - ATR)
PWM
Fig-
the active Duty Cycle registers and the PWMx sig-
nals are set to a high level. When the upcounter
matches the active DCRx value the PWMx signals
are set to a low level. To obtain a signal on a
PWMx pin, the contents of the corresponding ac-
tive DCRx register must be greater than the con-
tents of the ATR register.
The maximum value of ATR is 4094 because it
must be lower than the DCR value which must be
4095 in this case.
Polarity Inversion
The polarity bits can be used to invert any of the
four output signals. The inversion is synchronized
with the counter overflow if the corresponding
transfer bit in the ATCSR2 register is set (reset
value). See
Figure 36. PWM Polarity Inversion
The Data Flip Flop (DFF) applies the polarity inver-
sion when triggered by the counter overflow input.
Output Control
The PWMx output signals can be enabled or disa-
bled using the OEx bits in the PWMCR register.
ATCSR2 Register
PWMxCSR Register
PWMx
TRANx
OPx
Figure
overflow
counter
36.
DFF
inverter
PWMx
PIN