ST7260E1 STMicroelectronics, ST7260E1 Datasheet - Page 60

• Manufacturer Part Number: ST7260E1
• Description: LOW SPEED USB 8-BIT MCU FAMILY WITH UP TO 8K FLASH/ROM AND SERIAL COMMUNICATION INTERFACE (SCI)
• Manufacturer: STMicroelectronics

Specifications of ST7260E1

• 4 Or 8 Kbytes Program Memory: high density Flash (HDFlash), or FastROM with readout and write protection

Watchdog timer (WDG)
60/139
Figure 36. Pulse width modulation mode timing example with two output compare
1. OC1R = 2ED0h, OC2R = 34E2, OLVL1 = 0, OLVL2 = 1
2. On timers with only one Output Compare register, a fixed frequency PWM signal can be generated using
Pulse width modulation mode
Pulse Width Modulation (PWM) mode enables the generation of a signal with a frequency
and pulse length determined by the value of the OC1R and OC2R registers.
Pulse Width Modulation mode uses the complete Output Compare 1 function plus the
OC2R register, and so this functionality can not be used when PWM mode is activated.
In PWM mode, double buffering is implemented on the output compare registers. Any new
values written in the OC1R and OC2R registers are taken into account only at the end of the
PWM period (OC2) to avoid spikes on the PWM output pin (OCMP1).
Procedure
To use Pulse Width Modulation mode:
1.
2.
3.
4.
the output compare and the counter overflow to define the pulse length.
Load the OC2R register with the value corresponding to the period of the signal using
the formula below.
Load the OC1R register with the value corresponding to the period of the pulse if
(OLVL1 = 0 and OLVL2 = 1) using the formula in the opposite column.
Select the following in the CR1 register:
–
–
Select the following in the CR2 register:
–
–
–
Using the OLVL1 bit, select the level to be applied to the OCMP1 pin after a
successful comparison with the OC1R register.
Using the OLVL2 bit, select the level to be applied to the OCMP1 pin after a
successful comparison with the OC2R register.
Set OC1E bit: the OCMP1 pin is then dedicated to the output compare 1 function.
Set the PWM bit.
Select the timer clock (CC[1:0]) (see
functions
Counter 34E2
OCMP1
compare2
(1)(2)
FFFC FFFD FFFE
OLVL2
Table
compare1
2ED0 2ED1 2ED2
32).
OLVL1
compare2
34E2
OLVL2
FFFC
ST7260xx