AN1712 datasheet(12/14 Pages) STMICROELECTRONICS

Part #	AN1712

Description	GENERATING A HIGH RESOLUTION SINEWAVE USING ST7 PWMART

PDF	14 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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GENERATING A HIGH RESOLUTION SINEWAVE USING ST7 PWMART

4 HARDWARE CONFIGURATION

This application runs on an ST72F321 microcontroller. The PWM0 channel is used to gen-

erate the PWM signal which is then filtered by low pass filter (a simple RC circuit in this ex-

ample) to generate a sinusoid. The Rext used is 1.8K and Cext is 0.47uf. The values of Rext and

Cext decides the filtering level.

The selected crystal for this example has a frequency of 8 MHz which gives fCPU = 4 MHz be-

cause the PLL is disabled and slow mode is not selected. It gives the fCOUNTER = 4 MHz for

the reset value of Counter Clock Control bits in ARTCSR register.

Figure 7. Generation of sinewave: Application circuitry

ST7

8 MHz

PWM0/PB3

/\/\/\/\/\/\

Rext=1.8K

VDD_0, VDD_1, VDD_2

VDD

VSS_0, VSS_1, VSS_2

27 pf

OSC1

OSC2

Cext=0.47 uf

VPP/ICCSEL

C = 0.1 uf

AN1712 Datasheet(PDF) 12 Page - STMicroelectronics