UM0851 datasheet(217/245 Pages) STMICROELECTRONICS

Part #	UM0851

Description	SPEAr is a family of highly customizable ARM-based embedded

PDF	245 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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217 / 245 page

UM0851

Miscellaneous device drivers

Doc ID 16604 Rev 2

217/245

Figure 62.

Duty and Period

9.3.2

Software overview

The PWM driver provides a direct interface to other Linux drivers. The PWM driver can be

found at arch/arm/mach-spear300/spr_pwm_st.c. Based upon input from user drivers the

PWM is programmed by the PWM driver.

Figure 63.

PWM driver architecture

9.3.3

PWM usage in Linux

The PWM can be used from the kernel level only. User drivers must include

include/linux/pwm.h file to access functions exported from the PWM driver. There are four

channels in the PWM hardware. There numbers are 0, 1, 2 & 3. To use the PWM channels,

follow the steps described below:

Request

The user driver must request the PWM channel it wants to use. This is done using the

following function call.

/* Pwm_id: is pwm channel id, can be 0, 1, 2 or 3.

Counter clock after prescaler

Duty

Period

Kernel space

Hardware

User drivers

PWM driver

ST PWM

UM0851 Datasheet(PDF) 217 Page - STMicroelectronics