Video

Overview

This design demonstrates how to utilize the Macnica Helio SoC board to add multi-channel PWM device. This system provides 10-channel PWM signal that consists of FPGA logic, device driver and sysfs user interface.

Figure 1: Block diagram

Demonstation

This video demonstrates the creation of a sine wave using 10 cooling fan and table tennis balls. In the video, control boards are connected to the HSMC expansion connector for generating PWM signel.

Prerequisties

The following items are reuired:

Hardware requirement

• Macnica Helio Board rev.1.3
• 2GB microSDHC flash card
• Daughter board
  • DRB-THG board-HSMC version (terasic)
  • Tolerant Buffer board (Developed in NDR on universal board)
• FAN I/F board (Developed in NDR on universal board)
• FAN: 9GA0412P6H001 (Sanyo Denki)

Software requirement

• Quartus2 64-bit Version 13.1.2 Build 173 01/15/2014 SJ Web Edition
• Qsys 13.1 Build 173

Release Contents

File	Description
helio-pwm-sdimage_v1.0.tar.gz	SD Image helio-pwm-sdimage_v1.0.tar.gz is a 2GB SD card image tar file contains all the require components for demo, including Preloader, U-boot, rootfs, kernel image and device tree blob.
fpga_sof_jic_file.zip	FPGA Configuration Data archive
	Daughter Board Schematic

Quick Start Guide

  1. Write helio-pwm-sdimage_v1.0.img
    $ sudo dd if=helio-pwm-sdimage_v1.0.img of=/dev/hdx bs=1M
　2. Write " helio_ghrd_fancon.jic" file in FPGA.
　3. boot Linux
　4. login as root
　5. change working directory
　　# cd fan
　6. load the pwm driver
　　# ./fan.sh load
　7. change the PWM
　　# echo xxxx > /sys/class/pwm/pwmchip0/pwm?/duty_cycle
　　　xxxx：0~1999 (PWM duty value)
 　　　　?：0~9 (FAN No.)
　8. start the sine wave application.
　　# ./fan.sh start
 　　to stop the application for Ctrol-C

Software

Development Environment

We developed custom pwm driver, sysfs interface and application.

• Ubuntu Linux 14.02
• GSRD v13.1 Yocto Source Package

Containts

   * Driver
     * linux/driver/pwm/core.c (update)
     * linux/driver/pwm/sysfs.c (update)
     * linux/driver/pwm/pwm-socfpga.c (new)
   * SYSFS
　　　/sys/class/pwm/
　　　-- pwmchip0/
　　　　　　|-- export
　　　　　　|-- npwm
　　　　　　|-- pwm[0-9]/
　　　　　　|　　　|-- duty_cycle      (duty width)
　　　　　　|　　　|-- enable
　　　　　　|　　　|-- fan_cycle       (rotation speed of the motor)
　　　　　　|　　　|-- period          (period 4000 fixed)
　　　　　　|　　　--- polarity
　　　　　　-- unexport