DM164123 Microchip Technology, DM164123 Datasheet - Page 19

• Manufacturer Part Number: DM164123
• Description: KIT MANAGEMENT SYSTEM PICDEM
• Manufacturer: Microchip Technology
• Series: PICDEM™r
• Type: MCUr

Specifications of DM164123

• Contents: PICDEM™ System Management PCB, PICkit™ Serial Analyzer, 2 CDs, Power Supply and IDE
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC16
• Features: MCLR Reset Line And Switch , In-Circuit Serial Programming, I2C Thermal Management Control
• Silicon Core Number: PIC16F
• Silicon Family Name: PIC16F8xxx
• Kit Contents: Board, Serial Analyzer, Batt, Power Supply, CDs, Guides
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: PIC16F886
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

2.1
2.2
2.3
2.4
© 2007 Microchip Technology Inc.
INTRODUCTION
HIGHLIGHTS
PICDEM™ SYSTEM MANAGEMENT AND PICKIT™ SERIAL ANALYZER
FAN SPEED CONTROL
This chapter provides background information on the System Management application
and the PICDEM System Management Board. It also provides background information
on the fan drive circuitry that is available on the board. Additional detailed information
can be found in the PICDEM System Management presentation and source code
included on the CD-ROM.
Topics covered in this chapter include:
• PICDEM™ System Management Board and PICkit™ Serial Analyzer
• Fan Speed Control
The PICDEM™ System Management emulates four I
a system management bus. The real-time clock, ADC, serial EEPROM and thermal
management controller peripherals, typically reside on the I
servers and motherboards. The PIC16F886 integrates the functions of each device on
the I
device.
The PICkit Serial Analyzer is a utility that allows control and monitoring of the I
It is able to generate the specific device calls and interpret data. This data can then be
translated to a personal computer and can be interacted with through a graphical user
interface. In the PICDEM™ System Management Board, the PICkit Serial Analyzer
takes the place of the bus master that manages the devices on the I
2.4.1
Two-wire fans provide power and ground terminals. The fan can be controlled through
low-speed (10-100 Hz) PWM.
As the duty cycle of the PWM signal increases, fan speed increases non-linearly. Fan
speed feedback can be determined by measuring the time between commutation pulse
noise that is generated on each revolution of the fan. Low-speed PWM can be
generated by PIC microcontrollers using the Enhanced Capture/Compare/PWM
module. Speed can be measured with comparator and timer peripherals.
Note:
2
C communications bus, while responding to the specific address calls for each
Two-wire Fan
Be sure to verify with the fan manufacturer that the fan specifications allow
for PWM control of input voltage.
Chapter 2. Background
PICDEM™ SYSTEM MANAGEMENT
2
C peripherals usually found on
USER’S GUIDE
2
C bus line of rack-mount
2
C bus.
DS41304B-page 15
2
C bus.