Microchip Technology MCP401X, MCP402X User’s Guide

MCP401X/2X

Digital Potentiometer

Evaluation Board

User’s Guide

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8-bit MCUs, KEEL

code hopping

MCP401X/2X EVALUATION

BOARD USER’S GUIDE

Tabl e of Conten ts

Preface ........................................................................................................................... 1

Chapter 1. Product Overview

1.1 Introduction ..................................................................................................... 5

1.2 What is the MCP402X Digital Potentiometer Evaluation Board? ................... 5

1.3 What the MCP402X Digital Potentiometer Evaluation Board Kit Includes ..... 6

Chapter 2. Installation and Operation

2.1 Introduction ..................................................................................................... 7

2.2 PCB Description ............................................................................................. 7

2.3 Test and Operating Instructions ................................................................... 10

2.4 Firmware Description ................................................................................... 17

Appendix A. Schematic and Layouts

A.1 Introduction .................................................................................................. 19

A.2 Schematic .................................................................................................. 20

A.3 MCP402X Board Layout – Top Layer + Silk-screen ................................. 21

A.4 MCP402X Board Layout – Bottom Layer ................................................. 21

A.5 MCP402X Board Layout – Top Silkscreen ............................................... 22

A.6 MCP402X Board Layout – Bottom Layer + Silk-screen ........................... 22

Appendix B. Bill Of Materials (BOM) Appendix C. Using the BFMP Programmer to Power the Board

C.1 Powering the Board Using the BFMP Programmer ..................................... 25

Appendix D. Potential Programming Issue of the MCP402XEV

D.1 Introduction .................................................................................................. 27

Appendix E. 00066_MCP402XEV.ASM Source Code

E.1 Introduction .................................................................................................. 29

Worldwide Sales and Service .................................................................................... 42

MCP401X/2X Evaluation Board User’s Guide

NOTES:

MCP401X/2X EVALUATION

BOARD USER’S GUIDE

Preface

NOTICE TO CUSTOMERS

All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available.

Documents are identified with a “DS” number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the document.

INTRODUCTION

This chapter contains general information that will be useful to know before using the MCP402X Digital Potentiometer Evaluation Board. Items discussed in this chapter include:

• Document Layout

• Conventions Used in this Guide

• Recommended Reading

• The Microchip Web Site

• Customer Support

• Document Revision History

DOCUMENT LAYOUT

This document describes how to use the MCP402X Digital Potentiometer Evaluation Board. The manual layout is as follows:

• Chapter 1. “Product Overview” – Important information about the MCP402X

Digital Potentiometer Evaluation Board.

• Chapter 2. “Installation and Operation” – Includes instructions on how to get

started with this evaluation board.

• Appendix A. “Schematic and Layouts” – Shows the schematic and layout

diagrams for the MCP402X Digital Potentiometer Evaluation Board.

• Appendix B. “Bill Of Materials (BOM)” – Lists the parts used to build the

MCP402X Digital Potentiometer Evaluation Board.

• Appendix C. “Using the BFMP Programmer to Power the Board” – Shows

how to interface the BFMP board with the MCP402X Digital Potentiometer Evaluation Board.

• Appendix D. “Potential Programming Issue of the MCP402XEV” – Discusses

possible programming issues with Rev 1 and Rev 2 of the MCP402X Digital Potentiometer Evaluation Board.

• Appendix E. “00066_MCP402XEV.ASM Source Code” – Provides information

about the application firmware, as well as the location of the source code.

MCP401X/2X Evaluation Board User’s Guide

CONVENTIONS USED IN THIS GUIDE

This manual uses the following documentation conventions:

DOCUMENTATION CONVENTIONS

Description Represents Examples

Arial font:

Italic characters Referenced books

Emphasized text ...is the

Initial caps A window the Output window

A dialog the Settings dialog A menu selection select Enable Programmer

Quotes A field name in a window or

dialog

Underlined, italic text with right angle bracket

Bold characters A dialog button Click OK

‘b

nnnn

Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>

Courier New font:

Plain Courier New Sample source code #define START

Italic Courier New A variable argument file.o, where file can be

0xnnnn A hexadecimal number where

Square brackets [ ] Optional arguments mcc18 [options] file

Curly brackets and pipe character: { | }

Ellipses... Replaces repeated text var_name [,

A menu path

A tab Click the Power tab A binary number where n is a

digit

Filenames autoexec.bat File paths c:\mcc18\h Keywords _asm, _endasm, static Command-line options -Opa+, -Opa- Bit values 0, 1

n is a hexadecimal digit

Choice of mutually exclusive arguments; an OR selection

Represents code supplied by user

MPLAB® IDE User’s Guide

“Save project before build”

File>Save

‘b00100, ‘b10

any valid filename

0xFFFF, 0x007A

[options] errorlevel {0|1}

var_name...] void main (void)

{ ... }

only

compiler...

THE MICROCHIP WEB SITE

Microchip provides online support via our web site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information:

• Product Support – Data sheets and errata, application notes and sample

programs, design resources, user’s guides and hardware support documents, latest software releases and archived software

• General Technical Support – Frequently Asked Questions (FAQs), technical

support requests, online discussion groups, Microchip consultant program member listing

• Business of Microchip – Product selector and ordering guides, latest Microchip

press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives

CUSTOMER SUPPORT

Users of Microchip products can receive assistance through several channels:

• Distributor or Representative

• Local Sales Office

• Field Application Engineer (FAE)

• Technical Support

• Development Systems Information Line Customers should contact their distributor, representative or field application engineer

(FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document.

Technical support is available through the web site at: http://support.microchip.com

Preface

DOCUMENT REVISION HISTORY

Revision B (December 2005)

• Updated to include MCP401X devices

• Enhancement of Operation Description

• Added Appendix C. “Using the BFMP Programmer to Power the Board” -

Programming the MCP402X Digital Potentiometer Evaluation Board

• Added Appendix D. “Potential Programming Issue of the MCP402XEV”- A

description of potential programming issues (and their solutions) with the MCP402X Digital Potentiometer Evaluation Board

Revision A (April 2005)

• Initial Release of this Document

MCP401X/2X Evaluation Board User’s Guide

NOTES:

MCP401X/2X EVALUATION

BOARD USER’S GUIDE

Chapter 1. Product Overview

1.1 INTRODUCTION

This chapter provides an overview of the MCP402X Digital Potentiometer Evaluation Board and covers the following topics:

• What is the MCP402X Digital Potentiometer Evaluation Board?

• What the MCP402X Digital Potentiometer Evaluation Board includes

1.2 WHAT IS THE MCP402X DIGITAL POTENTIOMETER EVALUATION BOARD?

The MCP402X Digital Potentiometer Evaluation Board (MCP402XEV) allows the system designer to quickly evaluate the operation of Microchip Technology’s MCP401X/2X Digital Potentiometer products.

The MCP402X Digital Potentiometer Evaluation Board PCB was designed to support:

• 8-pin, 150 mil SOIC MCP4021-XXX/SN devices

• SOT-23-6 MCP4022-XXX/OT devices

• SOT-23-6 MCP4023-XXX/OT devices

• SOT-23-5 MCP4024-XXX/OT devices

• 8-pin, 150 mil SOIC MCP4011-XXX/SN devices

• SOT-23-6 MCP4012-XXX/OT devices

• SOT-23-6 MCP4013-XXX/OT devices

• SOT-23-5 MCP4014-XXX/OT devices In addition to supporting the MCP401X/2X, the MCP402XEV also utilizes the SOT-23-6

PIC10F20X microcontroller. The PIC10F20X is supplied with example firmware that debounces the INCR and

DECR push buttons and generates the simple U/D MCP401X/2X to increment and decrement the potentiometer’s wiper. It also generates the simple U/D potentiometer’s wiper.

protocol required by the MCP402X to lock and unlock the

protocol required by the

MCP401X/2X Evaluation Board User’s Guide

1.3 WHAT THE MCP402X DIGITAL POTENTIOMETER EVALUATION BOARD KIT

INCLUDES

This MCP402X Digital Potentiometer Evaluation Board Kit includes:

• One populated Printed Circuit Board (PCB)

- MCP4021-103/OT

- PIC10F206-I/OT with 00066_MCP402XEV.HEX programmed into memory

- Two push button switches: one for Increment commands (INCR), one for Decrement commands (DECR)

- Decoupling capacitors

- 5 resistors to isolate the switches and create a voltage divider with the MCP4021-103/OT

• One blank PCB to allow rapid prototyping of a specific digital potentiometer configuration

• 2 samples each of the MCP4021-202/OT, MCP4021-502/OT, MCP4021-103/OT and MCP4021-503/OT

• 1 PIC10F20X-I/OT sample

• MCP401X/2X Digital Potentiometer Evaluation Board User’s Guide (electronic version on CD) (DS51546)

Chapter 2. Installation and Operation

2.1 INTRODUCTION

The MCP402X Digital Potentiometer Evaluation Board provides a tested, out-of-the-box example of a MCP401X/2X application. The circuit description is described in Section 2.2 “PCB Description”, while the test and operating instructions are described in Section 2.3 “Test and Operating Instructions”. A supplied blank PCB allows rapid prototyping of the designer’s specific MCP401X/2X device, along with other desired passive components (resistor and capacitors) and connection posts.

2.2 PCB DESCRIPTION

The MCP402X Digital Potentiometer Evaluation Board has the following features:

• 150 mil, 8-pin SOIC pinout (U1) supports the MCP4021 and MCP4011 devices

• SOT-23-6 pinout (U2) supports the MCP4022/23/24 and MCP4012/13/14 devices

• SOT-23-6 pinout (U3) supports the PIC10F20X devices

• Connection terminals can be left unpopulated for easy connection using small alligator clip leads (clamped across the edge of the board) or populated with either through-hole or surface-mount terminals

• Footprints for optional passive components for:

- Power supply filtering

- Device bypass capacitor

- Terminal “A” pull-up resistor

- Terminal “B” pull-down resistor

• Footprints for two switches:

- INCR button operation can be detected by the PIC10F20X to generate

Increment commands (move wiper toward terminal A)

- DECR button operation can be detected by the PIC10F20X to generate

Decrement commands (move wiper toward terminal B)

• Button sequence instructions are printed on the back of the PCB

Appendix A.2 “Schematic” illustrates the schematic for the MCP402XEV.

MCP401X/2X EVALUATION

BOARD USER’S GUIDE

Note: The PIC10F20X firmware (00066_MCP402XEV.HEX) must be

programmed into the microcontroller before the MCP402XEV is functional.

MCP401X/2X Evaluation Board User’s Guide

2.2.1 Evaluating the MCP4021 and MCP4011

The MCP4021/11-XXXI/SN is an 8-pin digital potentiometer device with terminals A, B and W available on the device pins. Footprint U1 supports the 150 mil SOIC package. Resistors R2 and R3 are 2.5 k MCP4021-103I/SN digital potentiometer. This creates a “windowed” voltage divider with a transfer function illustrated in Equation 2-1.

EQUATION 2-1: WINDOWED POTENTIOMETER – VOLTAGE DIVIDER

CALCULATION

wiper

Note 1: DO NOT populate U2 if using U1.

2: The MCP4011 has high-voltage tolerant pins and, therefore, accepts

high-voltage Increment and Decrement commands. Since this device is nonvolatile, the WiperLock™ Technology feature is not present.

Ω on the populated PCB, along with the 10 kΩ

DDRwb

------------------------------------------R2 R3 R

R3+()⋅

5.0V d 10k

---------------------------------------------------------------------

nom

⋅

()63⁄2.5k+()

⋅

2.5k 2.5k 10k++

Where:

d = the wiper setting (0 to 63)

2.2.2 Evaluating the MCP4022 and MCP4012

The MCP4022/12-XXXI/OT is a 6-pin, stand-alone digital rheostat with terminals A and W available on the device pins. Footprint U2 supports the SOT-23-6 package. An “INCR” command moves the wiper toward terminal A, thus causing the resistance across the rheostat to decrease. A “DECR” command moves the wiper toward terminal B, thus causing the resistance across the rheostat to increase.

Note 1: DO NOT populate U1 if using U2.

2: The included MCP4021 digital potentiometer samples could be used to

evaluate the MCP4022 simply by not populating R3 and letting terminal B float.

3: The MCP4012 has high-voltage tolerant pins and, therefore, accepts

high-voltage Increment and Decrement commands. Since this device is nonvolatile, the WiperLock™ Technology feature is not present.

Installation and Operation

2.2.3 Evaluating the MCP4023 and MCP4013

The MCP4023/13-XXXI/OT is a 6-pin, grounded digital potentiometer with terminals A and W available on the device pins. Footprint U2 supports the SOT-23-6 package. Populating R2 will create a voltage divider with a transfer function illustrated in Equation 2-2.

EQUATION 2-2: GROUNDED POTENTIOMETER – VOLTAGE DIVIDER

CALCULATION

wiper

VDDRwb⋅

-------------------------R2 R

5.0V d 10k

-----------------------------------------------

nom

Where:

d = the wiper setting (0 to 63)

Note 1: DO NOT populate U1 if using U2.

2: The included MCP4021 digital potentiometer samples could be used to

evaluate the MCP4023 simply by shorting terminal B to GND.

3: The MCP4013 has high-voltage tolerant pins and, therefore, accepts

high-voltage Increment and Decrement commands. Since this device is nonvolatile, the WiperLock™ Technology feature is not present.

⋅63⁄

()

⋅

2.5k 10k+

2.2.4 Evaluating the MCP4024 and MCP4014

The MCP4024/14-xxxI/OT is a 5-pin, grounded digital rheostat with the W terminals available on the device pins. Footprint U2 supports the SOT-23-5 package. An “INCR” command moves the wiper toward terminal A, thus causing the resistance across the rheostat to increase. A “DECR” command moves the wiper toward terminal B, thus causing the resistance across the rheostat to decrease.

Note 1: DO NOT populate U1 if using U2.

2: The included MCP4021 digital potentiometer samples could be used to

evaluate the MCP4024 simply by not populating R float and by shorting terminal B to GND.

3: The MCP4014 has high-voltage tolerant pins and, therefore, accepts

high-voltage Increment and Decrement commands. Since this device is nonvolatile, the WiperLock™ Technology feature is not present.

, letting terminal A

MCP401X/2X Evaluation Board User’s Guide

2.3 TEST AND OPERATING INSTRUCTIONS

The populated PCB is configured to create a voltage divider from VDD to VSS using a

2.5 kΩ pull-up resistor (R2), the MCP4021-103I/SN (10 kΩ) and a 2.5 kΩ pull-down resistor (R3). To quickly evaluate the digital potentiometer’s performance, the following test equipment is required:

• 2.7V to 5.5V power supply

• Voltmeter or Digital Multimeter (DMM) Figure 2-1 shows the Digital Potentiometer Evaluation Board PCB, components and

the connection points that will be used in the step-by-step demonstration.

Increment (INCR) Switch

Resistor R2 (A to VDD)

Baseline Flash MCU Programmer (BFMP) Interface

Resistor R3 (B to GND)

Decrement (DECR) Switch

FIGURE 2-1: Digital Potentiometer Evaluation Board Overview.

Digital Potentiometer Node A Pad

Digital Potentiometer Node B Pad

Digital Potentiometer Wiper W Pad

+ 32 hidden pages

Microchip Technology MCP401X, MCP402X User’s Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

INTRODUCTION

DOCUMENT LAYOUT

CONVENTIONS USED IN THIS GUIDE

RECOMMENDED READING

THE MICROCHIP WEB SITE

CUSTOMER SUPPORT

DOCUMENT REVISION HISTORY

1.1 INTRODUCTION

1.2 WHAT IS THE MCP402X DIGITAL POTENTIOMETER EVALUATION BOARD?

2.1 INTRODUCTION

2.2 PCB DESCRIPTION

2.3 TEST AND OPERATING INSTRUCTIONS