Microchip Technology MCP1252 User Manual

MCP1252 Charge Pump

Backlight LED Demo Board

User’s Guide

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®

8-bit MCUs, KEELOQ

®

code hopping

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

Tabl e of Conten ts

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

Chapter 1. Product Overview........................................................................................5

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

1.2 What is the MCP1252 Charge Pump Backlight LED Demo Board? ...............6

1.3 What the MCP1252 Charge Pump Backlight LED Demo Board kit includes .6

Chapter 2. Installation and Operation..........................................................................7

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

2.2 Features ......................................................................................................... 7

2.3 Getting St a rt ed ...... .............. .. .. ............. .. .............. .. ............. .. ... ............. .. ....... 8

Appendix A. Schematic and Layouts.........................................................................11

A.1 Introduction ..................................................................................................11

A.2 Board – Sc h em a tic ............ ............. .. ............. ... ............. .. ............. ... .. ....... 12

A.3 Board – Top Assembly Drawing .................................................................13

A.4 Board – Top Layer + Silk-Screen .............................................................14

A.5 Board – Bottom Layer (From Top) ............................................................. 15

Appendix B. Bill-Of-Materials (BOM)..........................................................................17

Appendix C. 00016R1.asm Source Code...................................................................19

C.1 Device Fir m wa re .. .. ............. .. ............. ... ............. .. .. .............. .. ............. .. ... 19

Worldwide Sales and Service ....................................................................................26

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

NOTES:

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO 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.

For the most up-to-date information on development tools, see the MPLAB Select the Help menu, and then Topics to open a list of available on-line help files.

®

IDE on-line help.

INTRODUCTION

This chapter contains general information that will be useful to know before using the MCP1252 Charge Pump Backlight LED Demo 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 MCP1252 Charge Pump Backlight LED Demo Board. The manual layout is as follows:

• Chapter 1. “Product Overview” – Important information about the MCP1252 Charge Pump Backlight LED Demo Board.

• Chapter 2. “Installation and Operation” – Includes instructions on how to get started with this user’s guide and a description of the user’s guide.

• Appendix A. “Schematic and Layouts” – Shows the schematic and layout diagrams for the MCP1252 Charge Pump Backlight LED Demo Board.

• Appendix B. “Bill-Of-Materials (BOM)” – Lists the parts used to build the MCP1252 Charge Pump Backlight LED Demo Board.

• Appendix C. “00016R1.asm Source Code” – Provides information about the application firmware and where the sou rce co de can be found.

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

CONVENTIONS USED IN THIS GUIDE

This manual uses the following docum entat io n conven tion s:

DOCUMENTATION CONVENTIONS

Description Represents Examples

Arial font:

Italic characters Referenced books MPLAB

Emphasized text ...is the only comp ile r...

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

‘bnnnn A binary number where n is a

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

Courier font:

Plain Courier Sample source code #define START

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

0xnnnn A hexadecimal number wher e

Square brackets [ ] Optional arguments mcc18 [options] file

Curly brackets and pipe character: { | }

Ellipses... Replaces r epeated text var_name [,

A menu path File>Save

A tab Click the Power tab

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

“Save project before build”

‘b00100, ‘b10

any valid filename

0xFFFF, 0x007A

[options] errorlevel {0|1}

var_name...] void main (void)

{ ... }

®

IDE User’s Guide

Chapter 1. Product Overview

1.1 INTRODUCTION

Today’s new color displays require a pure white light for backlighting. White light-emmitting diodes have become the component of choice. The MCP1252-ADJ is an excellent choice for biasing the backlighting or driving other LED applications. Light intensity is controlled uniformly through the use of ballast resistors. The peak intensity is set by the feedback (FB) to the the MCP1252-ADJ. Dimming is accomplished by pulse-width modulating the shutdown pin of the device.

This chapter covers the following topics:

• What is the MCP1252 Charge Pump Backlight LED Demo Board?

• What the MCP1252 Charge Pump Backlight LED Demo Board Kit Includes

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

3 AAA

Battery

Pack

Power

Supply

FIGURE 1-1: MCP1252 Charge Pump Backlight LED Demo Board Block Diagram.

PIC10F206

SHDN

MCP1252

Push Button

V

OUT

FB

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

1.2 WHAT IS THE MCP1252 CHARGE PUMP BACKLIGHT LED DEMO BOARD?

The MCP1252 Charge Pump Backlight LED Demo Board demonstrates the use of a charge pump device in a LED application. The board also serves as a platform to evaluate the MCP1252 device generally.

The MCP1252-ADJ device used in this application is an in ductorless, positive-regulated charge pump DC/DC converter . The device generates an adjustable output volt age. It is specifically designed for applications requiring low noise and high efficiency, and is able to deliver up to 120 mA output current. In addition, a charge pump is a low-cost, compact and simple solution for an application, as it o nly requires one external capacitor to transfer charge from the input supply to the regulated output.

The MCP1252 allows the input voltage to be lower or higher than the the output voltage by automatically switching between buck and boost operation. This makes it especially suited for battery applications, allowing the system voltage to be maintained even after the batteries have discharged below the system voltage level, further extending the overall charge life of the battery.

1.3 WHAT THE MCP1252 CHARGE PUMP BACKLIGHT LED DEM O BOARD KIT INCLUDES

This MCP1252 Charge Pump Backlight LED Demo Board kit includes:

• MCP1252 Charge Pump Backlight LED Demo Board (102-00016)

• MCP1252 Charge Pump Backlight LED Demo Board User’s Guide (DS51551)

Chapter 2. Installation and Operation

2.1 INTRODUCTION

The MCP1252 Charge Pump Backlight LED Demo Board uses the MCP1252-ADJ to power four white LEDs. A PIC10F206 microcontroller in a SOT23 package is used to provide an enable signal to the MCP1252. It also accepts a push button input that allows the user to adjust the white LEDs to five different light intensities, in addition to placing the system in a standby mode that consumes less than 1 µA of current (typ.).

The PIC10F206 microcontroller is programmable, allowing the user to modify or develop their own firmware routines to further evaluate the MCP1252 in this application.

2.2 FEATURES

The MCP1252 Charge Pump Backlight LED Demo Board has the following features:

• Programmed MCP1252 charge pump control (via the PIC10F206)

• Four white LEDs

• PIC10F206 microcontroller

- Enables the MCP1252 charge pump

- Controls light intensity

- Places system into Sleep mode (< 1 µA)

• Push button interface for multiple control options

• Baseline Flash Microcontroller Programmer (BFMP) Header for reprogramming the PIC10F206

• 3 AAA battery pack (batteries not included)

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

f”

2.3 GETTING STARTED

The MCP1252 Charge Pump Backlight LED Demo Board comes fully assembled and tested. The board requires 3 AAA batteries as a power source for the application.

2.3.1 Powering the MCP1252 Charge Pump Backlight LED Demo Board

Insert three AAA batteries into the battery pack on the bottom of the board. As soon as the system powers up, the internal program of the PIC10F206 will initialize and remain in a low-power sleep mode (<1 µA) until the S1 button is pressed by the user.

The MCP1252 Charge Pump Backlight LED Demo Board does not need a power switch or power jumper because of the “standby” or “sleep” mode of the PIC10F206 microcontroller. Upon entering Sleep mode, the system requires less than 1 µA (typ) of current. So, with three AAA batteries used in the application (at 1250 mAh per battery), the system’s power requirements in Sleep mode are minimal (the “shelf life” of an alkaline battery is 5-7 years, whereas the system current load in Sleep mode would discharge the battery pack in about 400 years!).

“Power On/Of Push Button Switch

FIGURE 2-1: Setup Configuratio n Diagram .

Installation and Operation

Activating Application and Changing the LED intensity

1. To activate the LEDs, simply press the S1 push button. The LEDs will turn on at a low intensity level when the push button is pressed, gaining intensity when the push button is pressed again. There are 5 levels of LED intensity (plus the “off” state).

The intensity of the LEDs are controlled via the SHDN A Pulse-Width Modulated (PWM) signal is generated by the PIC10F206 and routed to the SHDN duty cycle of the PWM waveform is varied, such that narrow pulses create a low-intensity conditi on, whi le wide r pulse s cr ea te a high- in tens it y con dit ion.

2. The LEDs will be turned off, and the system will enter Sleep mode, when the LEDs are in the high-intensity state and the push button is pressed. Subsequent push button presses will cycle the LEDs as described in Step 1.

input pin of the MCP1252. The MCP1252 is actually pulsed, and the

Evaluating the Application

The best way to evaluate the MCP1252 Charge Pump Backlight LED Demo Board is to dig into the circuit. Measure voltages and currents with a DVM and probe the board with an oscilloscope. Test points have been provided to simplify this task. The test points correspond to the pins of the MCP1252: PGD (= PGOOD), Vout, V GND, SHDN

The firmware program in the PIC10F206 can also be edited to modify the operation of the application. For example, the output signal that is routed from GP0 of the PIC10F206 to SHDN intensities, slowly blinking the LEDs on/off or provide some other pattern. There is also an optional push button (S2) that can be used to provide additional control options to the system

and FB.

of the MCP1252 can be changed to implement different light

input pin of the MCP1252.

(= VIN),

DD

Firmware

The PIC10F206 comes preprogrammed with firmware to operate the system as described above. The program file can be found on the CD that comes with the kit. The file listing and firmware flow diagram are shown in Appendix C. “00016R1.asm Source Code”.

The program is fairly simple and straightforward. There is an initialization routine at the beginning of the program. The constants allow for five LED intensity levels to be adjusted to the appropriate light intensity (LED_HI_ON, LED_MEDHI_ON, etc.), set the PWM period (PERIOD) and maximum time (MAX_TIME) before the unit switches back to Sleep mode. The variables track what mode the unit is in (MODE), implement counters (COUNTER, TIMERH, TIMERL), etc.

Upon resetting the processor, the ports are initialized and registers are configured in the INIT_PORTS routine. If the device has come out of Sleep mode, the MODE variable is set so the LEDs will be at low intensity. The OPTION register is configured to wake-up on Port pin change. The GPIO port is configured to set GP0 (PWM to the MCP1252) as an output and GP1, GP2 and GP3 (push button) as inputs. The processor will reset on power-up or due to a wake-up from Sleep mode. Therefore, the ST ATUS register needs to be tested to determine the source of the reset. If the reset occurred due to powering up the system for the first time, the program proceeds to the INIT_VARS subroutine, where the program variables are initialized. If the reset occurred due to a wake-up from Sleep mode, the program proceeds to the WAKE subroutine.

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

The WAKE routine tests the GPIO push button input to determine if the button has been pressed. If it has, the program goes to the INC_MODE subroutine to set the new LED intensity mode. The INC_MODE and MODE_SELECT routines determine the appropriate light intensity when the device is reset, comes out of Sleep mode, or button S1 is pressed to increment the light intensity. The LED_FULL, LED_HIGH, LED_MEDHI, LED_MED, LED_LOW, and LED_OFF routines set one of six LED settings (five light intensity settings and “off”).

Programming

Header JP1 is provided for in-system circuit programming. This is an optional feature since the demo board comes pre-programmed with F/W to operate the system. The PIC10F206 can be reprogrammed with the Baseline Flash Microcontroller Programmer (BFMP).

The BFMP is a simple and easy-to-use in-circuit serial programmer intended to be used with any of Microchip’s new baseline Flash PIC PIC10F200/202/204/206, PIC12F508/509, PIC16F505 and PIC16F54/57/59. The BFMP provides a 6-pin linear In-Circuit Serial Programming™ (ICSP™) header for standard ICSP support, as well as stand-alone programming support for the PIC10F family when paired with the PIC10F2XX programmer adapter, providing the least expensive method of programming. The BFMP utilizes USB and does not require an external power supply. The included Graphical User Interface (GUI) allows you to read, write and verify the microcontroller to be programmed.

Please refer to Microchip’s web site (www.microchip.com) for additional information on the BFMP.

®

microcontrollers, specifically, the

Appendix A. Schematic and Layouts

A.1 INTRODUCTION

This appendix contains the following schematics and layouts for the MCP1252 Charge Pump Backlight LED Demo Board:

• Board – Schematic

• Board – Top Assembly Drawing

• Board – Top Layer + Silk-Screen

• Board – Bottom Layer

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

A.2 BOARD – SCHEMATIC

M

A.3 BOARD – TOP ASSEMBLY DRAWING

Schematic and Layouts

M

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

A.4 BOARD – TOP LAYER + SILK-SCREEN

A.5 BOARD – BOTTOM LAYER (FROM TOP)

Schematic and Layouts

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

NOTES:

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

Appendix B. Bill-Of-Materials (BOM)

TABLE B-1: BILL-OF-MATERIALS (BOM)

QTY Reference Description Manufacture MFG PART #

®

1 C2 CAP .1UF 25V CERAMIC

X7R 0805

1 C3 CAP 1.0UF 10V CERAMIC

X7R 0805

2 C4,C5 CAP 10UF 6.3V CERAMIC

X5R 1206

4 R1,R2,R3,R4 RES 15.0 OHM 1/10W 1%

0805 SMD

1 R5 RES 10.0K OHM 1/10W 1%

0805 SMD

2 R7,R12 RES 4.99K OHM 1/10W 1%

0805 SMD

3 R6,R8,R10 RES 49.9K OHM 1/10W 1%

0805 SMD

1 R11 RES 100K OHM 1/10W 1%

0805 SMD

1 R9 RES 1.00M OHM 1/10W 1%

0805 SMD

4 D1,D2,D3,D4 LED WHITE DIFFUSED 2-PLCC

SMD

2 S1,S2 SWITCH LT TOUCH 6X3.5

100GF SMD

1 BAT 1 HOLDER BATTERY 3CELL AAA

PC MNT 1 J1 SIP_6 Pin "Do Not Populate” — — 1 JP1 CONN HEADER 2POS .100

VERT TIN 1 U1 MCP1252 Microchip Technology Inc. MCP1252-ADJI/MS 1 U2 PIC10F206-E/OTG Microchip Technology Inc. PIC10F206-E/OTG

Panasonic

Kemet

Kemet C1206C106K9PACTU

Panasonic – ECG ERJ-6ENF15R0V

Panasonic – ECG ERJ-6ENF1002V

Panasonic – ECG ERJ-6ENF4991V

Panasonic – ECG ERJ-6ENF4992V

Panasonic – ECG ERJ-6ENF1003V

Panasonic – ECG ERJ-6ENF1004V

Osram Opto Semiconductors Inc

Panasonic – ECG EVQ-PJS04K

Keystone Electronics

Molex Electronics Corp

– ECG ECJ-2VB1E104K

®

/Waldom®

®

C0805C105K8RACTU

LW T67C-T2U2-3C5D

2479

22-28-4021

MCP1252 Charge Pump Backlight LED Demo Board User’s Guide

NOTES:

MCP1252 CHARGE PUMP BACKLIGHT

LED DEMO BOARD USER’S GUIDE

Appendix C. 00016R1.asm Source Code

C.1 DEVICE FIRMWARE

Software License Agreement The software supplied herewith by Microchip Technology Incorporated (the “Company”) is intended and supplied to you, the Company’s customer, for use solely and exclusively with products manufactured by the Company. The software is owned by the Company and/or its supplier, and is protected under applicable copyright laws. All rights are reserved. Any use in violation of the foregoing restrictions may subject the user to criminal sanctions under applicable laws, as well as to civil liability for the breach of the terms and conditions of this license. THIS SOFTWARE IS PROVIDED IN AN “AS IS” CONDITION. NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.

Power-Up

Initialize:

OSCCAL, Port,

PWM registers

Yes

Is this a

Power-On

Reset?

Yes

Initialize

PWM period

variables

Go To

SLEEP

Wake-Up

on pin change?

No

Wake-Up on

pin change?

No

FIGURE C-1: Firmwar e Flowchart – Page 1.

Is this

Yes

Determine New Mode

Shutdown

No

Light Intensity

Has button

been pressed?

No

Is this

Mode?

Adjust

Yes

00016R1.asm Source Code

TABLE C-1: 00016R1.ASM

;********************************************************************** ; * ; Filename: 00016R1.asm * ; Date: 31aug04 * ; File Version: pp1 * ; * ; Author: M Waldron * ; Company: MCHP * ; 10f204/ 10f206 PWM to control LED driver * ; * ;********************************************************************** ; * ; Files required: * ; * ; * ; * ;********************************************************************** ; * ; Notes: Changed file name, added led_medhi routine, * ; adjusted intensity of various modes. PB 3/29/05 * ; * ; * ; * ; * ;**********************************************************************

list p=10f206 ; list directive to define processor #include <p10f206.inc> ; processor specific variable definitions

__CONFIG _CP_OFF & _WDT_OFF & _MCLRE_OFF & _IntRC_OSC

; ‘__CONFIG’ directive is used to embed configuration data within .asm file. ; The labels following the directive are located in the respective .inc file. ; See respective data sheet for additional information on configuration word.

;constants ;increase led_xxx_on to increase intensity ( value must be less than period value) ;increase period to reduce PWM frequency and increase PWM resolution led_hi_on = 0x16 ;on loops for high brightness mode led_hi_off = 0x11 ;off loops for high brightness mode, value will be calculated by the program (10) led_medhi_on = 0x08 ;on loops for medium_high brightness mode led_medhi_off = 0x11 ;off loops for high brightness mode (11) led_med_on = 0x06 ;on loops for medium brightness mode led_med_off = 0x11 ;off loops for high brightness mode (11) led_low_on = 0x05 ;on loops for low brightness mode led_low_off = 0x12 ;off loops for high brightness mode (12) period = 0x0E ;total loops per PWM period max_time = 0xff ;on time before unit swithces back to sleep

;variables mode = 0x13 ;current mode ( high, med, lo ) counter = 0x14 ;hi and low time counter debounce = 0x15 ;debounce counter flag = 0x16 ;debounce control flags

00016R1.asm Source Code

TABLE C-1: 00016R1.ASM (CONTINUED)

timerh = 0x17 ;on timer high byte timerl = 0x18 ;on timer low byte

;bits used in the flag variable new_mode = 7 ;when set a debounced user keypress has been detected timer_ena = 6 ;when clear the debounce timer will not increment ;GPIO pins button = 3 ;mode select button pwm = 0 ;pwm output

;other TO EQU H’0004’ PD EQU H’0003’ GPWU EQU H’0007’ GPPU EQU H’0006’ COUTEN EQU H’0006’ CMPT0CS EQU H’0004’ CWU EQU H’0000’

org 0x00 goto reset

org 0x10

reset nop nop bcf OSCCAL, FOSC4 ; GP2/T0CKI/COUT applied to GP2 pin init_ports movlw 0x01 ;initalize mode, upon wake up led will be at low intensity movwf mode ; movlw b’00001111’ ;configure for wake on port change OPTION ; movlw b’01010011’ ;disable the comparator movwf 0x07 ;write to CMCON0 ; clrf GPIO movlw 0x0E tris GPIO ;configure port ; bcf STATUS, GPWUF btfsc STATUS, CWUF ;test for wake up or reset goto wake btfsc STATUS, GPWUF goto wake btfss STATUS, TO goto wake btfss STATUS, PD goto wake goto init_vars ;initialize vars

init_vars movlw 0xFF movwf timerh movwf timerl ; movlw led_hi_on ;calculate off times based on time remaining in PWM period

00016R1.asm Source Code

TABLE C-1: 00016R1.ASM (CONTINUED)

movwf led_hi_off ;add the complement of on time to the window time comf led_hi_off, f movlw period addwf led_hi_off, f ; movlw led_medhi_on ;calculate off times based on time remaining in PWM period movwf led_medhi_off ;add the complement of on time to the window time comf led_medhi_off, f movlw period addwf led_medhi_off, f ; movlw led_med_on ;calculate off times based on time remaining in PWM period

movwf led_med_off ;add the complement of on time to the window time comf led_med_off, f movlw period addwf led_med_off, f ; movlw led_low_on ;calculate off times based on time remaining in PWM period movwf led_low_off ;add the complement of on time to the window time comf led_low_off, f movlw period addwf led_low_off, f ; movf GPIO, w ;read port before entering sleep mode sleep wake btfss GPIO, button ;only allow a low to bring PIC out of sleep goto inc_mode movlw 0x20 call delay movf GPIO, w sleep ; inc_mode incf mode, f ;it was a pin change, determine new mode ;determine current mode mode_select bcf flag, new_mode ;clear new mode flag ; movlw 0x01 subwf mode, w btfsc STATUS, Z goto led_off ; movlw 0x02 subwf mode, w btfsc STATUS, Z goto led_low ; movlw 0x03 subwf mode, w btfsc STATUS, Z goto led_med ;

00016R1.asm Source Code

TABLE C-1: 00016R1.ASM (CONTINUED)

movlw 0x04 subwf mode, w btfsc STATUS, Z goto led_medhi ; movlw 0x05 subwf mode, w btfsc STATUS, Z goto led_high ; movlw 0x06 subwf mode, w btfsc STATUS, Z goto led_full ; movlw 0x01 ;on mode rollover reset to low brightness mode movwf mode goto mode_select

;full on led_full bsf GPIO, pwm movlw 0x0F call delay ;used as debounce call bounce btfss flag, new_mode goto led_full goto mode_select

;high brightness routine led_high bsf GPIO, pwm ;turn on LED(s) for a set time movlw led_hi_on call delay bcf GPIO, pwm ;turn off LED(s) fo a set time movf led_hi_off, w call delay call bounce btfss flag, new_mode goto led_high goto mode_select ;medium-high brightness routine led_medhi bsf GPIO, pwm ;turn on LED(s) for a set time movlw led_medhi_on call delay bcf GPIO, pwm ;turn off LED(s) fo a set time movf led_medhi_off, w call delay call bounce btfss flag, new_mode goto led_medhi goto mode_select ;medium brightness routine

00016R1.asm Source Code

TABLE C-1: 00016R1.ASM (CONTINUED)

led_med bsf GPIO, pwm ;turn on LED(s) for a set time movlw led_med_on call delay bcf GPIO, pwm ;turn off LED(s) fo a set time movf led_med_off, w call delay call bounce btfss flag, new_mode goto led_med goto mode_select

;low brightness routine led_low bsf GPIO, pwm ;turn on LED(s) for a set time movlw led_low_on call delay bcf GPIO, pwm ;turn off LED(s) for a set time movf led_low_off, w call delay call bounce btfss flag, new_mode goto led_low goto mode_select

;led off led_off movlw 0x20 call delay bcf GPIO, pwm ;turn off LED(s) movf GPIO, w ;read port before entering sleep mode sleep

;delay loop for on and off time delay movwf counter ; Delay = (3 + (3 * counter) + 2) Tcy loop decfsz counter, f goto loop retlw 0x00

;check for button press bounce btfss GPIO, button ; Is Button Depressed? goto bounce1 ; Yes, go to “bounce1” bsf flag, timer_ena ; No, allow timer to start clrf debounce ; no user entry, reset debounce timer retlw 0x00 ; bounce1 btfss flag, timer_ena retlw 0x00 ;do not increment as we have not seen the debounce released yet incfsz debounce, f ;inc debounce timer retlw 0x00 ;not yet bsf flag, new_mode incf mode, f ;a valid press has been detected bcf flag, timer_ena ;prevent timer from incrementing to prevent cycling though modes by holding debounce bounce00 retlw 0x00

end

NOTES:

00016R1.asm Source Code

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Microchip: MCP1252DM-BKLT

Microchip Technology MCP1252 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Preface

Chapter 1. Product Overview

1.1 INTRODUCTION

1.2 WHAT IS THE MCP1252 CHARGE PUMP BACKLIGHT LED DEMO BOARD?

1.3 WHAT THE MCP1252 CHARGE PUMP BACKLIGHT LED DEM O BOARD KIT INCLUDES

Chapter 2. Installation and Operation

2.1 INTRODUCTION

2.2 FEATURES

2.3 GETTING STARTED

Appendix A. Schematic and Layouts

A.1 INTRODUCTION

Appendix B. Bill-Of-Materials (BOM)

Appendix C. 00016R1.asm Source Code

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