Datasheet

ManualsBrandsRockbox ManualsMedia PlayerArchos Recorder 15

his project provides a wired remote

control for certain members of the

Archos family of hard disk-based

Jukebox MP3 players and recorders. Key

features of the design are:

• Low component count and cost.

• Simple construction.

• Compatible with a small enclosure.

• Runs off a single battery.

• Long battery life.

Introduction

Although there are now many different

audio compression technologies available,

MP3 is, without dispute, the most widespread

and best supported of those used for moving

music around on the Internet and for carrying

it with you as you travel. Following on

the heels of small capacity (64-128 MB)

solid-state players that hold about an hour or

two of music, there are now a number of hard

disk-based MP3 players and recorders

available, such as those offered by Archos

(www.archos.com).

While not as robust as the solid-state

players — which have disk sizes up to 20 GB

— these devices can store the equivalent of

300 CDs in MP3 format — even more if you

are prepared to sacrifice sound quality for

greater compression. The good news is that

they are becoming more affordable as the

cost of disk storage continues its downward

trend. While most would agree that they lack

the elegance of products such as the Apple

iPod, the Archos players come with a much

more palatable price tag.

Price is not the only advantage that

Archos can claim over its rivals. Several of the

company’s products have attracted an active

open-source community that is developing

alternative software for them. This software,

called Rockbox (http://rockbox.haxx.se), is

rapidly becoming superior to the standard

software. The Rockbox site also offers lots of

information about the Archos hardware and

ways in which to modify it, either directly or

via pointers to other websites. I’ve upgraded

my 20 GB Jukebox Recorder with a 40 GB

drive, thanks to information available there.

This is a relatively simple upgrade, but

there are more tricky ones to be found if

you like modifying your gadgets and feel

adventurous.

Looking through the mailing list hosted at

the Rockbox site, I found enough information

to be able to design and construct a wired

remote control for my recorder. Archos offers

a remote, but only as a component within a

complete travel kit that also includes a power

adapter, cassette adapter, and headphones —

all of which I already have. Building my own

remote seemed to be a much better option

than paying for things I didn’t need.

MAY 2004

PIC-Based Archos

Remote Control

A Great Use for a Small PIC

UTS &

OLTS

Everything For Electronics

This Month’s

Projects

Archos Remote . . . .44

Digital Project . . . . . 52

The Fuzzball

Rating System

To find out the level

of difficulty for

each of these

projects, turn to

Fuzzball for

the answers.

The scale is from

1-4, with four

Fuzzballs being

the more difficult

or advanced

projects. Just look

for the Fuzzballs in

the opening header.

You’ll also find

information included

in each article on

any special tools

or skills you’ll

need to complete

the project.

Let the

soldering begin!

Project by Steve Russell

Figure 1.

Tip and ring connections.

Summary of content (8 pages)

PAGE 1
Project This Month’s Projects by Steve Russell PIC-Based Archos Remote Control A Great Use for a Small PIC Archos Remote . . . .44 Digital Project . . . . . 52 T The Fuzzball Rating System To find out the level of difficulty for each of these projects, turn to Fuzzball for the answers. The scale is from 1-4, with four Fuzzballs being the more difficult or advanced projects. Just look for the Fuzzballs in the opening header.
PAGE 2
PIC-Based Archos Remote Using the Remote With Your Jukebox The remote control described here should work with all Archos Jukebox Recorder and Jukebox Studio devices (see Sidebar). For convenience, I’ll just say recorder from now on when referring to all supported players and recorders. A stereo headphone jack plug has a tip, ring, and sleeve to provide the connections to the left and right audio signals and the ground reference.
PAGE 3
Project Referring to the schematic in Figure 3, two outputs of the PIC12LC508A (GP4 and 5) drive a 2 x 3 matrix of switches. The switch states are read in using inputs GP0, 1, and 3, which are equipped with weak internal pullups (determined by the device’s configuration bits), so no external resistors are required. These inputs also support “wake on pin change,” which allows the PIC to sleep while waiting for a switch to be pressed. The final output (GP2) drives the serial data to the Archos Jukebox.
PAGE 4
PIC-Based Archos Remote flexible enough commands. to allow additional • Repeatedly sending the volume adjustment commands if the corresponding switches are held down, so that the volume continues to increase or decrease, as required. • Making sure that data is transmitted at the correct rate for the Archos to recognize it. The specification of the ’508A’s internal oscillator timing is not quite as accurate as required for serial communications.
PAGE 5
Project MCU’s pre/post-scaler to the watchdog timer (WDT). When the user presses a switch, *************************************************************************** the ’508A wakes up and, after ‘bitdelay ‘ debouncing the switch, sends the ‘ INPUT: The value in bitadjust is initialized at POR to make the appropriate command to the recorder entire loop starting at nextbit in xmit take exactly 104 instruction before going back to sleep. The WDT is clocks.
PAGE 6
PIC-Based Archos Remote instructions (no operation). These allow the switches to be read accurately and are necessary because the pullup resistor on GP3 is about 10x larger than the pullups on GP0 and GP1, causing a delay before this input accurately reflects the switch status. Once the switches have been debounced, the data read from the switches is converted into a command that is used to determine the necessary action, implemented by a call (actually a goto) to fntable.
PAGE 7
Project Figure 5. The completed remote control. via a link in fntable. Calibration Mode Tools Everything For Electronics NUTS & VOLTS Tools for Construction Construction is straightforward — just make sure you get the ’508A situated the right way.The ceramic capacitors I used were not polarized.Take care in soldering the PIC pins in particular to make sure that no solder bridges are formed. Note that you will need a device programmer to program the PIC12C508A.
PAGE 8
PIC-Based Archos Remote Parts List The parts are all very easily sourced from vendors such as Digi-Key, Newark InOne (formerly Newark Electronics), and Future Electronics.Watch out for minimum quantities of the low power PIC12LC508A. Newark InOne sells single chips. S1-S6 IC1 C1 C2 X1 Be an FCC LICENSED ELECTRONIC TECHNICIAN Learn at home in your spare time. Single-pole, single-throw push to close switch PIC12LC508A microcontroller 0.1 µF ceramic SMD capacitor 10 µF ceramic SMD capacitor Three pole, 3.