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 Jukebox
Information provided to Parallax by: Brian Dalziel
Brian needed something to put next to his bar in the Rec Room. He took 10 months and $1400 worth of equipment to build his own BASIC Stamp® microcontroller controlled Jukebox. The Jukebox has 4 BASIC Stamp modules that control all facets of its operation. Serial communication is used between a pair of BASIC Stamp microcontrollers. One Stamp is dedicated to page-flip control, another is the display driver, another handles music detection processing and interfaces to the CD changer, and one scans the keypad.
 At the front of the Jukebox are 17 servo-driven “pages” which display the song selections and CD artwork, and one BASIC Stamp module is dedicated to the turning of these pages. Seventeen servos were modified by removing their internal wiper boards and physical stops and soldering two wires directly to the motors. Each “page” is driven from the top with a separate servo, and at the bottom of the page’s shaft is a microswitch to sense position.
After a page flip button is pushed on the keypad, the BASIC Stamp microcontroller scans an R/C network connected through the position switches with RCTIME command to find where the pages are “parted.” The BASIC Stamp module then sends a timed pulse of proper polarity to the proper servo via servo control boards, a task which required more than 35 relays.
 The heart of the Jukebox is a 100-changer CD player. The Jukebox buffers and plays up to twenty songs. There are remote controls mounted inside the Jukebox with the IR LED removed and mounted directly to the face of the equipment. Each button on the keypad is paralleled with an optoisolator and connected to a BASIC Stamp module. As songs are input, buffering happens in the BASIC Stamp microcontroller and is written into the EEPROM. Another BASIC Stamp module processes music detection through one pin and a VU board (which also flashes the front jumbo amber LEDs).
As a song ends, the one BASIC Stamp module pulses the other BASIC Stamp microcontrollers to unspool buffered tracks. A Max7219 display driver was used to drive the LED display. Volume control is done from the keypad as well.  To construct the keypad Brian used the 10-key area from a computer keyboard. He then paralleled each button with an output and a common wire. The BASIC Stamp microcontrollers use the BUTTON command to scan keypad for activity.
Photos and specifications of the Jukebox are courtesy of Brian Dalziel
e-mail: bdalziel@core.com. |
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