DDIM16 - Prototype 16 load digital dimmer

Features

• Can drive up to 16 loads, using Croydom SSRs (must be non-zero-cross SSRs, eg D2425-10)
• Load power depends on choice of SSR and heatsinking
• Use of choke in series with load is recommended to reduce EMI.
• RS232 interface, protocol based on Centralite Ambience product, with exclusions and extensions
• RS485 port, which can be configured to be a control port, allowing RS485 control, or can output DMX512 data, allowing external dimmers to be controlled
• Many configurable settings, for example, default fade rate, all-off scene etc
• 99 scenes
• Any load can participate in any scene
• Configurable fade rates, which can be overridden by RS232.
• Maximum fade time is about 27 minutes
• Each load transitions independently to its target level at the rate specified by the last command to that load, so simultaneous level changes of different loads at different fade rates is fully supported
• 16 logical buttons, each with configurable scene call-up and fade rate, addressable by RS232
• 8 hardwired button inputs (of the 16 logical button inputs)
• 8 LED outputs, with on-board current limit resistors. Could be used to drive additional on/off SSRs, or with amplification, a relay or contactor
• All external wiring (except SSR drivers) has an inline filter to reduce rediated EMI
• Uses the proven Artistic Licence AL4016 dimmer driver chip for Crydom control. (nb - load power must be in phase with the power supplied to the control board)
• Troubleshooting LEDs for power, status and DMX512 present.
• Hardware supports MIDI in, intended for MSC applications, but the firmware does not support MSC at present.
• Hardware supports an external TW-523 for integration with X10, but the firmware does not support this feature at present.

Architecture

The dimmer uses a two chip approach:

• A control chip, which accepts RS232 (or RS485, if so configured) commands, accepts button presses, drives output LEDs, and generates DMX512.
• A driver chip, a commercial, preprogrammed PIC, which accepts DMX512 data, and mains zero crossing pulses, and generates timed pulses for phase shift dimming.

Source Code

The source code for this project is available under the GPL ddim16ca.zip

Construction

Schematic: ddim16sa.pdf

PCB Gerbers: ddim16pa.zip

Bill of materials: ddim16ba.txt

Crydom data sheet (offsite link): crydom_cs.pdf

Artistic Licence dimmer chip (offsite link): AL4016

Picture

PCB Overlay