RTB_D21

The D21 decoder is a double sided mobile decoder with Next18 (NEM-662) connector. The decoder is designed to integrate into the RTB digital control infrastructure.

See also

• RTB_D16
• RTB_D20

User Guides

• User Guide - DE
• User Guide - EN

The decoder has the following features,

• Next18 (NEM-662) connector
• DCC
  • DCC-A automatic logon
  • DCC-R protocol extension
  • Service Mode Programming
• Railcom
  • Channel 1/2
  • POM, xPOM
  • DYN: Speed, QoS, Track-voltage, Motor-current, AUX-current, Temp, Distance travelled
• Double sided
• Dimension: 15 x 9.5 mm
• 7-20V track voltage
• heartbeat LED
• adjustable max motor current (default 300mA)
• adjustable max AUX current (default 500mA)
• over temp protection
• Function output: LF/LR (dimmable, 1.4kHz) open drain
• Function output: AUX1/AUX2 (dimmable, 1.4kHz) open drain
• Function output: AUX3/AUX4 logic level (3.3V) or ZBCLK/ZBDAT (3.3V)
• Function output: AUX5/AUX6 logic level (3.3V)
• optional external buffer capacitor (max. 1500uF)
• <10mA idle power consumption
• SUSI3 (3.3V logic level)
• Firmware update over main tracks via DCC-R protocol

Hardware

The current PCB layout uses SMD footprints with 0.5mm pitch and 0402 parts. Reflow soldering is recommended.

PCB

• 6-layer PCB, FR4, 15 x 9.5 x 0.8mm (double sided)
• CPU: AVR64DD28
• Motor bridge: DRV8231
• Connector: Next18 (NEM-662)

Kicad

Schematic | Layout | Gerber

Dependency

🟡 Requires my Kicad project library RTB_SamacSys in the same directory tree.

Firmware

Filename structure: { pcb }{ code }{ version }.hex

Example: D21F0001.hex

	Description
pcb	Name of matching hardware (D21)
code	Type of code contained (R=rom, B=bootloader, F=flash, U=bld update, P=UPDI factory code)
version	Release version (####)

Firmware files

Images

top	bottom

YouTube

Some YouTubes to see the D21 motor driver in action.

This project is intended for hobby use only and is distributed in accordance with the Apache License 2.0 agreement.