Arduino DMX libraries now also available on Github

 

In the last weeks I got some very valuable feedback and some corrections for the DMXSerial2 library for Arduino from Felicitus and he asked me to put the sources into the GitHub repository.

I am used to work with Subversion and never worked with Git before but everything runs perfectly. I love the way how someone can add merge requests to an existing repository without the need to manage users and roles.

So you can find the library now on:
https://github.com/mathertel/DmxSerial2.

You can download the complete library including the samples by using the “Download ZIP” button on the right-hand side or by using the link
https://github.com/mathertel/DmxSerial2/archive/master.zip

I plan to also leave a copy of the other Arduino libraries there.

Arduino Shield for NRF24L01+

Here is the picture of a brand new Arduino Shield for the NRF24L01 on top of an Arduino UNO:

It’s the first version and it works :-) so I finally soldered a transceiver directly onto it.

Signal layout

The signals for the SPI bus come from the ICSP connector to make it compatible to Arduino boards that do not have the classic ATmega328 (2009, UNO) but use other processor ICs like Leonardo, Mega. Here the MIIS, MOSI and SCK signals are not D12,D11 and D9. Using the ICSP connector is compatible.

The CSN and CE signals can be connected to pin D7 and D8 by using little solder drops on top of the shield that you can see on the right. Using these 2 pins because they do not conflict with other cards I use (Ethernet, SDCard). Initialize the RF24 radio class by using:

RF24 radio(7,8);

If other pins must be used, the 2 solder pads can be kept open and some wires can be used to pass the signals.

The IRQ signal is available on pin D3 the same way, but I don’t use it yet.

The rest of the shield has a permanent breadboard layout for small robust implementations.

In the back you can see another connector for I2C bus that I use to connect other hardware like LCD panels.

Prototypes:

Before I had 2 versions in place that I made. The first one was a “flying” transmitter that was perfect for finding the right pins and setup. The second one is sitting on top of an DMX shield.

See also:

Hints on using NRF24L01+ with Arduino

This is a first version of a NRF24L01 shield, especially the breadboard it not perfect. I ordered more than I need so if you are working on a NRF24L01 project and like to have one – let me know. (first come first serve)

Another DMXSerial example

The DMXSerial library for the Arduino that you can find at http://www.mathertel.de/Arduino/DMXSerial.aspx has only 2 small examples that show the principle functionality of the DMX library:

• DMXSerialRecv implements a 3 channel DMX device on channel 1-3 and sends the data to the PWM output pins 9, 6 and 5.
  It also shows the usage of the DMXSerial.noDataSince method.
• DMXSerialSend implements a 3 channel DMX Controller sending a continuously changing color schema to the channels 1 to 3.
  Here an array of color definition is used and the implementations adjusts the current color smoothly into the next color from the arrays.

Now there is a new example available:

DMXSerialFlow implements a 60 (20*3) channel DMX Controller sending a continuously changing colors schema to the channels 1 to 3.

The calculation of the colors is done by using a hue to rgb converter.

Hue is a number from 0 to 764 that represents one of the colors of a color wheel. With a simple algorithm it is possible to calculate the red,green and blue component of it.

There are some hints inside the code that allows you to make some changes for example the speed of the color changing.

This example was used for testing a wireless 2.4 GHz DMX transceiver that I am working on right now. Stay tuned :-)

Update for the DMXSerial library

There is a significant update for the DMXSerial library on my web site that enables programming DMX devices on ARDUINO MEGA boards and ARDUINO Leonardo boards using the DMXSerial library.

The original library was written for Arduino 2009 and Arduino UNO boards that use the ATmega328 or ATmega168 chip. These chips only have a single Universal Synchronous and Asynchronous serial Receiver and Transmitter (USART) a.k.a. the Serial port in the Arduino environment. The DMXSerial library uses this port for sending or receiving DMX signals.

This conflicts a little bit with the usage of the programming mode the Arduino offers through then USB ports or serial interfaces but it is possible to build compatible DMX shields that don’t interfere with this usage if done right. The DMXShield is an example of this.

Arduino Leonardo

The Arduino Leonardo board uses a chip that has a USB 2.0 port available in addition to the USART. Therefore the “Serial” port is routed through the USB port that behaves like a serial port device and not the built-in USART. If you like to address the real Serial port you have to go with the Serial1.

But if you look at the hardware and the registers directly the USART0 still exists but the definitions for addressing the registers have changed (for example USART_RX_vect is now USART0_RX_vect). Therefore some adjustments had to be done.

With this board you can write debugging information to the Serial port in your sketch for debugging or data exchange purpose. So maybe a DMX diagnostic sketch can profit from that.

Arduino MEGA 2560

When using the chip on the Arduino MEGA 2560 board you have more than one USART available and maybe you wish to use port 1 instead of port 0. This can be done by enabling the definitions for port1 in the library just uncomment the line

#define DMX_USE_PORT1

ATmega8 boards

I added the definitions of boards based on the ATmega8 too for experimental purpose. If you find problems with these boards, leave me a note please.

Thanks to Bob Lynas to support me.

Available

The updated version is available on my site at: http://www.mathertel.de/Arduino/DMXSerial.aspx.

DMX Receiver version 03 is running

I just updated the article on my DMXSpot project.

This picture shows the fist good version of the PCB for building simple LED projects with DMX control. It
contains only the parts needed to receive a DMX signal including the isolation parts known from the DMXShield and 3 MosFets that can drive some amperes of load. That should be enough to control a huge amount of LEDs or some power LEDs.

 

  The schema and the PCB eagle files are available in the download from the article.

Important DMXSerial Library update

Thank to Jonathan L for this brilliant work on fixing some timing conditions with the sending side of the DMXSerial library.

From his comment:

I'm sure the existing timings (81us break) are pretty much fine with almost all DMX inputs, even though the spec says that the transmitted break time needs to be >= 92 us with MAB >= 12 us.   Nonetheless I was motivated to fix it to be as close to 100 us/12us as I could, as this is what is transmitted by most of the commercial DMX units I've seen.

The real issue would be if you ran this on a faster processor, in which case the timings would break when the interrupt service routine became faster than the byte time.  I was running this on 16 MHz Atmega 328.  Most of the ISR is spent doing the long division inside DMXSerialBaud(): I replaced it with a compile-time calculation of the prescaler value, and this results in trashing the last data byte and the break.  You can see the results in attached timing23.png.

Happily all is fixed by the changes, although the code is a bit more complex.

I studied the changes to the routines and I understand h did everything. It's all well commented and I like his programming style too. I loaded it into a project I have done some months ago and it works fine.

I personally haven't used much the sending part of the library. The last projects were lighting systems that are controlled by DMX used the receiving part only and I found it reliable but he fixed a buffer bug in this too.

The DMX spot PCBs finally arrived

After 2 weeks of waiting the first shipment of the PCB board finally arrived.

I can not wait to soldering the parts together.

My first impression is that the arrangement of the components fits well. If I find out that the circuit works as intended, I'll publish the Eagle files on my website.

DMX Spot project

The aim of this project is to build a small PCB board for RGB LED installations and to use the DMX protocol for controlling.

I build this board because I want to have a permanent and robust solution for light installations and I like to release my Arduino board for other projects.

Also, when using a standard Arduino board there are many components built in that are not used at all. For a simple DMX solution the ATMEGA 168 that was used in older Arduino versions is powerful enough and still provides enough memory for complex programs. So all you can find on this board are the minimum components for a 3 channel DMX receiver and the components to drive LEDs with a voltage around 12 volts or higher.

Because I started with an Arduino board many characteristics of the Arduino design remain:

• The processor can be a Atmel ATMEGA168 or ATMEGA328.
• The clock speed is 16 MHz.
• The surrounding elements like the capacitors have the same values.
• The software implementation uses the Arduino environment.
• I can reuse all the source code I have written so far for my Arduino.

The additional parts compared to the Arduino board are the chips of the communication interface that is able to receive DMX signals including an isolation and 3 Mosfet chips for driving LEDs.

The board uses only standard through-hole soldering components allowing an easy building for hobbyists like me.

Here are some pictures of the Arduino assembly and from my first prototype.

There where several problems with the first version so I had to patch some wires and add some components on the back. Not good enough to be published.