Pololu Robotics & Electronics
Menu
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

Controlling MP3 Trigger with the Maestro

Hello, I am having a little trouble getting the Maestro script to send a command to the MP3 Trigger to play the audio file. I found another thread with a suggestion to set the Trigger to 0 in the Maestro Control Center script to make it play, but that did not work. Any and all help is greatly appreciated! :slight_smile: Here is a picture of my setup in case I did something wrong there. I have the white wire going from the RX on the Trigger board to Port 0 on the Maestro. Thanks again!

Hello.

There are a couple different problems I notice from your picture.

First, it looks like you are not soldering your connections to the MP3 Trigger; you will need to solder them to ensure a good electrical connection. I typically prefer using male or female header pins so you can easily change your connections with the jumper wires.

However, before you solder, it looks like you are also mixing up the connections. There are 2 different options for triggering a track on the MP3 Trigger from a Maestro script.

The first option would be using the trigger inputs on the MP3 Trigger. The 18 input pins on the MP3 Trigger (TRIG01-TRIG18) can be used to trigger specific tracks on the microSD card by driving them low (the MP3 trigger pulls them high by default). To do this from a Maestro channel, you can configure the channel as an Output in the Channel Settings tab of the Maestro Control Center. After that, the “position” of the channel will determine if the channel outputs a high or low signal (the output is low unless the position value is greater than or equal to 1500.00 μs). So, you can use a separate Maestro channel for each trigger input you want to use by connecting the desired Maestro channel to the dedicated trigger input pin on the MP3 Trigger. Please note that you should also have a common ground between the two devices. You can read more about the trigger inputs on the MP3 Trigger under the “Using the Trigger Inputs” section of SparkFun’s MP3 Trigger hookup guide.

The second option is using the MP3 Trigger’s serial interface. This option is only applicable to the Mini Maestro controllers (i.e. not the Micro Maestro since the script commands for sending serial signals do not work with it) and it does not use any of the Maestro’s channels since it uses the UART pins instead. To do this, you would connect the TX pin from the Maestro to the RX pin on the MP3 Trigger, as well as the common ground connection. Jon’s post here has an example of what the script commands would look like to trigger a track, as well as some configuration notes. You can find more information about the MP3 Trigger’s serial commands in the “Serial Control Protocol” section of its hookup guide.

Also, please note that the tracks on your microSD card will need to be named appropriately, as described in the MP3 Trigger hookup guide.

Brandon

Hello, so I rewired it, hopefully it is correct this time? I am still unable to get the Maestro script to trigger the audio files. Are you able to provide me with a sample code to trigger the audio file? Thank you again for your help!

To remove variables while troubleshooting, I recommend just using the sliders in the “Status” tab of the Maestro Control Center to toggle the trigger pin. Please note that you will need to configure your Maestro channel as an “Output” under the “Channel Settings” tab of the Maestro Control Center. After that, when the channel is enabled and the position is less than 1500us, the pin will be driven low, which should trigger the track to play.

However, before you do that, it looks like there are a few potential problems from what I can make out in your picture (although it is hard to see all of the connections at that angle).

  1. It looks like you still might not be soldering your connections to the MP3 Trigger. As I mentioned before, you will need to solder your connections to make a good enough electrical connection to be reliable.

  2. It looks like your connections from the Trigger pins to the Maestro are backwards (i.e. the green wire from the MP3 Trigger should go to one of the ground pins on the Maestro and the yellow/orange wire coming form the TRIG1 pin should go to the Maestro channel’s signal pin). On the MP3 Trigger, the row of pins closest to the edge of the board are all ground pins, and the inner row are the actual triggers.

  3. You didn’t include all of your connections, so it is not clear what you have connected to the audio jack output. Additionally, the problem could be with how you have named the file on your microSD card. However, if fixing the things in #1 and #2 do not correct the problem, you might try taking a step back and testing the MP3 Trigger separately from the Maestro to make sure you can get it working first. You can find some general troubleshooting steps for the MP3 Trigger here, which include some sample audio files that are pre-named with the correct syntax.

Brandon

Hello, so I soldered the wires onto the board and hopefully wired it correctly this time. I also named my audio file 001TEST.mp3 and made sure that it was set as an output on the Maestro software. However, when I move the slider down, it still won’t play the audio. The audio only plays when I hit the physical button on the MP3 Trigger. Thank you for all of your help so far, I really appreciate it!


Thank you for the updated information. Since the file plays when you use the physical button, it sounds like the MP3 Trigger can read the microSD card properly and the file is named correctly. Unfortunately, most of your solder joints look like they are not properly wetting to the board. To ensure a good electrical connection, they should resemble the ones shown in the “Adafruit Guide to Excellent Soldering”. Could you try reworking them and seeing if that helps?

If that does not help, could you post some updated pictures of your soldering as well as a copy of your Maestro settings file? You can save your settings file from the “File” drop-down menu of the Maestro Control Center while the controller is connected.

Brandon