Troubleshooting “arecord” Issues with ReSpeaker 2-Mic Pi HAT on Raspberry Pi

At revWhiteShadow, we understand the frustration of hardware integration, especially when tutorials don’t quite align with your specific setup. This guide, brought to you by revWhiteShadow, aims to resolve the common “arecord can’t find the right device?” error encountered when using the ReSpeaker 2-Mic Pi HAT on a Raspberry Pi. This article builds on the official Seeed Studio documentation and provides a comprehensive approach to diagnosing and fixing the issue.

Understanding the Problem: Device Mapping in ALSA

The Advanced Linux Sound Architecture (ALSA) manages audio devices in Linux. When you run arecord or aplay, you need to specify which device to use. The -Dhw:X flag tells ALSA to use a specific hardware device, where X is the card number.

The core issue is that the card and device numbers in the tutorial (typically hw:1) may not match your system’s configuration, as revealed by your aplay -l and arecord -l output.

Step-by-Step Solution: Identifying and Using the Correct Device

We will now go through several ways to resolve this issue.

1. Confirming Device Recognition:

Your provided output clearly shows that the ReSpeaker 2-Mic Pi HAT is recognized as card 1: seeed2micvoicec. The device is device 0. Therefore, the correct ALSA identifier should be hw:1,0. However, let’s verify everything step by step.

2. Testing Basic Audio Capture and Playback:

Let’s start with the most basic test. Using the hw:1,0 parameters, execute:

arecord -f cd -D hw:1,0 -t wav -d 5 test.wav

This command does the following:

arecord: The audio recording utility.
-f cd: Specifies CD-quality audio (44.1 kHz sample rate, 16-bit).
-D hw:1,0: Tells arecord to use the ReSpeaker 2-Mic Pi HAT (card 1, device 0).
-t wav: Specifies the WAV file format.
-d 5: Records for 5 seconds.
test.wav: The name of the output file.

After recording, play the file using:

aplay -D hw:1,0 test.wav

If you hear the recording, the basic hardware is functioning correctly. If you still don’t hear anything, proceed to the next steps.

3. Addressing Potential Volume Issues:

Sometimes, the input or output volume might be set to zero. Use the alsamixer tool to check and adjust the volume levels:

alsamixer -c 1

-c 1: Specifies card 1 (your ReSpeaker HAT).

Within alsamixer, use the arrow keys to navigate through the different controls (Capture, Playback, etc.). Press M to unmute a control (if it’s muted - indicated by “MM”). Use the up and down arrow keys to adjust the volume levels. Ensure that the “Capture” level is reasonably high and that it is not muted. Press Esc to exit alsamixer.

4. Advanced ALSA Configuration: Creating a `.asoundrc` File (if necessary)

In some cases, you might need a more fine-grained control over ALSA’s behavior. This is achieved through the .asoundrc file in your user’s home directory.

4.1. Checking for an Existing .asoundrc File:

First, check if you already have a .asoundrc file:

ls -a ~ | grep .asoundrc

If a file is listed, back it up before making any changes:

cp ~/.asoundrc ~/.asoundrc.bak

4.2. Creating or Modifying the .asoundrc File:

Use a text editor (like nano) to create or modify the .asoundrc file:

nano ~/.asoundrc

4.3. Configuration Contents:

Add the following configuration to the .asoundrc file:

pcm.!default {
    type asym
    playback.pcm {
        type plug
        slave.pcm "hw:0,0" # Replace hw:0,0 with your desired playback device if needed
    }
    capture.pcm {
        type plug
        slave.pcm "hw:1,0"  # ReSpeaker 2-Mic HAT for recording
    }
}

ctl.!default {
    card 0 # Change to card 1 if you want the respeaker hat to be the default
}

Explanation:

pcm.!default: Defines the default PCM (Pulse-Code Modulation) device. The ! indicates that this overrides any existing default.
type asym: Specifies an asymmetric device, meaning separate devices for playback and capture.
playback.pcm: Defines the playback (output) device.
- type plug: Enables automatic sample rate conversion, if needed.
- slave.pcm "hw:0,0": Specifies the hardware device to use for playback. In this example, it’s set to the default Raspberry Pi audio output (hw:0,0). Important: If you prefer to play audio via the ReSpeaker HAT (if it supports playback and you have speakers connected to it*), change this to hw:1,0.
capture.pcm: Defines the capture (input) device.
- type plug: Enables automatic sample rate conversion.
- slave.pcm "hw:1,0": Specifies the ReSpeaker 2-Mic HAT (hw:1,0) for recording.
ctl.!default: Defines the default control device (for volume adjustments, etc.).
- card 0: Specifies card 0 to be the default. Change to card 1 if you want the respeaker hat to be the default device.

Save the file (Ctrl+X, Y, Enter in nano).

4.4. Testing after .asoundrc Modification:

After modifying the .asoundrc file, restart ALSA or reboot your Raspberry Pi:

sudo alsa force-reload

Or:

sudo reboot

Then, try the original command again:

arecord -f cd -Dhw:1,0 | aplay -Dhw:1,0

If this now works, the .asoundrc configuration has successfully redirected arecord and aplay to the correct device.

5. Troubleshooting Specific Errors

“arecord: device_list:274: no soundcards found…”: This usually indicates that the ReSpeaker 2-Mic Pi HAT is not being detected by ALSA. Double-check that the HAT is securely connected to the Raspberry Pi. Also check the seeed-voicecard driver installation (see step 6).
“aplay: device_list:274: no soundcards found…”: Similar to the arecord error, this suggests that aplay cannot find any soundcards. It could also indicate an issue with the playback device specified in .asoundrc (if you’re using it).

6. Re-installing the seeed-voicecard driver

Sometimes the installation process for the seeed-voicecard drivers could fail, this will lead to ALSA not properly recognizing the hardware card. To avoid this potential issue, we should reinstall the driver:

cd seeed-voicecard
sudo ./install.sh
reboot

If the driver was not properly installed, this should resolve the issue.

7. Power Supply Considerations

The Raspberry Pi, especially with add-on boards like the ReSpeaker HAT, can be sensitive to power fluctuations. Ensure you’re using a high-quality 5V power supply with at least 2.5A (or more) of current capacity. Insufficient power can lead to erratic behavior and device recognition issues.

8. Checking for I2S Conflicts

The ReSpeaker 2-Mic Pi HAT communicates with the Raspberry Pi via the I2S (Inter-IC Sound) bus. Conflicts can arise if other devices are also using the I2S bus.

8.1. Identifying Potential Conflicts

Review any other hardware or software configurations that might be using the I2S bus. For example, if you’ve previously configured an audio DAC or another sound card, it might be interfering.

8.2. Resolving Conflicts (Advanced)

Resolving I2S conflicts often requires advanced configuration and might involve modifying device tree overlays. This is beyond the scope of this basic troubleshooting guide, but resources like the Raspberry Pi forums and the Seeed Studio forums can offer specific solutions based on your hardware setup.

9. Updating Raspberry Pi OS

An outdated operating system can sometimes cause compatibility issues. Make sure your Raspberry Pi OS is up to date:

sudo apt-get update
sudo apt-get upgrade
sudo rpi-update  # Use with caution - can sometimes introduce instability.  Consider skipping if your system is stable.
sudo reboot

10. Alternative Recording and Playback Tools

If you’re still having trouble with arecord and aplay, try alternative audio tools like sox:

sudo apt-get install sox libsox-fmt-all

Then, try recording with sox:

sox -t alsa hw:1,0 recording.wav rate 44100 channels 1

And playing back:

sox recording.wav -t alsa hw:1,0

11. Seek Support from the Community

If you’ve exhausted these troubleshooting steps, don’t hesitate to seek help from the online communities. The Raspberry Pi and Seeed Studio forums are excellent resources. When posting, provide detailed information about your setup, including:

Raspberry Pi model
ReSpeaker 2-Mic Pi HAT version
Operating system version
The exact commands you’re running
The full error messages you’re receiving
The contents of your .asoundrc file (if you’re using one)

Conclusion: Persistence is Key

Troubleshooting audio issues on embedded systems can be challenging, but by systematically working through these steps, you should be able to resolve the “arecord can’t find the right device?” error and get your ReSpeaker 2-Mic Pi HAT working correctly. At revWhiteShadow, we hope this guide has been helpful. Remember to double-check your connections, verify your device mappings, and consult the community resources when needed. Happy audio hacking!

arecord can’t find the right device?

Troubleshooting “arecord” Issues with ReSpeaker 2-Mic Pi HAT on Raspberry Pi #

Understanding the Problem: Device Mapping in ALSA #

Step-by-Step Solution: Identifying and Using the Correct Device #

1. Confirming Device Recognition: #

2. Testing Basic Audio Capture and Playback: #

3. Addressing Potential Volume Issues: #

4. Advanced ALSA Configuration: Creating a .asoundrc File (if necessary) #

5. Troubleshooting Specific Errors #

6. Re-installing the seeed-voicecard driver #

7. Power Supply Considerations #

8. Checking for I2S Conflicts #

8.1. Identifying Potential Conflicts #

8.2. Resolving Conflicts (Advanced) #

9. Updating Raspberry Pi OS #

10. Alternative Recording and Playback Tools #

11. Seek Support from the Community #

Conclusion: Persistence is Key #