hardware essentials

[Rich L]

Hello and thank you for your video presentation about processing audio on the teensy. I'm trying to round up hardware and noticed that the 3.2 is out of stock. Is it possible to use the 4.0 interchangeably as long as I keep input at 3.3V and below?

Also, I'm assuming that the potentiometers in the Hackaday8292
workshop are 10K

[MichaelMeissner]

Hello and thank you for your video presentation about processing audio on the teensy. I'm trying to round up hardware and noticed that the 3.2 is out of stock. Is it possible to use the 4.0 interchangeably as long as I keep input at 3.3V and below?

Also, I'm assuming that the potentiometers in the Hackaday8292
workshop are 10K

Note, the pinout for the Teensy 4.0 is different than 3.2 WRT to the audio pins and with the SPI/SD card pins. So you might have to adjust some of the sample programs. Unfortunately, I don't think the example programs have comments of what to modify. As I recall, it was mostly the programs that read from the SD card. For example, Part_1_03_Playing Music has:

// Use these with the Teensy Audio Shield
#define SDCARD_CS_PIN    10
#define SDCARD_MOSI_PIN  7
#define SDCARD_SCK_PIN   14

// Use these with the Teensy 3.5 & 3.6 SD card
//#define SDCARD_CS_PIN    BUILTIN_SDCARD
//#define SDCARD_MOSI_PIN  11  // not actually used
//#define SDCARD_SCK_PIN   13  // not actually used

For the Teensy 4.0 you would want:

// Use these with the Teensy Audio Shield
//#define SDCARD_CS_PIN    10
//#define SDCARD_MOSI_PIN  7
//#define SDCARD_SCK_PIN   14

// Use these with the Teensy 3.5 & 3.6 SD card
//#define SDCARD_CS_PIN    BUILTIN_SDCARD
//#define SDCARD_MOSI_PIN  11  // not actually used
//#define SDCARD_SCK_PIN   13  // not actually used

// Use these with the Teensy 4.0 or 4.1 using the SD card in the audio adapter
#define SDCARD_CS_PIN 10
#define SDCARD_MOSI_PIN 11
#define SDCARD_SCK_PIN 13

// Use these with the Teensy 4.1 using the SD card on the Teensy 4.1
//#define SDCARD_CS_PIN BUILTIN_SDCARD
//#define SDCARD_MOSI_PIN 11
//#define SDCARD_SCK_PIN 13

Also programs that write to the DAC (digital to analog converter) won't work on the Teensy 4.0 since it doesn't have a DAC (i.e. sampleplayer).

[PaulStoffregen]

In the audio tutorial material, almost all of it works if you use Teensy 4.0 and the Rev D or D2 audio shield (the one meant for Teensy 4.0).

https://www.pjrc.com/store/audio_tutorial_kit.html

As far as I know, the 2 exceptions are the stuff about blinking the orange LED while playing files (in part 1-5) because pin 13 is used for the SD card clock signal (using pinMode takes away control of that pin from the SD library) and the very last part about connecting a display to visualize the peak meter. That display part can work, but different pins are needed, as the pins shown are specific to Teensy 3.x.

[Rich L]

thanks for your response. I've got a 4.0 coming from 3d maker world before reading this post so it should serve to get me going with the use of the various tools and some coding. Is there a DAC on any of the readily available units that will play samples? or do I just pay the 192 from tinkershere?

[Rich L]

thank you so much for the info. I will start rounding up components

[PaulStoffregen]

Rev D2 audio shields are in stock. They shipped to most distributors this week. Most should have it in stock soon.

If you just want to get sound output, MQS is probably your best option. It's basically PWM with some special noise shaping features, so you get pretty good sound quality but just using a resistor & capacitor to low pass filter away the PWM (which is 352 kHz).

[Rich L]

Ok so if I'm understanding you correctly the sample playing ability exists on 4.0 as soon as the audio shield is added since the ADC and DAC capability is provided by the shield?

[PaulStoffregen]

Quick update, Teensyduino 1.58 has been released, with all the audio library tutorial examples compatible with Teensy 4.0.

The 31 page PDF tutorial has also been fully updated for Teensy 4.0, and all screenshots updated for Arduino 2.0.4.

https://www.pjrc.com/store/audio_tutorial_kit.html