Let's talk of possible new accessory boards

DrM said:
Should add high performance DAC (also, not audio focused).

High performance (probably at least 16 bits up to 20 bits, and 1MSPS) means you also need some analog circuitry on the board.

For range it should probably be 0V to 4V. So add an LDO, voltage ref and one of those small negative voltage ICs.

To really get performance close to 16 bits (or 20 bits) requires a pretty detailed design effort. But we can certainly do that.

On the other hand, there are cheap 16 bit boards. They seem to be just a bare ADC, they are slow (under 1KSPS) and actual performance could be 8 to 10 bits with the noise. But they sell for $6.

Are there enough customers for a board that really does give 16 bit performance, at 1MSPS? And would they buy it if it costs say.. $60?


I have a few designs that go futher, +/-4V range, very high impedance, 16 bits at 1MSPS. It is posted to github, and it is fantastically useful for a lab. But I am not aware of it getting a lot of traffic. I know that there are many people who use cheap usb modules and dont really appreciate the difference.
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For those who are interested, here is the github. The CCD boards (Hamamatsu and Toshiba) , instrumentation input have all been built.

https://github.com/drmcnelson

I am thinking to build the photon tagging system next. That would enable researchers anywhere to be able to do fluorescent lifetime studies. A sponsor for parts would help.
 
The project I am working on now has become something of a Teensy 4.1 motherboard. Specialized for what I need, but a generalized one might be useful in several ways. Teensy 4.1 has a large number of IO, but a single accessory could preclude using any others. So why not make an accessory that permits multiple accessories without requiring jumper wires.

Basically what I'm describing could be as simple as a PCB with header locations (with or without headers pre-soldered, but ideally not) positioned and organized to permit a Teensy and several accessory boards to be attached. Not a typical breakout board. Not an Arduino form factor. Instead, header location(s) for specific functions like I2C. And one for WiFi/Ethernet. One for Power/Li battery management. One for Qwiic connectors. And so on. Maybe some headers are incompatible for use at the same time, but users can decide what accessory mix they want.

Some possible benefits:
  • As a simple PCB with no components, it would be CHEAP. More than one version is possible if there is uncertainty what would be the ideal board design.
  • The benefit for Sparkfun would be an increased compatibility with existing accessories and maybe make development of a new accessory less dependent on the existing pin-out or form factor of the current Teensy. i.e. A board each for T4, T4.1, and eventually T5. And one for Arduino Nano? ESP? RPI Pico? Micromod?
  • Simple system development for some users. Instead of having to simultaneously run wires correctly for power and IO AND find code snippets to work with that accessory hooked up that way, online instructions and code snippets can include comments that indicate how to just plug and go.
  • A more advance board could include some simple components. i.e. USB-C port for power and power management/battery charge chip. Level shifters?
  • People could design custom boards derived from the base PCB design with some confidence on performance and accessory compatibility. My use case is a good example: I use OctoWS2811, level shifters, and an RTC with battery, but need these functions physically in particular locations. Intial prototypes with a standard board permitting all of these as plug in accessories would have been great (jumper wires worked, but was chaotic). Then leveraging the standard board and accessory designs, I could have created a production board that fits my particular use case much faster.
As for particular accessories, I would love to see:
  1. USB-C power with power/charging management chip + Lipo battery connector
  2. 802.11ah Wifi HaLow module
 
Let's talk about a possible CAN bus shield. So far on this thread I see 4 message:
  1. "arduino mega adapter for the t4x with can/canfd/qwiic", msg #3
  2. "CAN Backpack", msg #41
  3. "CAN, with selectable 120ohms termination, for CANOPEN", msg #50
  4. "Another vote for CAN Bus", msg #75
I have some thoughts and specific questions, but as usual I'd like to start with an open-ended question rather than injecting my own bias. If you use CAN or have any interest, now is the moment to tell me how you think a CAN accessory board should look!
 
PaulStoffregen said:
I have some thoughts and specific questions, but as usual I'd like to start with an open-ended question rather than injecting my own bias. If you use CAN or have any interest, now is the moment to tell me how you think a CAN accessory board should look!
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Personally I use Can/CanFD on and off not constantly. Going to assume the shield will sit on lop of the T4 - maybe. I know @skpang has a bunch of boards that support teensy and CAN. This one was interesting. https://www.skpang.co.uk/collections/can-bus-boards/products/can-bus-featherwing-for-esp32

Think there are a several ways to go with this not sure which is the best.
 
@PaulStoffregen

Sorry, probably not much help here. I have never used Can, did buy a couple of adapters for them once to maybe help debug an issue.
Also shield for what? T4, T4.1, MMOD? As for form factor, good question, especially if you are going to do several
and maybe try stack them on each other?

Ones that I more likely would play with:

QWIIC: I agree with @mjs513, I have now played around with several different boards, by Sparkfun, Adafruit, and Arduino that have Qwiic
connectors, and I use them when they are available.

Display: Maybe a better version of Teensy View, maybe a color display like a small ST77xx, maybe small led matrix...

Voltage setup: For example, VR/switcher that allows 2s, 2s Lippo? battery charger, clock backup power...

wireless: Wifi, or LoRa, etc. (Wish list on WiFi, is if somehow you could program the teensy over it, but guessing that is more problematic)

Camera: ..

Or some combinations, for example Arduino has the Portenta H7 and they have the Vision Shield, which comes in couple of configurations.
Current one comes with HM360 camera, with either Ethernet or LoRa connections, plus a few other things.

Will be interesting to see what you come up with.
 
I would say it has to be something that absolutely requires the speed of the Teensy.
You can find pretty much everything you need in terms of boards on the market—but not necessarily for the Teensy. That's not so important, though. You can still use them.

A useful board should take advantage of the high single-core speed—still a unique feature of the Teensy. That's the main reason why I would still buy a Teensy today. What exactly? I'm at a loss. It should be something that isn't available for other boards (or is too expensive?).

It's definitely not CAN. Besides, there are only a few use cases for it in the maker world.

Or, maybe something that uses the crazy number of serial ports(?) – another feature that almost only Teensy offers (and which, even after many years, I still wonder what all the serials are good for – never needed more than one - but hey, there seem to be people who need it. That's fine.)
 
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BriComp said:
Anyone interested in an adaptor board to achieve this (pic shown below).
It would be a board to accept a Teensy 4.0 and an ESP32C3 Super Mini with the relevant pins routed together.
The 5V pins would be commoned, this would mean that the pair could be powered by the ESP32 C socket.
Serial ports would be connected together, probably to Teensy RX2/TX2.
Also SPI ports could be linked.
Let me know what you think.

View attachment 37821
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Yes, I had already built something like that for the ESP8266 back then. However, I couldn't find any use cases for it. It's also tedious to develop for two controllers at the same time. It's easier to just use a fast ESP32, multi-core, without Teensy.

But the C3 is also my favorite board at the moment. Good choice :) With the same (RISCV) MHz, it's absolutely on par with an ARM, has enough memory, and instead of a display, you just use a web interface, with an exorbitant wall-sized resolution if necessary. for 2.50$.

No, an add-on should be something special – not just run-of-the-mill stuff.
 
Coming back to audio, Teensy is about the only platform that does multi-channel audio well. As I said earlier, my updated 8x8/16x16 audio board is open source hardware and software, and I'd be happy for Sparkfun to manufacture boards based on that design.
 
I've thought about it again, and I believe a really fast board with super-fast ADCs and DACs would open up new possibilities that are not really feasible with other run-of-the-mill microcontrollers. You could tinker with Doppler systems or other interesting physical effects. That would at least be one area that is underrepresented.
 
Mcu32 said:
I've thought about it again, and I believe a really fast board with super-fast ADCs and DACs would open up new possibilities that are not really feasible with other run-of-the-mill microcontrollers. You could tinker with Doppler systems or other interesting physical effects. That would at least be one area that is underrepresented.
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How fast would be "super-fast"? I have a USB solution already that gives me 3x 24MHz 8-bit DACs (based on https://github.com/osmocom/osmo-fl2k)
 
jmarsh said:
How fast would be "super-fast"?
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I'm only interested in ADC.
Here is an example I think professional developper can do better.
Attached is a picture of a high performing Acoustic data acquisition system (Custom stereo piezo preamp + custom ADC +Teensy4.1 capable of acquiring stereo data at 384 kHz).


20240421_175751_s.jpg


Issues encountered with such a system:
- noise 'free' power supply for preamps and ADC (typical piezo signal of a hydrophone are < 1uV), rotating T4.1 by 180° removing SD card away from ADC helped a lot, but still the power draw while writing to disk is visible in the data.
- RTC of Teensy is far too power hungry (ended up adding a RV3028)
- power consumption is too high, could be lowered if SDIO could have been used as SPI device.
(Yes SPI decices can consume less power, as deselect the device reduced (at least for my disks) the consumption. SDIO is always on.

So, yes a high performing ADC board with excellent power filtering would be something I'm looking for.
 
I've used the Teensy 4.0 w/ Audio Board to make drum machines, effects pedals and simple synths. On a recent drum machine design, I ended up using 24 pots, 16 step switches and 16 indicator LEDs.

I love the idea of adding multiplexers. Perhaps shift registers for lots of LEDs would be helpful for those building synths. Maybe a 1/8" line-in or instrument level input in addition to the 1/8" output would be nice, too.

If the battery idea was added as well, it would be very easy to make a Korg Volca or Teenage Engineering Pocket Operator style-device.
 
WMXZ said:
I'm only interested in ADC.
Here is an example I think professional developper can do better.
Attached is a picture of a high performing Acoustic data acquisition system (Custom stereo piezo preamp + custom ADC +Teensy4.1 capable of acquiring stereo data at 384 kHz).


View attachment 38607

Issues encountered with such a system:
- noise 'free' power supply for preamps and ADC (typical piezo signal of a hydrophone are < 1uV), rotating T4.1 by 180° removing SD card away from ADC helped a lot, but still the power draw while writing to disk is visible in the data.
- RTC of Teensy is far too power hungry (ended up adding a RV3028)
- power consumption is too high, could be lowered if SDIO could have been used as SPI device.
(Yes SPI decices can consume less power, as deselect the device reduced (at least for my disks) the consumption. SDIO is always on.

So, yes a high performing ADC board with excellent power filtering would be something I'm looking for.
Click to expand...
Okay, it looks like two boards are needed :)
One with high-speed ADC (as fast as reliably feasible).
And the other with low-noise ADC, pre-amps, and > 16 bits.

There's nothing like that on ALIExpress either—which is basically a good thing if PJRC wants to sell it.

@WMXZ: Have you considered using an extra voltage regulator on your board?
 
Mcu32 said:
Have you considered using an extra voltage regulator on your board?
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Oh, yes. I have now detached the ADC and Preamp as seperate boards and have an LDO on the ADC board, and use as 5V source the USB-Host power, which has an own 100uF capacitor. For my application (underwater autonous recorder) the available space is rather limited. So everything is dangerasly close.
I only wanted to give an example where I would use a T4.1.
A scaled down version (single channel 96 kHz) with seperated ADC and Preamp board used a RP2050 Feather from Adafruit, as it consumes much less than T4.1 (at the lowest possible MPU clock).
Anyhow, A well designed high speed ADC board for ultrasonic sound (>16-18 bit) with small form factor would be a great help these type of application.
 
I don't recall if I've replied to this before. For various reasons, I haven't been doing much with micro processors recently, but some thoughts on some useful boards:

When I laid out prototype boards, some of the things that I put into the layout for 4.1 boards:
  • Two Spi layouts, typically I do 8-12 pins:
    • Adjustable power (default to 3.3v, optional VIN)
    • Pin for background light (default to 3.3v, can be changed via dip switch & pin)
    • Ground of course
    • SCLK (pin 13 for SPI0, pin 27/A13 for SPI1)
    • MISO (pin 12 for SPI0, default to pin 1 for SPI1, optional for pin 39/A15)
    • MOSI (pin 11 for SPI0, pin 26/A12 for SPI1)
    • D/C (default pin 9 for SPI0, default pin 24/A10 for SPI1, can be changed via dip switch & pin)
    • Reset (default pin 5 for SPI0, default pin 25/A11 for SPI1, can be changed via dip switch & pin)
    • CS0 (default pin 22/A8 for SPI0, default pin 0 for SPI1, can be changed via dip switch & pin)
    • CS1 (default pin 10 for SPI0, default pin 30 for SPI1, can be changed via dip switch & pin)
    • 2 GPIO pins
    • In the past, I used my own ordering, recently, I've been laying things out so I can attach the Adafruit Eyespi breakout board, which has one row of: VIN, Lite, GND, SCLK, MOSI, MISO, D/C, Reset, and CS0, and another row of CS1 (for SD card), CS2 (for Memory), CS3 (for touch screen select), SCL/SDA for I2C (I usually use I2C0 for both SPI layouts), Interrupt pin, Busy pin, and 2 GPIO pins.
  • Several UARTs (GND, 3.3v, RX/TX, and sometimes extra pins for RTS/CTS). I don't use UARTs as much, and it varies which I bring out.
    • RX1/TX1 is the universal UART for all Teensies, but it does conflict with the defaults for SPI1.
    • RX2/TX2 and RX5/TX5 both conflicts with I2S1.
    • I use the pins for RX3/TX3 for POTs by default (to allow Teensy 3.2 and 4.0 pinouts), but RX3/TX3 is useful if you want to use S/PDIF.
    • RX4/TX4 conflicts with the 2nd I2C port.
    • RX6/TX6 conflicts with the 3rd I2C port.
    • RX7/TX7 and RX8/TX8 are available.
  • I lay out the main I2C, with an option for adding pull-up resistors. I lay it out to I can attach the Sparkfun 0.1" pins to QWIIC boards. For the 0.1" pins, I usually add a 5th pin for the I2C devices that provide an interrupt. I don't think I've ever used the 2nd or 3rd I2C buses, but I suspect people do. Of course with a custom board, I would expect to have at least one QWIIC connection directly.
  • Layouts for both I2S1 and I2S2. I don't think I've ever used I2S2 except for testing, but it can be useful to provide a pinout for it.
  • 4 pins level shifted to VIN for use with Neopixels and Dotstars, I usually lay these out as Vin, Ground, Pin1, Pin2, Ground, and Vin, so that I can either have 2 sets of Neopixels with 3 pins, or 1 set of Dotstars with 4 pins. For historical reasons, I usually use pin 17/A3 as the first neopixel pin, and pin 2 for the second. I have used pins 36 and 37 for pins 3 and 4.
  • Recently, I have laid out pins 38-41 so I can attach a resistor, to allow for attachment of Noods (with a ground pin adjacent to the resistor output).
  • I lay out 3 pins to do either analog input or PWM output. I use pins 14/A0, 15/A1, and 16/A2. I lay it out as 4 pins (Ground, Data, 3.3v, and Ground). The intention is the Ground, Data, 3.3v can be used for attaching a POT directly, while Data, 3.3v, and Ground ordering is often used for PWMs).
  • I usually lay out one button for a momentary push button (usually pin 3)
  • I usually lay out one button to use with a dip switch (usually pin 4)
  • I usually lay things out so I can attach a JST port for battery, and have it charge the battery from VIN.
  • On the Teensy 4.1, it would be useful to have the 2nd USB port with standard pinouts.
  • On the Teensy 4.1, it might be nice to have the the ethernet brought out to a RJ45 jack (with the usual ethernet shield stuff).
  • On the Teensy 4.1, it would be useful to bring out the on/off pin so a momentary push button can be set up.
  • On the Teensy 4.1, it might be useful to bring out the real time clock power pin to a coin cell holder.
  • On the Teensy 4.1, it might be useful to bring out a USB C connection in addition to the historic USB micro B.
BTW, I have a google spreadsheet that lists many of my layouts over time (most just theoretical), based on specific prototype boards:
 
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Another thing would be a Teensy 4.0/4.1 version of both prop shields (though it would be nice if the 4 pins on each end are lined up for 0.1" spacing). Obviously there would need to be changes, such as incorporating an I2S interface for sound, perhaps using PT8211 instead of the more complex audio used in the audio shield.

Perhaps use the Adafruit prop-maker featherwing for inspiration. Useful parts include:
  • 3 port JST plug for neopixels
  • 3 MOSFIT ports for attaching 3W leds or higher power PWMs
  • Triple-Axis Accelerometer with Tap Detection
  • Class D audio amplifier
  • Breakouts plus strain-relief hole for the enable pin and ground (i.e. on/off pins in both Teensy 4.0 and 4.1)
  • Breakouts plus strain-relief holes for an external switch pin and ground
  • And for Teensy, adding JST power plug with automatic charging like the Teensy featherwing board has
 
I'd like, for doing handhelds..
• Very small. Smallest possible.
• Teensy sits on top upside down. So I can wire to anything.
• Teensy's USB is close to end so you can get to it through the case.
• Reset hole in board because.. Reset.
• Lipo charging from USB.
• Pack the charger under the teensy.
• Bus for.. Power, ground, 3.3V, I2C, SPI common. No chip select or resets lines. Only shared things. Maybe 3..4 rows?
• Only have pins for the necessary things. Most are not connected. I can solder to them as needed. (Being upside down)
• 2..3 screw holes to attach (2mm screws)
 
jim lee said:
I'd like, for doing handhelds..
• Very small. Smallest possible.
• Teensy sits on top upside down. So I can wire to anything.
• Teensy's USB is close to end so you can get to it through the case.
• Reset hole in board because.. Reset.
• Lipo charging from USB.
• Pack the charger under the teensy.
• Bus for.. Power, ground, 3.3V, I2C, SPI common. No chip select or resets lines. Only shared things. Maybe 3..4 rows?
• Only have pins for the necessary things. Most are not connected. I can solder to them as needed. (Being upside down)
• 2..3 screw holes to attach (2mm screws)
Click to expand...
A pre-designed board would be great, but if you use the Teensy 4.0, consider combining the following from Adafruit:
What the feather adapter gives you is a JST plug and a recharger from USB. You do not have to modify the Teensy to separate the VIN and VUSB pins (i.e. if there is power on the VIN pin, it will recharge the LIPO battery, if there is no power, the battery will be connected to VIN).

One of the things I like about the feather adapter is the JST plug is firmly mounted. If I solder a normal JST plug with 2-4 pins to a prototype board, repeated insertion and removal of the JST battery plug can weaken the solder connection of the 2-4 pins.

In addition, the adapter gives the mounting holes to use the Adafruit featherwing shields. The featherwing proto board gives you 5 3.3v/gnd pin rows, with additional pins before/after power/ground.

Normally you might use stacking headers to allow the Teensy and featherwing boards to be removed, but you don't have to use stacking headers, if height is an issue.

Given Adafruit has announced they will not be able to sell Teensys after their existing stock is depleted, I assume they probably will not make any new Feather adapters. So, you might want to order now while they have stock.

You can also use the Teensy 4.1, but you would have to mount the Teensy 4.1 underneath the feather adapter, or make it taller, since the JST plug for the battery and lipo charger are positioned behind the Teensy.
 
I'm not sure whether the umpteenth variant of the same hardware is really necessary (or the hundredth CAN/I2C/SPI/serial/Battery/audio interface extension).

Something new would be refreshing and also attract new users.
 
For me I just want to make it easier to hook multiple things to the Teensy. Hence the bus. Typically battery powered, so I need a charger. Somewhere to hook an on/off switch. Small as possible. Anything else I can add to myself. Typcially don't use any connectors. Except possibly the battery one. I'd like to loose that.

For eample a current project I'm working on is a wrist device for boating. Speed, depth, COG, kinda' thing. Tiny tiny tiny.

-jim lee
 
MichaelMeissner said:
Another thing would be a Teensy 4.0/4.1 version of both prop shields (though it would be nice if the 4 pins on each end are lined up for 0.1" spacing). Obviously there would need to be changes, such as incorporating an I2S interface for sound, perhaps using PT8211 instead of the more complex audio used in the audio shield.

Perhaps use the Adafruit prop-maker featherwing for inspiration. Useful parts include:
  • 3 port JST plug for neopixels
  • 3 MOSFIT ports for attaching 3W leds or higher power PWMs
  • Triple-Axis Accelerometer with Tap Detection
  • Class D audio amplifier
  • Breakouts plus strain-relief hole for the enable pin and ground (i.e. on/off pins in both Teensy 4.0 and 4.1)
  • Breakouts plus strain-relief holes for an external switch pin and ground
  • And for Teensy, adding JST power plug with automatic charging like the Teensy featherwing board has
Click to expand...
If accel is planned, please use ISM330DHCX. I think it has the best specs for small SMD at the moment.
I use it with Pi Zero 2W

Is CSI (Camera Serial Interface) ribbon connector in the realm of possibility?
 

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