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Thread: Possible new shields

  1. #1
    Senior Member+ MichaelMeissner's Avatar
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    Possible new shields

    Paul suggested posting shield suggestions here so it doesn't get lost in the future features & pinout thread:


    So I figured to begin the discussion. I'll post my first thought as a reply.

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    Senior Member+ MichaelMeissner's Avatar
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    Cool Hacker's shield

    One thing that I often try to do in my customized prototype boards is to lay things out logically.

    Right now, with the Teensy 4.0 I could imagine having clusters of pins that you can use pre-crimped dupont jumper cables with fixed headers to bring out certain features:


    Or recently, I've been thinking of going with wire connections that latch more securely, such as the common 2x5 shrouded connector or RJ45 (8P8C).

    The idea is when you are working something, you want to treat it as legos. You might decide in a particular project you want some sound, some I2C sensors, and two SPI displays (i.e. uncanny eyes with motion sensors and doing sound effects). Another time you might want to have an USB host. A third time, you might want to use some WS2812B leds, or all of them at the same time.

    And for some things you want VIN output or 3.3v.

    So what kinds of groupings would I want:
    • I2S 1: VIN, 3.3v, ground, pin 23 (MCLK1), pin 21 (BCLK1), pin 20 (LRCLK1), pin 7 (OUT1A), pin 8 (IN1). Possibly pin 32 (OUT1B), pin 9 (OUT1C), and pin 6 (OUT1D).
    • I2C 0: 3.3v, ground, pin 19 (SCL0), pin 18 (SDA0) -- there would be space to solder in the appropriate pull-up resistors for pin 19/18 (for I2C 0, they probably could be permanently attached).
    • SPI 0: VIN, 3.3v, ground, pin 13 (SCK0), pin 11 (MOSI0), pin 12 (MISO0), pin 10 (CS0), plus a few other mounting holes with a second parallel row, that can be used to attach other CS, D/C, reset pins with jumper cables. There should be a place to attach pull-up resistors for the CS/DC/reset pins.
    • SPI 1: VIN, 3.3v, ground, pin 27 (SCK1), pin 26 (MOSI1), pin 1 (MISO1), pin 0 (CS1), plus a few other mounting holes with a second parallel row, that can be used to attach other CS, D/C, reset pins with jumper cables. There should be a place to attach pull-up resistors for the CS/DC/reset pins.
    • At least 2-3 serial connections (3.3v, ground, TX, RX).
    • A micro SD card slot.
    • A USB host mounting slot with the appropriate voltage protection, etc.
    • Bring out VUSB, VIN, and ground next to each other to attach a battery/charger combo, that does not affect the main pins for stacking other shields.
    • I don't use CAN currently, but that too should be brought out.


    Of course the larger you make the board, the more expensive it is going to be. But a larger hacker board might also include:
    • Several groupings with ground, data, 3.3v with the data doubled up. The idea is to be able to attach potentiometers directly to the board, but use a jumper pin to select which analog input pin to use.
    • Several groupings with data, ground, 3.3v, and VIN to allow hooking up servos.
    • A few LEDs (with resistors) that you could plug in random jumper wires to.
    • I2S 2: VIN, 3.3v, ground, pin 33 (MCLK2), pin 4 (BCLK2), pin 3 (LRCLK2), pin 2 (OUT2), and pin 5 (IN2).
    • I2C 1: 3.3v, ground, pin 16 (SCL1), pin 17 (SDA1) -- space to optionally put in the pull-up resistors.
    • I2C 2: 3.3v, ground, pin 24 (SCL2), pin 25 (SDA2) -- space to optionally put in the pull-up resistors.
    • Other Serial, Can ports.
    • One or more built-in 74AHCT125's that allow using WS2812B (neopixel) or APA102 (dotstar) led streams.
    • A few places with momentary buttons that you would attach a pin with a jumper wire.
    • A few places with dip-switches that you can make more permanent selections.
    • Flash memory hooked up to a SPI bus.

  3. #3
    Senior Member+ mjs513's Avatar
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    One of things that I did with most of my breakouts for the t3.5/6 and the T4 was use the Arduino shield concept so I could stack custom shields or already available shields but that has some drawback.

    Recently been thinking of another concept where I have a master board maybe with basic stuff on it like the USB host port power for the T4, etc. then create a connector like the old S100 bus (yes I am showing my age) that you would plug other modules into to suit your needs but wasn't planning on doing this for the T4.0 - thought I would wait for the 1170 (T4x) so other pins would be available. Right now this is just a thought experiment on my part

    As you know any effort like this would be a nice design effort.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by mjs513 View Post
    One of things that I did with most of my breakouts for the t3.5/6 and the T4 was use the Arduino shield concept so I could stack custom shields or already available shields but that has some drawback.

    Recently been thinking of another concept where I have a master board maybe with basic stuff on it like the USB host port power for the T4, etc. then create a connector like the old S100 bus (yes I am showing my age) that you would plug other modules into to suit your needs but wasn't planning on doing this for the T4.0 - thought I would wait for the 1170 (T4x) so other pins would be available. Right now this is just a thought experiment on my part

    As you know any effort like this would be a nice design effort.
    It might be simpler to use the Rasberry Pi 2x20 IDC cable. That is all through hole (0.1" or 2.54mm) spacing, and there are cheap cables, shrouded headers, etc. Though of course there might be an issue if somebody plugs some device meant for a Pi into the bus with different pinouts.

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    Senior Member PaulStoffregen's Avatar
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    At this moment I've considering 3 shields...

    1: Speaker amplifier with I2S input, plus NAND serial flash (64 Mbyte) - similar to the prop shield, but meant for Teensy 4.0, and without the motion sensors.

    2: Microphone and WS2812B 5V buffer

    3: Lipo battery charger & power management (maybe in 2 versions, with 5V boost & Teensy runs from 3.7V)

    So far, what I'm seeing in this thread sounds like breakout boards. Is that right?

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    Senior Member+ mjs513's Avatar
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    That is one possibility, would be simpler for one or 2 modules but if you have a few different ones... Was thinking actually thinking of having the modules plug into themselves then you can daisy chain them to together and actually create a larger board

    Fun times that we live in.

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    Senior Member+ mjs513's Avatar
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    @PaulStoffregen

    That was the approach I was taking. The rationale for that approach was a couple fold was mainly for expandability and customization almost like the Arduino concept of stacking different shields. Which for some use cases is goods

    At the same time of have shields that attach directly to the T4 is good for some use cases as well.

    You might want to check out what @brtaylor did for his Teensy backpacks which isn't a bad idea either: https://forum.pjrc.com/threads/53695-Teensy-Backpacks. His site seems to be offline right now.

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    Senior Member+ mjs513's Avatar
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    Was actually thinking about starting from an initial layout like this:
    Click image for larger version. 

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    It would need some rearranging but its a start. Oh btw the header is for a ili9341/9488 display on SPI.

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    thank you for creating this thread

    personally i would buy a shield / breakout if it meant i could build a project more quickly - the nano breakouts work quite well with a teensy

    i am venturing into my own boards but it is not a quick instant solution

    the suggestions i have are

    ADC shield - allows 4/8 high resolution analogue inputs
    bluetooth/wifi
    5v tolerant pins
    tft screen shield
    maker shield - sd card / accelerometer / some leds, buttons and maybe a simple peizo speaker
    more robust usb connector
    screw connections and female headers
    rugged shield - for harsh environment / overvoltages

    3d printed enclosures


    what are peoples thoughts ?

  10. #10
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by PaulStoffregen View Post
    At this moment I've considering 3 shields...

    1: Speaker amplifier with I2S input, plus NAND serial flash (64 Mbyte) - similar to the prop shield, but meant for Teensy 4.0, and without the motion sensors.

    2: Microphone and WS2812B 5V buffer

    3: Lipo battery charger & power management (maybe in 2 versions, with 5V boost & Teensy runs from 3.7V)

    So far, what I'm seeing in this thread sounds like breakout boards. Is that right?
    Interesting shields, though I probably would prefer one shield with all 3 options.

    I go back and forth as to how to provide battery charging to the Teensy. In the past I've used onehorse's. My problem is it doesn't fit into using other shields because it only occupies a portion of the Teensy volume. I.e. if I mount it on the bottom, the Teensy doesn't sit flat. If I mount it on the top, I can't use other shields. Also the JST connector with only two pins is not very secure when trying to remove batteries. I have to be real careful, not to rip the JST connector off.

    So most recently, I've used the Adafruit feather adapter, which provides a passive charging system (i.e. you don't have to cut the VUSB -> VIN pad). I haven't tried out the Teensy 4.0 on/off switch to see if the Adafruit feather adapter would still charge the battery. If so, that is a plus. But from a prop usability stand point, the feather adapter has the JST connector is very when secured, and there is no problem removing batteries. While being able to mount some of the feature wings is nice, for displays at least, Adafruit misses the boat, in that on the Teensy, you have to mount the feather display underneath the Teensy.

    Presumably the 5v boost version would work with the USB host pads, and bring that out.

    Having the microphone and speakers on two separate boards seems to miss some common cases. Having a microphone and a level shifter allows you to do the displays based on the background sounds, but it misses the case where you might want to do a sound change. I've been noticing the Monster M4SK from Adafruit has a microphone input and speaker output, and it is now getting the initial ability to do vocal changing (i.e. 'dalek' speech). This might be better for the full audio shield, as there are comments that it degrades the performance of the M4 in the M4SK.

    As I've said before, with my brief usage of some of the Adafruit boards, it is so much simpler to have the microprocessor export a removable file system, than to use teensy transfer to copy stuff to/from the flash. Of course, a lot of times this is to be able to run CircuitPython, which I have very little interest in.

    In terms of the existing prop shield, if you are going to make a prop shield II for the Teensy 4.0, I would suggest bringing out the pins for the WS2812B's and speakers in a continuation of the existing 14 pins (with the speaker pins on one side, and the WS2812B pins on the other), so that it more easily fits into a standard breadboard or prototype board.

    Given the T4 doesn't have touch sensors, another thing to think about is maybe bringing out some touch pads that would work via I2C. I must admit I've been fascinated by touch panels, but I've never done anything with them except a few tests.

  11. #11
    I'm going to shamelessly plug something I'm selling on Tindie right now. Its more of a Dev board than a shield, but it has a battery charger and a 5V boost for USB host capability on battery power, along with a few more peripherals. It's pretty large at 100mm square, but it's great for projects where space isn't an issue.

    https://www.tindie.com/products/Hype...reakout-board/

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    Quote Originally Posted by CWashburn View Post
    I'm going to shamelessly plug something I'm selling on Tindie right now. Its more of a Dev board than a shield, but it has a battery charger and a 5V boost for USB host capability on battery power, along with a few more peripherals. It's pretty large at 100mm square, but it's great for projects where space isn't an issue.

    https://www.tindie.com/products/Hype...reakout-board/
    Good job !

    liking what you have done

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    Senior Member+ mjs513's Avatar
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    Quote Originally Posted by CWashburn View Post
    I'm going to shamelessly plug something I'm selling on Tindie right now. Its more of a Dev board than a shield, but it has a battery charger and a 5V boost for USB host capability on battery power, along with a few more peripherals. It's pretty large at 100mm square, but it's great for projects where space isn't an issue.

    https://www.tindie.com/products/Hype...reakout-board/
    Nice Board - but you are out of stock on the battery charger and coin cell?

  14. #14
    I'm still doing some extended testing with the battery charger module, but it will be available soon. I'm also working on providing a non-switching battery charger board that will be cheaper.

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    Senior Member+ KurtE's Avatar
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    @CWashburn - Looks interesting, so ordered one... I did not get the battery charger or Boost circuit as I am not likely to start off trying this using a battery that I would want this one to charge... But who knows. It would be nice to try out boards without having to do all of that soldering!

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    Senior Member+ defragster's Avatar
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    Quote Originally Posted by CWashburn View Post
    I'm still doing some extended testing with the battery charger module, but it will be available soon. I'm also working on providing a non-switching battery charger board that will be cheaper.
    That looks like a good setup. With updated battery support would be interested.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by CWashburn View Post
    I'm going to shamelessly plug something I'm selling on Tindie right now. Its more of a Dev board than a shield, but it has a battery charger and a 5V boost for USB host capability on battery power, along with a few more peripherals. It's pretty large at 100mm square, but it's great for projects where space isn't an issue.

    https://www.tindie.com/products/Hype...reakout-board/
    Nice looking board. Hopefully rev C will be out shortly, as having pin #23 (LRCLK1) would be nice to have.

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    Senior Member+ defragster's Avatar
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    Quote Originally Posted by MichaelMeissner View Post
    Nice looking board. Hopefully rev C will be out shortly, as having pin #23 (LRCLK1) would be nice to have.
    I ordered one - what is under the Teensy for connectivity? Surface mount contacts? I see the bottom bolts with no through holes for POGO's? And tindie pics don't show.

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    Quote Originally Posted by defragster View Post
    I ordered one - what is under the Teensy for connectivity? Surface mount contacts? I see the bottom bolts with no through holes for POGO's? And tindie pics don't show.
    Yes, I was wondering the same thing of how you connect the Teensy w/o soldering. I could understand different sized pogo pins for the outside pins compared to pins 24-33, but the pins for the SD card slot are somewhat smaller.

  20. #20
    Originally I was going to use Pogo pins, but all the ones I could find we're too small to rest on underside of the teensy pads without going all the way through. I eventually decided to go with some thing spring contacts made for RF shields. They are the same profile as the SD contact connector which is perfect.

    The only downside is that the nuts that hold the whole thing together stick out 2-3mm from the bottom, so I may consider designing a 3D printed bracket that snaps in place.

  21. #21
    I just uploaded a picture of the spring contacts on the Tindie page. Sorry for the terrible picture quality, I didn't feel like setting up my photo booth.

  22. #22
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by CWashburn View Post
    I just uploaded a picture of the spring contacts on the Tindie page. Sorry for the terrible picture quality, I didn't feel like setting up my photo booth.
    Good enough to give a much better idea, looks very neat versus a pile of POGO's. I was wondering if a wire could snake through to feed pin #23 from one of the other pin #23 points?

  23. #23
    Quote Originally Posted by defragster View Post
    Good enough to give a much better idea, looks very neat versus a pile of POGO's. I was wondering if a wire could snake through to feed pin #23 from one of the other pin #23 points?

    I'm sure it's possible, though I haven't tried. The 1mm spacer PCB blocks access on three sides, so it would have to come out from the front side of the teensy.

    Just finished shipping all the orders... it really surprised me how many orders I got in such a short time span! Kept me busy for several nights...

    I'm in the process of fixing the hardware bugs with the current Rev. B. Do any of you have any suggestions/comments of what you would like or don't like? As long as they aren't too drastic, I may be able to work them into Rev C.

  24. #24
    Senior Member+ MichaelMeissner's Avatar
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    As I said earlier, I tend to like what I called a hacker's shield that has islands with pins needed for a particular purpose (I2S1, I2S2, Serial1, Serial2, i2C0, i2C1, SPI0, SPI1, etc.). And it would be nice if there was an option for using standard cables (such as the 5x2 IDC cable, or the RJ45 cable with 8 wires).

    Now in your shield there isn't necessarily room for these island, but it would be useful to avoid the usual cross wiring that you see with breadboards. Obviously there are some issues, such as you can't use SPI1 and Serial1 at the same time, since they use the same pins. And with SPI pins, you often want to chose other pins for the CS, D/C, and reset pins, particularly if you have multiple SPI devices on the bus (such as flash memory, a SD card reader, and a display).

    Speaking of the CS pins, you may want to have pull-up resistors for the common pins, just like you have for the i2c pins.

    And a lot of times now, I find myself wishing I had a separate 5v power bus.

    But again that likely won't fit this into your current setup.

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    Senior Member+ defragster's Avatar
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    Quote Originally Posted by CWashburn View Post
    I'm sure it's possible, though I haven't tried. The 1mm spacer PCB blocks access on three sides, so it would have to come out from the front side of the teensy.

    Just finished shipping all the orders... it really surprised me how many orders I got in such a short time span! Kept me busy for several nights...

    I'm in the process of fixing the hardware bugs with the current Rev. B. Do any of you have any suggestions/comments of what you would like or don't like? As long as they aren't too drastic, I may be able to work them into Rev C.
    I was wondering about carving a through path for a wire under the spacer PCB to get that missing pin connected as long as the trace connects all the other pads?

    When those orders arrive Rev C feedback will no doubt show up

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