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Thread: Future Teensy features & pinout

  1. #476
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    @kdharbert, what voltage range, speed, and resolution do you need?

  2. #477
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    voltage range: 0-3.3v
    Speed\res: Low end: 16bit 44.1khz high end: 16bit 500khz

  3. #478
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    Quote Originally Posted by kdharbert View Post
    voltage range: 0-3.3v
    Speed\res: Low end: 16bit 44.1khz high end: 16bit 500khz
    Analog Devices, TI, Maxim, Microchip and others make multi-channel ADCs that can be easily managed over SPI or I2S. These are available in 2-8 channel versions at 1+ msps per converter. A search on Mouser, Digikey, or LCSC will show options.

    Design & layout of a 3.3V 16 bit converter is not trivial. At 50uV/bit it requires knowledge of analog PCB design practices for good noise performance. If you can reduce the bit depth or increase the voltage range it will make the design process much easier.

  4. #479
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    One question:
    It would be interesting make possible to solder as SMD?. The problem with trough hole is the it drills not only te top side but also internal ones so is more difficult to design PCBs. Also more difficult for production. The solution is easy: to expand a little to make SMD pads at the border close to pins so it would be possible solder as SMD and also pins using the same PCB

  5. #480
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    Quote Originally Posted by jlopez2022 View Post
    It would be interesting make possible to solder as SMD?.
    Only if there are no bottom mounted components, or you must use cut-outs and then it does not matter much if there are through holes.

  6. #481
    Senior Member Blackaddr's Avatar
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    Quote Originally Posted by jlopez2022 View Post
    One question:
    It would be interesting make possible to solder as SMD?. The problem with trough hole is the it drills not only te top side but also internal ones so is more difficult to design PCBs. Also more difficult for production. The solution is easy: to expand a little to make SMD pads at the border close to pins so it would be possible solder as SMD and also pins using the same PCB
    Normally castellated holes are used for SMD soldering a PCB down to another one, but that only works when there are no components on the bottom side, so that unfortunately isn't an option for Teensy.

    If your concern is having to put through-holes through your carrier PCB, and you can afford the height of the female headers, you can also just use 0.1" SMD female headers rather than PTH.

    Otherwise, I think the upcoming MicroMod version will solve some of these issues as the M.2 connector is SMD (presuming the M.2 breaks out all the pins you need).

  7. #482
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    Quote Originally Posted by jlopez2022 View Post
    One question:
    It would be interesting make possible to solder as SMD?
    This topic was discussed in some depth earlier in this thread. The only practical ways do this is for the board to have no components on the bottom, or require a cutout on the baseboard. Single side components has been done by at least one manufacturer. Among other things there is an impact on noise performance due to the increased distance between the decoupling caps and the BGA pins. My opinion is that I would rather have a more robust board, as opposed to a single-sided (components) board.

  8. #483
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    Quote Originally Posted by mlewus View Post
    This topic was discussed in some depth earlier in this thread. The only practical ways do this is for the board to have no components on the bottom, or require a cutout on the baseboard. Single side components has been done by at least one manufacturer. Among other things there is an impact on noise performance due to the increased distance between the decoupling caps and the BGA pins. My opinion is that I would rather have a more robust board, as opposed to a single-sided (components) board.
    Agreed about the stability.
    The greater distance between capacitors and pins would not likely affect performance at stock (or lower) clock speeds. However, for those of us (and I'm sure there are a large number of us) that overclock the CPU core to accelerate processing of certain time sensitive tasks this would introduce a VERY undesirable instability during these brief over-clocks. Another feature that would be harmed would be the ADC performance since the decoupling on the ADC power inputs is critical to clean conversions.

  9. #484
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    Quote Originally Posted by Blackaddr View Post
    Otherwise, I think the upcoming MicroMod version will solve some of these issues as the M.2 connector is SMD (presuming the M.2 breaks out all the pins you need).
    I got a couple of the M.2 connectors and they look to be pretty tricky to hand solder. Lots of solder wick, for sure. I'd go for reflow. Definitely not for your average hobbyist. Costs a lot more than 2 rows of 2.54mm pitch headers, too. Micromod doesn't give me more GPIOs than a T4.1 and no Ethernet so I probably won't be using it. Seems like a step back from the T4.1.

  10. #485
    Senior Member manicksan's Avatar
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    Also the m2 connector is double sided,
    which means it's very hard to solder the top side smd pins.

  11. #486
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    Quote Originally Posted by DavidWH1968 View Post
    Agreed about the stability.
    Another feature that would be harmed would be the ADC performance since the decoupling on the ADC power inputs is critical to clean conversions.
    Which is why I have been using I2C ADCs - you can get a lot cleaner signal into (and out of) one of those. An ADC in a microcontroller is subject to a lot of compromises. I like it when the conversions happens far from the EMI factory. Makes my paltry analog skills look positively brilliant.

  12. #487
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    You are right. ADC's in MCU's are in VERY close proximity to many other peripherals which can introduce their own noise and compromise the integrity of an analog signal. Discrete ADC's are still made for that very reason.

  13. #488
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    Also not that the silicon process for low-power high speed CMOS is not necessarily ideal for a high performance
    sigma-delta modulator which is essentially a precision analog piece of circuitry. Laser trimming is sometimes used
    for the highest-performing analog chips, which requires feature sizes far larger than modern high-speed CMOS, often
    taking up significant die area.

    If you do have an ADC on an MCU, it will perform best if you halt the processor during acquisitions.

  14. #489
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    Sorry, the M2 connector will allow inserting teensy as a DDR memory in a PCB?

    About using 0.1' SMD connectors, it is a good idea, but I should use male ones, so I will not have troubles with heigh, also some components could be inserted under the teensy

  15. #490
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    Quote Originally Posted by manicksan View Post
    Also the m2 connector is double sided,
    which means it's very hard to solder the top side smd pins.
    Just last weekend I hand soldered a few M.2 connectors on those MicroMod breakout boards. The rows of pins on each side were about the same.

  16. #491
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    i.MX RT1170 - Arrow Hands-On Training
    https://register.gotowebinar.com/reg...87000132060173

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