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Thread: Soldering custom PCBs with 4.0

  1. #1

    Soldering custom PCBs with 4.0

    I was looking to start designing my own 4.0 PCB design but wondering if the iMXRT1062 chip is something that can successfully be soldered on with a hot air rework station only to do a prototype?

    I see the chip is available in a slightly bigger 12x12mm package, and I was planning on that to try and make it a little easier. I am pretty good at hot air rework but never tried anything like this.

    Otherwise, what are the options? Solder paste, stencil, and reflow oven? Thanks for any help!

  2. #2
    Senior Member+ KurtE's Avatar
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    With my boards, I simply solder a whole T4 to the board (usually socketed)... But I am assuming you are not wanting to do that.

    Note: I don't believe that there is currently a bootloader chip by PJRC for the T4 that you can install on a board with a virgin processor chip. I know he has/is working on one, but as he mentioned yesterday many things are currently on hold while it is only him and Robin doing everything.

    Note: the first T4 beta (1052) was with one of the larger versions of the chip, so my guess is that is doable.

    As for hot air... Good question, you might try looking at the datasheet for the processor board and see if they have suggestions.

  3. #3
    Quote Originally Posted by KurtE View Post
    With my boards, I simply solder a whole T4 to the board (usually socketed)... But I am assuming you are not wanting to do that.

    Note: I don't believe that there is currently a bootloader chip by PJRC for the T4 that you can install on a board with a virgin processor chip. I know he has/is working on one, but as he mentioned yesterday many things are currently on hold while it is only him and Robin doing everything.

    Note: the first T4 beta (1052) was with one of the larger versions of the chip, so my guess is that is doable.

    As for hot air... Good question, you might try looking at the datasheet for the processor board and see if they have suggestions.
    I understand about the bootloader chip. I still want to start designing while I wait. Possibly destroy a 4.0 trying to move the boot chip and 1062 to the prototype PCB.
    I guess ill have to do the 10x10 1062 if I do that before the bootloader chip is ready.

  4. #4
    The 1062 is a BGA (ball grid array) chip. Some hobbyists have done them but it's very unlikely with a hot air station. Maybe with toaster oven reflow... If you've never done reflow, a BGA is probably about the most challenging chip. I'd start with something a little easier like discrete Rs and Cs and maybe SOICs.

    There is some info here - https://www.nxp.com/docs/en/application-note/AN3300.pdf and here https://www.nxp.com/docs/en/engineer...etin/EB635.pdf
    Try googling BGA reflow

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by KurtE View Post
    Note: the first T4 beta (1052) was with one of the larger versions of the chip, so my guess is that is doable.
    The early 1052 betas used the small 10mm size chip. The PCB was bigger only because I had not yet found a way to route so many wires in the normal Teensy form factor. All that extra PCB real estate was "empty" space with only lots of traces.

    Those BGA chips, and the 2 dual diodes and voltage regulator were soldered by a contract manufacturer, using standard equipment like a professional reflow oven. Erin & I hand soldered all the other parts (Erin did most).

    I'm not saying it's impossible to solder the BGA with a heat gun or other very low cost gear. I'm just saying those beta boards from last year aren't an example of anything like that. The BGA and other special parts were soldered by a CM with high-end equipment.

  6. #6
    I would still like to try doing it myself. Even if it means getting a reflow oven.



    In designing the PCB does anyone know the specs on the crystal oscillators?

    Is the 32.768 Khz oscillator just for the RTC? Can it be left off a design if not using RTC? No connections to P9 and N9 ?
    Or connect the 2 pins with listed capacitors?

    What is the 24MHz used for? Clock speed? Is it needed if running only at default 396 MHz or only if changing the clock speed?


    I also have no need for Battery/VBAT So should pin M9 VDD_SNVS_IN just be connected to 3.3v , and do I just leave Pin K8 VDD_USB_CAP unrouted?


    Thanks for the help.

  7. #7
    I had a spare 3.6 here so I decided to see how hard it was to rework. I used my hot air rework station and took off the chip. Then some flux and cleaned up the pins. Reworked it back on, it works!

    While the life of the chip was probably shortened by doing this, I think it shows it could be done for prototyping with hot air!

  8. #8
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    Quote Originally Posted by bigboosted View Post

    In designing the PCB does anyone know the specs on the crystal oscillators?

    Is the 32.768 Khz oscillator just for the RTC? Can it be left off a design if not using RTC? No connections to P9 and N9 ?
    Or connect the 2 pins with listed capacitors?

    What is the 24MHz used for? Clock speed? Is it needed if running only at default 396 MHz or only if changing the clock speed?


    I also have no need for Battery/VBAT So should pin M9 VDD_SNVS_IN just be connected to 3.3v , and do I just leave Pin K8 VDD_USB_CAP unrouted?
    Hi. All of your questions can be answered through browsing the datasheet: https://www.nxp.com/docs/en/nxp/data...XRT1060CEC.pdf

    For clocking, see Table 3, page 17. It has most of the parameters you need to create the clock circuitry. TLDR, leave RTX_XTAL pins floating if not using RTC. No capacitance or crystal is needed in that case. 24MHz crystal is necessary and is used by the internal PLL to generate the higher speed clocks. You need it regardless of the speed you are running at.

    For VBAT, I'd say connect VDD_SNVS_IN to 3V3, and do not connect VDD_USB_CAP to VDD_SNVS_IN. I assume you need that cap on there for LDO stability for the internal PMU, so definitely do not leave that pin floating.

    The above conclusions are just my deductions from the datasheet - they could be incorrect. Read it yourself to be more confident.


    I have some followup questions also regarding putting the 4.0 on a custom PCBA. KurtE mentioned that a bootloader chip for 4.0 does not exist as a standalone item that can be bought from PJRC. Does this suggest that the bootloader chip cannot be removed from an existing 4.0 and moved onto a custom PCBA with a fresh M7 to get the same functionality? Do both the bootloader and the M7 need to be moved from an existing 4.0 together as a pair? Does the SPI flash play any role in this? Or do we have to wait for the standalone bootloader from PJRC to do custom 4.0s? It was my assumption that a 4.0 can be purchased, and then the M0 (bootloader) alone can be used to turn an M7 into a Teensy, but KurtE's comment seems to go against that.

    Thanks.

  9. #9
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by cknight10010 View Post
    ...I have some followup questions also regarding putting the 4.0 on a custom PCBA. KurtE mentioned that a bootloader chip for 4.0 does not exist as a standalone item that can be bought from PJRC. Does this suggest that the bootloader chip cannot be removed from an existing 4.0 and moved onto a custom PCBA with a fresh M7 to get the same functionality? Do both the bootloader and the M7 need to be moved from an existing 4.0 together as a pair? Does the SPI flash play any role in this? Or do we have to wait for the standalone bootloader from PJRC to do custom 4.0s? It was my assumption that a 4.0 can be purchased, and then the M0 (bootloader) alone can be used to turn an M7 into a Teensy, but KurtE's comment seems to go against that.

    Thanks.
    PJRC has yet to release a T_4.0 capable bootloader chip for a New/RAW 1062, including the ones sourced on the production boards. It is pending and may not be too long in coming - depending on work interruptions - Paul noted not too long ago.

    Paul Noted:: The production T_4's get a RAW 1062 installed and his test fixture during hardware test 'formats' the raw 1062 for Teensy use using the current bootloader chip.
    It is a WIP is moving the RAW 1062 format into a saleable bootloader chip - but that is not a trivial task to avoid bricking anything during the fuse burning setup 'formatting' process - or after if it is not done properly as done with the Test Jig used on every new Teensy.

  10. #10
    More info from Paul in this thread about the bootloader.
    https://forum.pjrc.com/threads/57132...4.0+bootloader

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