Questions on Teensy4.1 schematic

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Hi Paul,

I'm adding the Teensy4.1 schematic to use IMX1062 chip on my custom board. I'm having a hard time to understand how to burn the bootloader and firmware on IMX.
There are many explanation for boot configuration, but I want to do everything only via usb otg1 port like in the Teensy4.1 board. Is it possible? I duplicated the teensy circuit to the custom board as it is. I added a MKL02Z32VFG4 to the board like in the Teensy board.
Or should I add JTAG header to the board for flashing the firmware and bootloader?
Would you like to let me know the best solution for programming the firmware and burning the bootloader on my custom board? Where can I find the reference design for it?

Thanks in advance
Milovan.
 
Until Paul may comment or correct ...

To design using Teensy parameters and schematic it must include the external custom bootloader MCU programmed and sold by PJRC. Note however at this time that external bootloader MCU to power up with a virgin 1062 MCU to be programmed is not yet available and while an important work in progress - current events with limited staffing and the complexity of doing it with secure boot functionality to allow off chip program security - is taking much longer to get the needed cycles.

That external MCU holds the Teensy bootloader programming code and only supports programming through the primary Device USB port as designed into the schematic and creating typical Teensy usage when running the 1062 MCU.

Other setups or methods of programming are certainly possible - but not in the scope of Teensy and PJRC.
 
Hi Defragster,

Thanks for your reply.
So you mean it's not possible now to use the Teensy 4.1 schematic on my board to program the 1062 MCU? Or can you provide the pre-baked external bootloader MCU with the bootloader?
Otherwise, for now, should I use only the Teensy board as it is?

Milovan
 
At this time the only option is to include a Teensy boards as is.

The bootloader is only maintained on the external MCU chip - not yet in production for sale.

The 1062 MCU is fully controlled and programmed by that external MCU on both the T_4.0 and T_4.1. Currently a factory 1062 is prepped during production to allow the bootloader MCU find it in a usable state from NEW, so even pulling the current bootloader MCU would not be able to function with a NEW production 1062.
 
At this time the only option is to include a Teensy boards as is.

The bootloader is only maintained on the external MCU chip - not yet in production for sale.

The 1062 MCU is fully controlled and programmed by that external MCU on both the T_4.0 and T_4.1. Currently a factory 1062 is prepped during production to allow the bootloader MCU find it in a usable state from NEW, so even pulling the current bootloader MCU would not be able to function with a NEW production 1062.

I suspect if you pulled the MCU and bootloader chip from a teensy 4.x, you could install it on a custom board and it would likely work, though.
 
I suspect if you pulled the MCU and bootloader chip from a teensy 4.x, you could install it on a custom board and it would likely work, though.

Nope, not as last noted by Paul. Only factory test jig currently preps the NEW MCU for use by the existing/shipping bootloader MCU.

That is part of the need and wait for those bootloader MCU's.

so AFAIK this has not been updated since 11/16/20:
Or as an alternative, are the bootloader chips on shipped T41s capable of setting up virgin IMXRT chips?

No, they are not. If you desolder the MKL02 chip from a Teensy 4.1 and try to use it with a virgin IMXRT, it definitely will not work.

* thx @KurtE for the link
 
I have another question for Teensy4.1 schematic.
Is the internal DC-DC regulator of the 1062MCU in the circuit? Regarding the 1062 MCU hardware development guide, a 1ms delay circuit should be connected the DCDC_PSWITCH pin when the internal DCDC regulator is used.
However, I can't see any RC delay circuit connected to the PSWITCH. That means the internal DCDC circuit is not used on the Teensy4.1 board?

Milovan
 
However, I can't see any RC delay circuit connected to the PSWITCH. That means the internal DCDC circuit is not used on the Teensy4.1 board?

No, would be a very wrong assumption. The absence of the RC delay circuit does not mean that at all. The DCDC buck converter is indeed used, as you could infer from the 4.7uH inductor connected to DCDC_LP, the many capacitors at DCDC_IN & VDD_SOC_IN, and the lack of any other way for to be create the ~1.2V needed to run the CPU. Startup sequencing is simply done another way.
 
Regarding the hardware reference design, it's connected to DCDC_IN through a 1ms delay circuit. However, as you can see, PSWITCH was not connected to any power source on the Teensy4.1 board. Is it right?
Currently, the DCDC_PSWITCH is connected to the ground via a 100k ohm resistor. I know the DCDC_PSWITCH needs to connect to the ground for bypassing the DCDC.
Or what is DCDC_PSWITCH used for?
 

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Thanks for your detailed explanation.
I'm not going to use MKL02Z in my custom circuit because this chip is not available to users as a chip pre-baked by the bootloader. Instead, I'll add JTAG to the board. In that case, how should I design the circuit for DCDC_PSWITCH pin? Should I add a 1ms delay circuit like in the reference design guide? Otherwise, it still needs to be connected 100kohm pull down resistor like in the teensy board?
Also, in this case, what's the circuit for VDD_HIGH_CAP, NVCC_PLL and VDD_SNVS_CAP pin? Can I keep the circuits for those pins as they are?

Milovan
 
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