Teensy 4.1 custom board, bootloader 2 blinks

M

Maaz

Member
We have a custom board with MIMXRT1062DVJ6B and used bootloader chip from a teensy 4.1 dev board. The bootloader is now blinking twice. We have double checked the MKL02 and IMXRT1062 connection, and pretty confident that solder is good. When its is connected to the PC it make peripheral connect sound.
I have checked the powerup sequence and its same as mentioned on the website.

Here is the schematic of the custom board.
1713956665324.png
 
Thanks for the quick response. But we are not getting 10 blink, we are getting two blinks. Can you take a look at the design, maybe MCU is not running correctly to establish JTAG comm.?
 
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Does "bootloader chip from a teensy 4.1 dev board" mean you desoldered and reused the chip from an actual Teensy 4.1 circuit board, or you purchased this T4 bootloader chip?

Either way, 2 blinks means the JTAG connection is not working at all. It could mean the RT1062 powered up incorrectly. Or it could mean your wiring or soldering is bad. Impossible to tell which from only this info. Your schematic seems to match the Teensy 4.1 schematic, except we can't see your voltage regulator and you have several 3v3 power symbols that don't seem to connect to anything that provides 3.3V (but you must have 3.3V because the bootloader chip is able to blink)... so maybe this isn't the full schematic?
 
Thanks Paul, we resolder the MKL02 chip (not from here T4 bootloader chip) which was removed from teensy 4.1 dev board and it works! Code is flashing and test led is blinking. My question is why is this working? as it was paired for the MCU on dev board?
 
Maaz said:
My question is why is this working?
Click to expand...

Basically, luck.

As I tried to explain on that other thread, the U2 chip is never meant to be desoldered and used this way. The behavior is undefined. It might work, might fail, might partially work, might be unreliable.
 
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