Tiny Core not booting on some pi3a+

[SteveatXitek]

We have been using pi3a+'s with Tiny core for a while now but have a collection of pi3a+ that wont boot Tiny Core (keeps rebooting before anything reaches the monitor) so presumably the copy to ram is failing. The pi3a+'s boot Raspian fine. We have tried different cards / speeds and sizes . We have use some 300 pi3a+'s and have 20 that exhibit this issue. Any idea's as to whats going on / fix?
Steve

[Paul_123]

Do you even see the rainbow screen?   But sounds like a weak power supply.

Tinycore runs the CPU in performance mode through the entire boot process(after boot, it drops back to powersave governor), which will tax a poor power supply.

[Rich]

Hi SteveatXitek
Welcome to the forum.

... We have use some 300 pi3a+'s and have 20 that exhibit this issue. ...

Just to be clear, are those 300 pi3a+'s all running the same version of Tinycore, and
20 of them are stuck in this reboot loop?

That would suggest something is different about those 20 units:
different firmware
different chip part numbers on those boards
different chip part manufacturers on those boards
boards purchased from a different vendor
power supplies for those boards are not up to snuff
etc.

[gadget42]

and to add to @Rich's list would be to acknowledge counterfeit components(yes, including the board-level stuff that takes magnification to even visually inspect)...sigh...

[SteveatXitek]

Ref PI3A+sourcing : we purchased in two batches of 150 from the same supplier (Farnell)
Ref PSU : does the same running from a 30A bench PSU
reboots without displaying anything
all using the same iso for flashing the cards and the cards are 8gb all from same batch (have tried swapping and using high speed cards also on the "failing" Pi3a+
All these "failing" boards will fully boot and run the latest full Raspian desktop with wifi enabled an internet active
and its just 20 out of the 300 Pi3a+'s
Tried everything We can think of here, any further ideas?

[gadget42]

are you able to determine if the failing 20 units all came from one "batch" from your purchases via farnell?

i wonder if we can determine a serial number range for the failing units so that it might be possible for others to determine if they have these failing units as well?

[Rich]

Hi SteveatXitek
I seem to remember reading somewhere that the boot loader
on these devices can be updated. Are those 20 boards using
the same boot loader as the other 280?

[gadget42]

according to this post:

https://forums.raspberrypi.com/viewtopic.php?t=352778#p2114933

If it DOES boot when using bootcode.bin with the timeout file, then you may be able to get it working by setting another OTP bit that increases the wait time for the USB drive to become ready from the default 2 seconds to 5 seconds (this is a permanent change). To enable the additional wait time for USB drives, add "program_usb_boot_timeout=1" to config.txt on a Raspbian SD card and boot it once in the system. After that the system will wait up to 5 seconds for USB drives to become ready.

what if the ones that don't work properly with TCL maybe have this 2 second timeout and that isn't long enough for TCL?

(please read the whole post and probably the whole thread for the entire content/context)

[Paul_123]

1) The timeout only applies to drives connected to the USB port.  It does not affect /dev/mmcblk0
2) While you can manipulate the OTP, there is no upgradeable bootloader on the pi3* boards.  It is all files on the boot partition.
3) If you connect HDMI and sdcard image on the built in SD card.  You should at a very minimum see the rainbow square screen from the firmware.   If you do not see this, then you have some other hardware problem.

all using the same iso for flashing the cards

We do not supply iso's, they are img files.   Where specifically have you downloaded from?