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Gemma won't enter bootloader mode
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Gemma won't enter bootloader mode

by absurdstarfish on Sat Aug 01, 2015 11:43 am

I have 3 gemma's (two adafruit and one arduino) that I can't seem to get into bootloader mode. I have tried 3 usb micro cables and both ports on my MacBook Pro (all of which function normally with other hardware) but still when I press the reset button the red light illuminates solid for ~3 seconds and then turns off without strobing. Attempting to load any code through IDE returns the "Could not find USBtiny device (0x1781/0xc9f)" error.

I couldn't find any previous threads relating to this, but if you know of one please link me :)

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Re: Gemma won't enter bootloader mode

by adafruit_support_mike on Sun Aug 02, 2015 1:21 am

Try re-flashing the bootloader: https://learn.adafruit.com/introducing- ... bootloader

The tutorial is for the Trinket, but the Gemma uses the same microcontroller and firmware.

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Re: Gemma won't enter bootloader mode

by absurdstarfish on Mon Aug 03, 2015 11:56 pm

Decided to try one more cable before I went through the trouble of flashing the bootloader, turns out that was the problem.

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Re: Gemma won't enter bootloader mode

by adamjdanger on Thu Jul 28, 2016 4:22 pm

I had a similar problem on a macbook pro and solved it but plugging the gemma into a usb hub rather than straight into the mac's usb port.

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Re: Gemma won't enter bootloader mode

by socrates6 on Sat Feb 03, 2018 8:58 pm

I have the same problem. When I push reset on the gemma the LED goes through a rainbow of colors. Im assuming that isnt bootloader mode.

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Re: Gemma won't enter bootloader mode

by adafruit_support_mike on Sun Feb 04, 2018 12:59 am

Verify your USB cable by using it to connect some other, known-working device to the computer.

There's a plague of charge-only cables out there with USB connectors at both ends but no wires for the data signals. We see people get caught by them every day.

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Re: Gemma won't enter bootloader mode

by socrates6 on Sun Feb 04, 2018 6:05 pm

Yeah, the cable works for the trinket.

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Re: Gemma won't enter bootloader mode

by adafruit_support_mike on Mon Feb 05, 2018 3:02 am

What do you see in the Device Manager or System Information USB pane when the Gemma is connected to the computer?

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Re: Gemma won't enter bootloader mode

by tkwanjp on Thu Dec 13, 2018 11:48 am

I'm in the same situation.

I just got a new Gemma v2, have 4 cables.

Tried
cable 1, failed. Green LED lit but not for red LED.
cable 2, succeeded! Red LED also blinked fast.
So I uploaded a sketch. Then tried uploading another sketch, failed back to the same situation.

Tried
cable 3, failed.
cable 4, succeeded! Red LED also blinked fast.
So I uploaded a sketch. Then tried uploading another sketch, failed back to the same situation.
(tried all combination of cables 1-4.)

What can I do?

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Re: Gemma won't enter bootloader mode

by adafruit_support_mike on Fri Dec 14, 2018 1:02 am

@tkwanjp: Please start a new thread for your issue.

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Re: Gemma won't enter bootloader mode

by tkwanjp on Sun Dec 23, 2018 5:33 am

@adafruit_support_mike essentially my problem is just as same as here; won't enter boot loader mode.

I've replaced the previous Gemma to a new one, but it still don't enter boot loader mode.

connect Gemma to the computer, green LED lit. Push the button on the Gemma, red LED lit for a couple of second then turns down.
Upload sketch, get an error:
"avrdude: Error: Could not find USBtiny device (0x1781/0xc9f)".

Using Adafruit Gemma (with a black PCB board). Got through the instruction of [Setting up with Arduino IDE https://learn.adafruit.com/introducing- ... rduino-ide].

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Please be positive and constructive with your questions and comments.