Roomba 980 not booting

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Roomba 980 not booting

Postby StefanKrupop » Yesterday, 9:13 pm

Hi all,

I bought a defective Roomba 980 off eBay and am now trying to fix it. From the outside, there is no sign of live in the unit, so no beeps or LEDs or anything, even if I directly provide power from a lab supply to the battery contacts.
However, the bootloader in the STM32 (U6) seems to be at least partially working, as I get the following UART output on J25:

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Normal reset

iRobot Roomba Bootloader svn version: 4042
option bytes read protect:  1
option bytes write protect: 0xfffffc00
option bytes user:          0xff
usb_activity_timeout_ms: 30000
No connection in 30 seconds, booting the app

External flash manufacturer ID is 0x9d6017
External flash unique ID is 0x5031473635370009

This repeats over and over again, it never actually "boots the app" but rather restarts. I desoldered both flash chips (U11 for the STM32 and U12 for the Wifi module) and dumped them externally. Content seems to be relatively ok (some interesting strings).

I then attached a logic analyzer to U11 and recorded what the bootloader actually does with the flash. It reads the JEDEC ID (shown as the "manufacturer ID" in the bootloader output), the unique ID and then the first 511 bytes of the flash. After that it seems to reset.

So I conclude that something might be wrong with my first bytes. One thing I already see is that my external programmer and the SPI log disagree on the 3rd byte: The programmer reads it as 0x00 (verified multiple times), while the trace shows 0xff is returned.

I'll try to fix that, but I was wondering whether somebody could help me out with a dump of their first 512 bytes of U11? For me it's all 0xff except the first 8 bytes. There I have
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0x01 0xff 0x00 0xff 0x00 0x00 0x01 0x00

. Bytes 5-8 could be the start address of the firmware image in the flash. But I do not know what the bootloader expects to be in Bytes 1 to 4...

Thank you very much!

Kind regards,
Stefan Krupop
Posts: 1
Joined: Yesterday, 8:58 pm

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