Epson Moverio BT-200 (epson-embt2ws)

Features
Flashing
USB Networking	Works
Internal storage	Works
SD card
Battery	Broken
Screen
Keyboard
Touchpad
Multimedia
3D Acceleration
Audio	Works
Camera	Broken
Camera Flash
Connectivity
WiFi	Works
Bluetooth	Partial
GPS	Partial
Miscellaneous
FDE
USB OTG
Sensors
Accelerometer	Works
Magnetometer	Works
Ambient Light
Proximity
Hall Effect
Haptics
Power Sensor

Epson Moverio BT-200
	; CHANGE_ME
Manufacturer	Epson
Name	Moverio BT-200
Codename	epson-embt2ws
Released	2014
Type	glasses
Hardware
Chipset	TI OMAP 4460
CPU	2x1.2 GHz Cortex A9
GPU	PowerVR SGX540
Display	960x540 see through glasses
Storage	8GB eMMC + uSD slot
Memory	1024 MB
Architecture	armv7
Software
Original software	Android
Original version	4.04 (Kernel 3.0.21, U-Boot 1.1.4)
postmarketOS
Category	testing
Pre-built images	no
Mainline	yes

Contributors

Andi

Users owning this device

How to influence/change boot order

Boot order is eMMC, USB, UART, uSD. That can be overwritten by software until the next cold boot: Commands in U-Boot, similar could be done via /dev/mem

mw.l 0x4A326A0C 0xCF00AA01
mw.l 0x4A326A10 0xC
mw.w 0x4A326A14 0x0
mw.w 0x4A326A16 0x43
mw.w 0x4A326A18 0x45
mw.w 0x4A326A1A 0x05
mw.w 0x4A326A1C 0x0
mw.w 0x4A326A1E 0x0
mw.l 0x4A326A00 0x4A326A0C

and then warm-reboot (e.g. reset button or reset command in newer u-boots).

If you want to reorder the boot order temporarily, you can do that from the original system if it is rooted, use setup-bootchoice from https://github.com/akemnade/bt200tools.

eMMC boot can be skipped using a 470 Ohm resistor from eMMC DAT 0 to GND on powerup. So that would be a recovery if loader on eMMC is broken.

Accessing serial console in original system

JP1 (soldering jumper on the back side = gpio-138) needs to be shorted to enable serial console on factory kernel/u-boot. (4 2.54mm pitched holes). Voltage level is 1.8V

Boot process of the original system

Xloader is located at sector 256 and loads U-Boot from sector 512 as a raw headerless binary on the same device as Xloader also was loaded from. CONFIG_SYS_TEXT_BASE of such a u-boot has te be set to 0x80e80000. Size limit is 0x60000 bytes.

Factory U-Boot tries to load a sdboot.scr from the first partition (which must bet FAT) of the uSD card which is executed if the md5sum of the first line is 92b12a37d1913ac41d2956120a475aca, if not, normal boot from eMMC is done. Fastboot can be activated via commandline.

How to enter flash mode

Installation

System can be installed on uSD card. To be able to boot that you need to either:

zero the xloader and u-boot area of the eMMC (after doing a backup)
hack the integrated u-boot bootcmd to ignore check_code test results to boot the sdboot.scr (e.g. via usb mass storage mode via ums command): there is some
```
 checkcode; if test $? -eq 1
```
in the builtin u-boot env, replace that by e.g.
```
 checkcode; if test 33 -eq 1
```
use one of the methods to temporarily change boot order
use u-boot commandline to manually load stuff (which can also be a modern u-boot, see u-boot wiki)