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[PX3 & 5] [OTG] - No Headunit Mod, recover or flash a SOM with a simple USB cable

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Thanks Meter: 338
 
By marchnz, Senior Member on 22nd March 2018, 05:19 AM
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"Factory" Recovery for MTCx PX3 and PX5 SOM.

Finally - OTG for all without modifying your headunit. With only basic electronic/soldering skills, get OTG and fearlessly flash or recover a 'bricked' Rockchip PX3 or PX5 SOM.

See attached pics for making an OTG cable from a USB cable and two resistors.
Resistors are 12K and 15k (22k is probably better) or anyone of the following. combinations. These resistors are necessary as 'voltage dividers', with a value between 1.8v and 3.3 OK. These simply place a logic '1' on recovery and USB-OTG to 'tell' the SOM to go into OTG recovery mode.
R1 | R2
-------------------
1K | 1.8K
2.2K | 3.3K
10K | 18K
12K | 22K

Get Windows Driver [Driver assistant v4.5] and [Android tool 2.39] for direct/OTG SOM flashing here.. Be sure to edit [android tool] .ini file to set English, otherwise tool will be rendered in Chinese.

This tool for dumping / getting full backup of SOM
Excellent tool, thanks @RedScorpioXDA

Note - all tools and driver have equivalent Linux versions.

Further Details to follow.

Credit (thanks!) to @scorillo_ro for the detailed image/connections diagram.

Worst case - SOM doesn't respond - force 'maskrom' detailed here explaining what MaskRom is and here on how to for your PX5 (px3 is similar.) Steps are: Power Off SOM and disconnect USB to PC. Use Tweezers, apply power/connect USB. Hold until Windows Device chime is heard (within about 2 seconds of power on.) See attached pic.

Warning : Use thin pins for OTG cable in order to avoid the damage of the SOM connectors, although along the thread it has been noted many times that damage to the SOM socket is very likely to happen if thick pins are used...OR buy SOM header from Aliexpress, digikey etc.[/COLOR]
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22nd March 2018, 06:14 AM |#2  
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Nice work @marchnz !
A full step by step and pictures howto should be made now and all those PX5 users without sdcard slots will be able to use this method to get Android8!

LE. I drew a schema
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23rd March 2018, 09:57 AM |#3  
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Quote:
Originally Posted by scorillo_ro

Nice work @marchnz !
A full step by step and pictures howto should be made now and all those PX5 users without sdcard slots will be able to use this method to get Android8!

LE. I drew a schema

So with this methon, will be possible to flash on 6.0 unity, the recovery and the system of android 8.0?
23rd March 2018, 10:32 AM |#4  
Quote:
Originally Posted by lucajust

So with this methon, will be possible to flash on 6.0 unity, the recovery and the system of android 8.0?

Absolutely! I've done it a bunch of times. You can either use the sdupdate.img from the Oreo upgrade thread to load the Oreo recovery and then install the oreo .zip from recovery OR a full set of partition images.

I have a full set of partition images if needed, they're about 25gb but should compress right down (that 25gb includes [user] partition which is an empty partition.
23rd March 2018, 10:52 AM |#5  
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Good... I'll try... But the process Need a PC no? Becouse with the unit with SD card slot needs PC only to prepare the sd card for android 8 recovery

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23rd March 2018, 11:24 AM |#6  
Quote:
Originally Posted by lucajust

Good... I'll try... But the process Need a PC no? Becouse with the unit with SD card slot needs PC only to prepare the sd card for android 8 recovery

Inviato dal mio Mi A1 utilizzando Tapatalk

Yes, PC. I've updated the post to include links to tools and driver. Driver 4.5 & Android tool works on Win7 - Win 10, x86 and x64.


For those without SDCard wanting to upgrade to Oreo:
You could try OTG flashing the Oreo sdupdate.img, fit SOM back to headunit and then try loading the Full Oreo update.zip from USB. Otherwise I will need to upload the full Oreo partitons dump with instructions....over the next few days....
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23rd March 2018, 12:07 PM |#7  
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Quote:
Originally Posted by marchnz

Yes, PC. I've updated the post to include links to tools and driver. Driver 4.5 & Android tool works on Win7 - Win 10, x86 and x64.


For those without SDCard wanting to upgrade to Oreo:
You could try OTG flashing the Oreo sdupdate.img, fit SOM back to headunit and then try loading the Full Oreo update.zip from USB. Otherwise I will need to upload the full Oreo partitons dump with instructions....over the next few days....

Thanks... What are the "SOM"?

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23rd March 2018, 12:13 PM |#8  
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It is my understanding that I can flash the SOM without the rest of the board?

So just disconnect the SOM then hook up the USB as per the diagram and it will be detected by windows. Use android tool / RockChip Batch Tool with a android 6/8 recovery.

The issue I have is that the nand doesn't look like its recognised after an attempt to flash oreo. Please see attached picture.
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23rd March 2018, 12:18 PM |#9  
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Quote:
Originally Posted by Harsesis

It is my understanding that I can flash the SOM without the rest of the board?

So just disconnect the SOM then hook up the USB as per the diagram and it will be detected by windows. Use android tool / RockChip Batch Tool with a android 6/8 recovery.

The issue I have is that the nand doesn't look like its recognised after an attempt to flash oreo. Please see attached picture.

Yes, you understood correctly. This method may save you...
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23rd March 2018, 12:22 PM |#10  
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Quote:
Originally Posted by scorillo_ro

Yes, you understood correctly. This method may save you...

You mentioned a full partition dump. I'm hoping I don't need this. I remember reading that the partition structure needed to be changed for android 8. Do you have any idea how to do this via the tools? I remember reading about something called a storagemap that rockchip uses.
23rd March 2018, 12:27 PM |#11  
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Quote:
Originally Posted by Harsesis

You mentioned a full partition dump. I'm hoping I don't need this. I remember reading that the partition structure needed to be changed for android 8. Do you have any idea how to do this via the tools? I remember reading about something called a storagemap that rockchip uses.

Wait for @marchnz to put this information here. Meanwhile you can start building your USB JIG.
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