PS4 UART Guide

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This is a guide for diagnosing pulsing blue light of death (BLOD) on the PS4.

Tools you will need:

  • A programmer to dump the flash (I use CH341A)
  • Proper adapter for the bios chip (see below)
  • Programmer Software (I use AsProgrammer)
  • Serial monitoring software (I use Arduino IDE)
  • A USB to TTL 3.3v converter (I use CH341A)
  • Some insulated wire (needs to be thick enough)
  • Hex Editing Software (I use HxD)
  • Soldering Iron
  • Hot air station
  • Solder
  • Flux

Starting Up

BwE has provided a 'UART & Programmer Collection' pack which will aid in this project. It contains all of the following:

  • CH341A Programming Software
    • AsProgrammer 2.03a
    • SkyGz CH341A Mini Programmer Black Edition 1.18
    • NeoProgrammer 2.2.0.8
    • Modified SkyGz CH341 Programmer v1.1.1.25 by Kovzhun Mikkhail Alexandrovich (English/Russian)
  • CH341A Drivers
  • Logic Analyzer Software
    • Pulseview
    • Zadig (USB Driver)
  • PuTTY
  • USB TTL Drivers
    • FT232
    • PL2303
  • FT232RL
  • PL2303
  • CH341A Programmer (And USB TTL)
  • Depending on the USB TTL device you have you need to install the drivers for it. If you are not using the above pack, download the appropriate driver below.

    Dumping/Patching

    Desolder your NOR chip from the board, if you do not know where that is or how to do it I suggest you discontinue this adventure early.

    Next is to solder the chip to a breakout board, as seen below.

    If you have a SOIC chip (it has little legs) then soldering is quite easy, just use heat.

    If you have a WSON chip (the legs are not exposed, as pictured below) then you must mask off the ground pad with something non-conductive and heat resistant. I used kapton tape.

    Once it is on the breakout board, read the chip with whatever you have chosen to program it with. Teensy using NORWay or a CH341A for example.

  • Desoldered NOR, masked to avoid ground shorting on reader.
  • Placing NOR on breakout board
  • NOR being read on breakout board (Masked to avoid grounding)
  • Using the aforementioned software (Or nothing if using NORWay) dump the NOR at least twice and compare the MD5 of each dump, you can use HxD or some other tool to do this. Generally if you have desoldered the NOR and put it on a breakout board there is minimal chance for failure.

  • Next, using the BwE PS4 NOR Validator, validate the NOR and patch it for UART. This can be done either at the end of the validation process or the start - choose your option in the menu provided.

    Writing

    Using the same software you used to dump the NOR start by erasing it entirely and then writing your patched dump. Erasing it seems to fix a few issues that may cause the BLOD in PS4's (and even some issues in the PS5). This makes the whole process longer, but it is worth it.

    Once this is done, remove the NOR chip from the breakout board and put it back on the console the way you found it. Ensure everything is clean and well presented.

    Soldering UART Pins

    The only 2 pins you will need to solder is Ground, and TX. Before you start, ensure that the TX pin on your PS4 is indeed getting 3.3v on start up.

    If your USB TTL has jumpers, ensure that it is set to 3.3v.

    Attach or solder the ground and TX lines to the USB TTL and plug it into your computer. Do not use cable that is too thick or too thin. I generally just use jumper wires as they are easy to plug into the USB TTL device.

  • UART pins for SAC-001
  • UART pins for NVG-002
    UART pins for SAE-004
  • UART pins for SAA-001
  • Assembly

  • UART on a 72xx
  • If you want to keep this permanent, ensure that your cables are long enough and you are able to route to the USB TTL while the case is closed.

    Make sure the pins are insulated when reassembling the console. Make sure there is no force on the wires.

    You can also choose to not re-assemble the console, just ensure that you have a heatsink on top of the APU and power it correctly.

    Serial Monitor (Actually reading the UART)

    If you want to be fancy you can use a cheap USB Logic Analyzer to view the UART output, but this is a bit much for beginners.

    I suggest using PuTTY to read the UART output: https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html

    Run PuTTY and select Serial, input the correct COM port in the serial line (You can find out what yours is within WIndows Device Manager under Ports (COM & LPT)). In speed put in 115200 which is the baud rate for the PS4 UART.

    Now hit OPEN and move on to the next step!

    Diagnostic

    • Turn on the console.
    • Whatever the UART output stops at is the issue.

    Common Errors

    ERROR:DCT[0/1] is disabled

    The first ram block has a failure. A ram block is a pair of ram modules. It will complain about both of them, even when only one is failing. The ram blocks are 0/1, 2/3, 4/5, 6/7

  • RAM blocks as shown on a PS4 Slim. Also applies to 12xxx fat model.
  • ERROR: main(####) loadBios -8 & SAMU Enter/Leave

    Accompanied with ERROR: loadBios(####) sceSblSlLoadSelf -8, #### or loops the message SAMU Enter and SAMU Leave.

    Your syscon is not decrypting the NOR in both errors. SAMU is responsible for managing keys and decryption.

    Solution: Replace all per-console chips with that from a donor board. Essentially get an entirely new working or partially working console and use it for parts.

    Example Outputs