Optiplower

Optiplower

Dell Optiplex Power supply experiments.

I want to run a Dell Optiplex 3050 Micro off an industrial 24Vdc supply. Two issues:

1. The Dell takes 19.5v
2. It will refuse to clock above 800MHz if it can't communicate with the charger to check how much power it can provide.

This project aims to solve both by incorporating:

1. A 5A DCDC converter to give 19.5v from 24v input
2. Either an ATTiny85 or a DS2502 to communicate with the mainboard and spoof it into thinking it has a 65W PSU attached.

Onto a single, tiny PCB that can be hidden away inside the Dell.

References:

• https://github.com/KivApple/dell-charger-emulator
• https://github.com/garyStofer/DS2502_DELL_PS
• https://github.com/timothyjager/DellPSU
• https://www.instructables.com/Embedded-EEPROM-Into-DELL-Laptop-for-Charger-Ident/
• https://github.com/HclX/DELL_POWER_SPOOFER
• https://blog.project-insanity.org/2020/05/25/hardware-fix-for-dell-ac-power-adapter-could-not-be-determined/
• Among others

Please use KiCAD 7 to open the board files. The PSU uses JLC/LCSC-sourcable parts if you'd like to build your own.

DigiSpark ATTiny85 devboard LED is connected to PB0

Connection

The output connector is designed for a 5-way 1.27mm pitch ribbon cable. The 5 pins mirror the layout of the pins on the barrel jack PCB connector.

Sample dumps

• DELL00AC090195046CN09T (90w) from https://github.com/garyStofer/DS2502_DELL_PS/blob/master/DS2502_DELL_PS.ino or DELL00AC090195046CN09T2157161543835EAL03 with checksum
• "DELL00AC045195023CN0CDF577243865Q27F2A05=\x94" (45w)

Firmware setup

Uses Arduino CLI

curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh

Programming

You'll need to edit the memory variable in ds2502-emulator/src/DS2502.h to change how the charger identifies.

cd ds2502-emulator

make

make program

make fuses

Works with ATTiny25-10SSU, but can be made to target ATTiny85, etc by modifying the AVRDUDE_MCU? line in ./ds2502-emulator/Makefile along with the fqbn... line in ./ds2502-emulator/sketch.yaml.

Burning bootloader issues

Don't actually need to use the bootloader - I can use the USBASP directly. This section is just left here as a note.

Arduino IDE 2.x, "burn bootloader" with usbasp programmer selected.

Need to swap out programmer for the one on the system or various lib versions won't match, e.g.

error while loading shared libraries: libtinfo.so.5: cannot open shared object file: No such file or directory

E.g.

mv /home/james/.arduino15/packages/arduino/tools/avrdude/6.0.1-arduino5/bin/avrdude /home/james/.arduino15/packages/arduino/tools/avrdude/6.0.1-arduino5/bin/avrdude_old
ln -s $(which avrdude) /home/james/.arduino15/packages/arduino/tools/avrdude/6.0.1-arduino5/bin/avrdude