I converted a Sony Vaio PCG-K25 computer into a Raspberry Pi 3B and Teensy ++2.0 laptop. The circuits in the laptop are listed below and then described in detail in the PDF at my Github repo at https://github.com/thedalles77/Pi_Teensy_Laptop
The Teensy code and the Eagle layout file are also at this Github repo.
1. A Teensy ++2.0 is used to interface the keyboard and touchpad with the Pi via USB. This required a new circuit board to route the keyboard connector to the Teensy I/O pins. A Teensyduino sketch scans the keyboard and touchpad and sends changes to the Pi over USB.
2. The HDMI from the Pi is converted to LVDS for the display by an M.NT68676 video board. The video cable had to be lengthened to reach into the laptop base.
3. The control pad for the M.NT68676 video board was replaced by the Teensy.
4. The Pi boots from a 240GB solid state drive using a SATA to USB cable. The micro SD card has been removed.
5. The laptop Wi-Fi antenna is connected directly to the Pi for improved reception. A connector was added to the Pi that fits the laptop antenna cable.
6. A Real Time Clock and the Teensy are connected to the Pi over the I2C bus.
7. Three separate Buck regulators provide power to the M.NT68676 video board, the Pi, and the 4 USB ports. The regulators were modified so they can be enabled with a control signal.
8. The laptop power switch turns on the regulators and the Teensy turns off the regulators. This is accomplished with a NAND gate latch circuit that controls the regulator enable signal.
9. The laptop LEDs were rewired to show incoming power, regulator power, caps lock, and code debug.
10. The Teensy will reset the Pi if Control-Alt-r is typed or shut down the laptop if Control-Alt-s is typed. These actions can also be initiated by the Pi over the I2C bus.
11. The Pi GPIO signals are brought out the side of the laptop for bread boarding.
12. The Pi audio is cabled to a 3.5mm jack on the side of the laptop for headphones.
13. Audio sent to the M.NT68676 board via HDMI is connected to the laptop speakers.
14. A fan blows over the Pi and another fan blows out the back. Testing shows this gives adequate cooling to the Pi when overclocked at 1300 MHz.
A short YouTube video for this laptop project can be found at https://www.youtube.com/watch?v=Gh3VTcL ... e=youtu.be
I'm still working on battery operation for this laptop but I wanted to share what I had so far.