Sahil Shah
3 min read

SystemHUD

  • electronics
  • 3d printing
  • rainmeter
  • fusion 360
A small screen mounted low inside a dark PC case behind the glass side panel, showing CPU and GPU temperatures for an i7-12700K and an RTX 3070 Ti.

Usually, junk mail is just that: junk, but this time it was a bit more. We received a thick brochure in the mail. This odd brochure had an LCD screen inside it that played a video when the mail was opened. Instead of just throwing it out, I decided to give this horrible waste of money destined to be e-waste a new purpose in life as a small screen in my PC case that can track system information.

Physical Supplies

Software

  • Rainmeter + Custom Programmed Skin
  • HWINFO
  • Fusion 360 or similar CAD software

Step 1: Tearing Down the Brochure

The video mailer I got was similar to the one shown here:

A folded blue video brochure standing open, with printed text on the left panel and a small video screen with playback buttons on the right panel.

After tearing down the brochure, I recovered this LCD Display:

A bare rectangular LCD panel on a wooden table, with an orange flexible ribbon cable coming off one side.

It is very similar to the one that Adafruit sells with a touchscreen: https://www.adafruit.com/product/1591

Product photo of a 4.3 inch TFT display with a white frame and an orange flex cable, on a dark background.

Step 2: Initial Testing

First I took the display and put it into the case to find a spot where it fit in and looked good.

The bare LCD panel propped up on the lower shroud inside a black PC case, with its ribbon cable draped over the top.

The original board allowed me to upload my own video and play it on loop so, of course, I had to do this:

The LCD inside the PC case seen through the glass side panel, playing a colorful video, next to an Intel Core i7 sticker.

Step 3: Designing an Enclosure

My PC is built in the Fractal Design Meshify 2 Compact Case and so the screen enclosure was made to fit that.

A dimensioned CAD sketch of the display outline, 105 mm wide and 68 mm tall, with small border measurements.

A CAD model of the LCD panel with its flex cable hanging below it.

A CAD render of the black enclosure from the back, showing an angled top lip and a rectangular cutout for the cable.

A CAD render of the black enclosure from the back at another angle, with a pocket for the extension board below the cable cutout.

A CAD render of the enclosure fitted to the case shroud, with the display frame highlighted in blue around the screen.

A CAD render of the finished enclosure on the case shroud, with the screen showing CPU and GPU temperatures.

The screen is 3.05 mm thick

On the back of the LCD, I added a spot to house the extension board for the 40-pin ribbon cable

Step 4: Getting the Decoder Ready

Out of the box, the HDMI decoder was not ready to use just yet, there are two things I had to do. First, I had to change the backlight brightness.

Close-up of the blue TFP401 decoder board with red arrows pointing to two solder jumpers, labeled base 25mA, plus 25mA and plus 100mA.

There are these two jumpers that can be used to change the backlight current. Mine is probably 50mA so I soldiered the connection across the first one.

Macro photo of the decoder board showing one jumper bridged with solder and the other left open.

This will provide the LCD backlight 25+25=50mA of current.

Next, I had to soldier the pin headers to the EDID EPROM pads.

Close-up of the decoder board with the four EDID EPROM pads, labeled 5V, GND, SCL and SDA, highlighted.

These pads need to be connected to an Arduino with jumper cables to reprogram the EDID.

The underside of the blue decoder board on a wooden table, with four header pins soldered through the EDID pads.

The top of the decoder board with four header pins soldered to the EDID EPROM pads, next to the HDMI port.

Step 5: Reprogramming The EDID EPROM

The EDID is the part of the decoder that tells the computer the size and capabilities of the display connected. By default, it is configured for an 800x480 display. Since mine is 480x272, I used a slightly modified Arduino script from the Adafruit website to change it.

#include <Wire.h> //I2C library

/* 480x272 @ 25mhz */

const uint8_t PROGMEM eepromdat[128] = {
0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x04, 0x81, 0x43, 0x00, 0x01, 0x00, 0x00, 0x00,
0x0C, 0x17, 0x01, 0x03, 0x81, 0x0A, 0x06, 0x78, 0x8A, 0xA5, 0x8E, 0xA6, 0x54, 0x4A, 0x9C, 0x26,
0x12, 0x45, 0x46, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0xC4, 0x09, 0xE0, 0x33, 0x10, 0x10, 0x14, 0x10, 0x08, 0x05,
0x4A, 0x00, 0x5F, 0x36, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00, 0xFC, 0x00, 0x41, 0x44, 0x41,
0x46, 0x52, 0x55, 0x49, 0x54, 0x20, 0x34, 0x33, 0x20, 0x20, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42
};

/* Adafruit breakout @ 800x480 !
const uint8_t PROGMEM eepromdat[128] = {
0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x04, 0x81, 0x04, 0x00, 0x01, 0x00, 0x00, 0x00,
0x01, 0x11, 0x01, 0x03, 0x80, 0x0F, 0x0A, 0x00, 0x0A, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x80, 0x0C, 0x20, 0x80, 0x30, 0xE0, 0x2D, 0x10, 0x28, 0x30,
0xD3, 0x00, 0x6C, 0x44, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x17,
};
*/

// I2C eeprom dumper
byte i2c_eeprom_read_byte(uint8_t deviceaddress, uint16_t eeaddress );

#define EEPROMSIZE 256UL  // 0.5 Kb
#define ADDRESS_SIZE 8

byte i2c_eeprom_read_byte(uint8_t deviceaddress, uint16_t eeaddress ) {
    byte rdata = 0xFF;
#if (ADDRESS_SIZE == 16)
    Wire.beginTransmission(deviceaddress);
    Wire.write((eeaddress >> 8)); // MSB
#else
    //deviceaddress |= (eeaddress >> 8);
    Wire.beginTransmission(deviceaddress); // MSB
#endif
    Wire.write(eeaddress); // LSB
    Wire.endTransmission();
    Wire.requestFrom(deviceaddress, (uint8_t)1);
    while (!Wire.available());
    rdata = Wire.read();
    return rdata;
}

void i2c_eeprom_write_byte(uint8_t deviceaddress, uint16_t eeaddress, byte data ) {
#if (ADDRESS_SIZE == 16)
    Wire.beginTransmission(deviceaddress);
    Wire.write((eeaddress >> 8)); // MSB
#else
    //deviceaddress |= (eeaddress >> 8);
    Wire.beginTransmission(deviceaddress); // MSB
#endif
    Wire.write((byte)eeaddress); // LSB
    Wire.write((byte)data);
    Wire.endTransmission();
}

void setup() {
  Wire.begin(); // initialise the connection
  Serial.begin(9600);
  Serial.println(F("EEPROM WRITER"));
  Serial.print(F("EEPROM data size: "));
  Serial.println(sizeof(eepromdat));
  Serial.println(F("Hit any key & return to start"));
  while (!Serial.available());
  byte b;
  Serial.println("Starting");
  for (uint16_t addr = 0; addr < EEPROMSIZE; addr++) {
    if (addr < sizeof(eepromdat)) {
      b = pgm_read_byte(eepromdat+addr);
    } else {
      b = 0xFF;
    }
     i2c_eeprom_write_byte(0x50, addr, b);
     delay(5);
     if ((addr % 32) == 0)
       Serial.println();
     Serial.print("0x");
     if (b < 0x10) Serial.print('0');
     Serial.print(b, HEX); //print content to serial port
     Serial.print(", ");
  }
  Serial.println("\n\r========\n\rFinished!");
  for (uint16_t addr = 0; addr < EEPROMSIZE; addr++) {
    if (addr < sizeof(eepromdat)) {
      b = pgm_read_byte(eepromdat+addr);
    } else {
      b = 0xFF;
    }
    uint8_t d =  i2c_eeprom_read_byte(0x50, addr);
    if ((addr % 32) == 0)
      Serial.println();
    Serial.print("0x");
    if (d < 0x10) Serial.print('0');
    Serial.print(d, HEX); //print content to serial port
    Serial.print(", ");

    if (b != d) {
       Serial.print(F("verification failed at 0x")); Serial.println(addr);
       while (1);
     }
  }
  Serial.println(F("\n\r\n\rVerified!"));
}

void loop() {
}

Step 6: Creating The Rainmeter Skin

I created a Rainmeter skin from the ground up to show my system vitals in a clean, modern UI.

The Rainmeter skin under load, showing the i7-12700K at 60 degrees and the RTX 3070 Ti at 61 degrees with ring gauges, plus RAM and vRAM bars.

The Rainmeter skin with the CPU at 80 degrees and 99 percent load, highlighted with a red ring, and the GPU at 49 degrees.

The Rainmeter skin at light load, with the CPU at 52 degrees, the GPU at 42 degrees, and RAM and vRAM bars between them.

The Rainmeter skin with the CPU at 44 degrees and the GPU at 45 degrees on a pink and blue background.

[Extra Side Project]

The bottom fan on the front blows air into the cable “basement” where it does nothing and is wasted. To solve this, I created a part that directs air into the bottom of the GPU to improve cooling by a slight amount.

The PC case in daylight through the glass side panel, with the system monitor screen mounted on the lower shroud showing CPU and GPU temperatures.

The same PC case in the dark, lit blue inside, with the system monitor screen glowing on the lower shroud.

Final Remarks

Transforming e-waste into a super useful HUD for my PC was a fun experience and taught me a lot about modern electronics while researching how the HDMI signal works and how to make it work with the 40-pin LCD cable.

Resources