A DVD Player Hack

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Step 1: Scrapped DVD player parts

Vacuum fluorescent displays (VFD) make any consumer device looking eye-catching, compelling and unusual. A VFD emits a very bright light with high contrast and can support display elements of various colors, some of them are capable of rendering not only seven-segment numerals but characters and even graphical information. VFDs are equally great for anything from professional devices to basic do-it-yourself things. Yet VFDs are rather expensive for small hobby projects and notorious for their non-trivial control as they require voltages higher than just TTL levels, necessity to drive grids in addition to segments or dots and therefore make presence of dedicated VFD controllers highly desirable just to simplify communication with microprocessors.

But what if all this infrastructure already existed, would it be that difficult to combine together something like Arduino controller and VFD? The answer is no, not at all! Most modern DVD players equipped with VFDs and when less reliable mechanical parts (DVD ROM drives) fail devices are simply thrown away. Instead, some electronics could still be reused to give your project a completely new look reducing costs at the same time and saving the environment. In addition to a VFD with controller onboard and a power supply which provides everything with all vital voltage levels there is a bonus – an IR receiver and buttons. VFD controller takes care of refreshing display, handling events from buttons and IR receiver encapsulating whole control into a serial interface and making integration with even primitive controllers very possible, giving in exchange fully functional remotely controlled system.

But enough theory, let’s have a look at a real example. We found a broken DVD player literally lying in the street. Quick test indicated that VFD board and power supply were functional. VFD was 16-segment and therefore capable of displaying not only digits but characters as well. After a few minutes of internet search model name was identified: Philips DVP630

For our experiment we will need a front VFD panel and a power supply board only.

Step 2:

Having the service manual and VFD driver datasheet in front of you significantly simplifies reverse engineering. It took us only a few minutes of googling – and service manual with schematic diagrams were found. After opening up Philips DVP630_632_642 schematic diagram  (please find the file attached below) and looking at page 3 it becomes obvious that the player utilises DP501 HNV-07SS61 display from Samsung which is controlled by HT16512. Then downloading datasheet for HT16512 (please find the attached file below) – it is a VFD driver with 11 segment output lines, 6 grid output lines, 5 segment/grid output lines 4 LED output ports, a control circuit, a display memory and a key scan circuit. Serial data inputs to the HT16512 through a three-serial interface – just what we need!

Returning back to the page 3 of the service manual, checking RB502 connector – there are V-CLK, V-CS, V-DATE to control VFD. Also we will need GND, IR (output from infrared receiver) and +5V. An attentive reader should notice that there is also +5V_STB at RB501 connector. It is 5V standby voltage that is always applied. +5V appears only after pressing either ‘StandBy’ TA501 button on DVD’s front panel or On/Off button on a remote control. The power supply is instructed to activate/deactivate +5V via PCON signal. But in order to wake up the player from a remote control only original RC must be used otherwise IC581 won’t recognise the command. We want to make our device working with ANY type of RC that is why our microcontroller must take responsibility of decoding RC commands and controlling PCON signal.

Please refer to the picture, the hacking points are marked with red ellipses.

DVP630_632_642_sch_.pdf1 MB

HT16512.pdf130 KB

Step 4: VFD Driver Demo

In order to control DP501 HNV-07SS61 VFD in an effortless and efficient manner the following software driver has been implemented. The functionality is encapsulated in HT16512.cpp and HT16512.h files and designed for AVR processors. To drive communication interface the logic uses pinMode and DigitalWrite functions provided by Arduino low level library. Also new HT16512 class inherits Arduino’s Print class to simplify output to display even more. However, despite those Arduino’s dependencies the code might be easily ported to PIC or ARM architectures.

The driver’s logic is subdivided into several groups: initialisation and low-level methods, tests and visual effects, methods for direct access to HT16512 without intermediate buffer and methods for intermediate buffer operations.

We won’t discuss boring details of VFD driver implementation, however, if you are interested, you can refer to this article: http://atmega.magictale.com/853/vfd-driver-demo/

The code below demonstrates how to initialise our VFD driver:

#include <avr/interrupt.h>
#include <util/delay.h>
#include “wiring.h”
#include “HT16512.h”

#define VFD_CS_PIN   15 //PD7
#define VFD_SCLK_PIN 14 //PD6
#define VFD_DATA_PIN 13 //PD5

#define STANDBY_PIN  12 //PD4

HT16512 vfd(VFD_CS_PIN, VFD_SCLK_PIN, VFD_DATA_PIN);    //VFD display

int main(void)
{
pinMode(STANDBY_PIN, OUTPUT);
digitalWrite(STANDBY_PIN, HIGH);

//Enable VFD power supply
digitalWrite(STANDBY_PIN, LOW);
_delay_ms(100);
digitalWrite(STANDBY_PIN, HIGH);

//Initialise VFD tube
vfd.reset();
vfd.addrSetCmd(0);
vfd.clearFrame();
vfd.flipFrame();

sei();

while (1)
{
vfd.testStep()
_delay_ms(200);
}
}

As you can see, apart from VFD_CS_PIN, VFD_SCLK_PIN, VFD_DATA_PIN pins that are dedicated to VFD communication there is also STANDBY_PIN pin that simulates POWER button and instructs to switch +5V power rail on.

Let’s get down to the hardware part. In this demo we will be using Freeduino board. In total we would need 4 (four) signal wires to connect it to the VFD panel. Of course, we will also need GND and +5V power rail.

Here is the signal mapping table between Freeduino board and VFD panel (please also refer to DVP630 Schematic Diagram):

And the video demonstrates the result: Freeduino board running VFDDemo, connected to the VFD panel and power supply from broken Philips DVP 630.

For more detail: A DVD Player Hack