Shruti Hacking - Radel Nano Dx

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Introduction

Step by step instruction on how to digitally hack the Radel Nano Dx Shruti box (exact Version see picture below).

RadelNanoDx.jpg

Radel Electronics Pvt. Ltd. is the pioneer in the field of electronic musical instruments for Indian music. Radel started in a garage in 1979 and has today state-of-the-art facilities for designing and manufacturing a wide range of Digital Indian musical instruments. Time to hack one of their products I would say.

The hack is based on a careful reverse engineering of the devices main electronic board. The reverse engineering was pretty straight forward thanks to the careful design the Radel engineers made. Most components are SMD and labeled. Here the PCB and the schematic that goes with it:

NanoDxMainPCB.jpg
Main electronic PCB

NanoDxSchematic.jpg
Reverse Engineered Schematics

Circuit Description

Here the main functions of the circuit (separated by colors):

NanoDxBloc.jpg

Red: The heart, the AVR ATTINY 2314-20 micro controller Get the data-sheet here: www.atmel.com/Images/doc2543.pdf You can reprogramm this chip easily using the programming adapter (color orange, BP1) and the 5V connector (BP2). Unfortunately I could not read the original code from the box.

Then there is the audio out part (green). It consists of 4 pins from the conroller combined togehter with the capacitors C3-C6 and amplifierd and filtered by a integrated circuit (light green, IC). The 4 pins are the ports PD0, PD1, PD2 and PD5 (suprisingly to me no PWM pins).

The interface on the front panel is made up from the 7 segment display (pink), the 4 push buttons (brown) and two leds. You can read the switches through port PB0, PB1, PB2 and PB3. To control the display ports PB0-PB7 (each segement individually) The two LEDs are PD3 and PD4.

The whole curcuit is power by a 7805 voltage regulator (blue) CN1 is the speaker and power connection.


Step by step hacking instruction

Now if you have got one of these beatiful boxes at hand and want to reprogramm it, here the instruction. You will need an kind of AVR prgrammer. I used the AVRISP mkII and avrdude.


NanoDxBox.jpg
This is the box from back side view

NanoDxOpening.jpg
There are 3 screws you want to remove to get inside. One screw is hidden by a sticker (see picture)

NanoDxInside.jpg
This is the inside of the box. Nice and big speaker, speparete power supply, main board combind with front panel.

NanoDxPower.jpg
Now I suggest to remove the power circuit to avoid electric shock when playing with the box. You can also put batteries in of course (and not connect the power cord).

NanoDxExternalPower.jpg
This is how you can power the circuit with any 9V power supply. All wires are with nice connectors.

NanoDxProgrammingAdapter.jpg
Finaly connect the programming adapter. You may need a adaptor cable to fit your programmer. The pin out on the board is as follows:

NanoDxPinOut.png


Now you are ready to reprogram your Radel Nano Dx. Upload any compiled hex file as you would for any AVR controller. (see here: http://www.youtube.com/watch?v=YtTpUbnct6s&feature=relmfu) The chip is a AVR ATTINY 2314 (-20) and you do not need to program or change any fuses since they are already ok.


Sample Code