Oscilloscope on ODROID-7

ODROID-7 has an expansion port of TTA20 connector.
There is an ADC port which is connected to S5PC110 processor.
We are using the ADC port to make a simple oscilloscope.

Please note the ADC sample rate is only 1Mega samples per sec and it causes very low band width.
But, it is still useful to see any moving/static level of signals on GPIO or audio frequency band.

We could grab SINE wave signal as below picture.

Hardware structure.
– One OPAMP for signal conditioning (Attenuation as well as makes high input impedance)
– One LDO for power supply of OPAMP
– One LED can be controlled by CPU to display status
– This board can work with Odroid-T as well.
– TP1 is signal input and TP2 is reference(ground).

This 20pin TTA connector can be attached to ODROID-7 directly or through debug board.

Schematics of OSC board.

Software structure.
– Modified ADC device driver in Kernel
– JNI parts for inter-connection with Java (We call it NDK from time to time)
– Java application to display signals.

What to do….  (Future improvement)
– Trigger function
– Zoom In/Out with multi-touch pinch input
– Better Horizontal/Vertical scaling
– Math lib for FFT/DCT

We will open the source code within couple of weeks.
I think this is a very nice example to learn how real embedded system can run with Android OS.
It also can be a good text book/reference for beginners.

Thanks,