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Project 2 - JYETech DSO 062

 
I've had this little kit sitting in a box for over a year, and needed an oscilloscope on a couple of occasions for testing and measuring stuff, so I thought I'd get around to putting it together finally.
The kit itself comes from JYETech, a Chinese company that produce a number of useful and very low cost kits for hobbyists and students. 
While not being lab quality accurate, or giving a huge range of features, they do offer the basics and cost a fraction of the price of laboratory standard kit like Agilent and Tektronix for example.
  






The kit itself is nicely packaged and comes with all the SMD components already fitted, leaving just the through-hole components to fit.
 I've included my customary build pictures here to show the assembly process - as far as kits go, this one is very straightforward, and once the correct instructions are located on the website (there are several models and each one has it's own set of instructions) putting it together takes around two hours.

If you're going to build on of these (I bought mine from RoboSavvy in the UK), make sure you visit the JYETech site, and get not only the assembly instructions but also the parts list - you won't be able to assemble without this as this is where you will find the component placement information to match up on the boards silk screen.





Here's a quick run down of the specification:

Features:

  • Features

    Maximum equivalent-time sampling rate (repetitive signal) - 20MSa/s
    Maximum real-time sampling rate - 2MSa/s
    Resolution - 8 bits
    Record length - 256 bytes
    Analog bandwidth - 1MHz
    Vertical sensitivity - 100mV/Div - 5V/Div
    Vertical position adjustable with indicator
    Input impedance - 1M ohm
    Max input voltage - 50Vpk (1x probe) [500Vpk for 10x probe]
    DC/AC/GND coupling
    Horizontal - 0.5us/Div - 10m(minute)/Div
    Auto/Normal/Single trig modes
    Rising/Falling edge trigger
    External trig available
    Trigger output is available, which makes it possible to cascade scopes to do multi-channel capture.
    Trigger level adjustable with indicator
    Hold/run feature
    Save/recall up to 6 captures
    FFT function available - size of 256 points and 512 points selectable, sampling rate of 1Ksps to 2Msps selectable
    Transfer screen to PC as bitmap file via serial connection
    Built-in 500Hz/5Vpp test signal
    Frequency Meter (For TTL level input signal)
    Auto switching between Oscilloscope Mode and Frequency Meter Mode
    9V DC power supply
    Dimension: 110mm X 65mm X 25mm (without case)
    Weight: 125 gram (not including probe and power adapter)

Dimensions:

  • 110x65x25mm
  • Weight: 70g
 The next step is to upgrade the firmware, which will give FFT (Fast Fourier Transform) functionality, and also cure slow button response on the device when it's in certain modes. For this I'm going to need an AVR ISP programmer - out with the soldering iron again!

UPDATE: I'll blog the ISP programmer in its own section, but I just wanted to update here to say that the latest firmware is very good - device response is now almost instantaneous, and all the new functions seem to work fine. I need to sense check this against a calibrated source before I can throw this in the toolbox (yep it'll run from a 9v battery!) but all in all I'm quite pleased :)

A few words about updating the firmware - depending on the ISP programmer you use, your commands might be different from what I'll show below, however I couldn't find anything specific to my setup here online, so kinda felt my way.

In order to upgrade the firmware, you'll need to first download the latest version from JYETech - it hasn't been updated in a while, so I guess this is the final version > Here.

You'll also need an AVR ISP programmer, and AVRDude installed.

Attach your ISP programmer to the standard 10 pin MCU programming port, and attach the ISP programmer to USB. You may find, like I did, that if you power the scope after this, the programmer will start to give errors when you command it to do anything. I got around this by NOT powering the scope with mains, but by enabling the 5V internal power shunt on the ISP programmer itself. This will allow both the programmer and the device being programmed to have 5V to run from straight from USB.

Assuming you are using an ATTiny type of programmer (mine is the Adafruit USBTiny V2), the command required, and output should look something like this:



There's a great explanation of the AVRDude command set here. The key parameters that you need to flash this device are:

-c <programmer chip type> (usbtiny in my case)
-p <part number> (m64 for ATMEGA64) destination part
-U <memory type> 

The command I used to flash the DSO is: avrdude -c usbtiny -p m64 -U flash:w:<firmware HEX file>

The -U function allows r/w/v (read/write/verify) options - see the explanation on the link above. It's also worth noting that unless you specify otherwise, AVRDude will verify automatically after a write.


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