Upgrading Firmware of JYETech Scope …and other goodies
Since I purchased the $49 JYETech Scope, several versions of the firmware have been released. The latest enables “20Msample/sec effective sampling rate”. The following is a summary of the steps required to upgrade the firmware:
1- Purchase a USB to TTL converter. I purchased the following converter based on the Silicon Labs CP2102 device at eBay
2- Download and install device driver from Silicon Labs: VCP Driver Kit (VPC is “virtual COM port”)
4- Download the firmware uploading application: AVR Universal Bootloader: JYETech AVRubd link (v4.1). There is a newer version, 4.5 in the web. Both versions work well
5- Download the manual and follow the “using the bootloader instructions”: Link. Use the COM port assigned to the USB-TTL converter. You can easily find out which COM port by examining the device manager or by checking the com ports in the AVRubd with and without the USB-TTL converter plugged in the USB port
6- Connect USB-TTL converter to the scope, following the instructions in the manual (but without connecting the 5V line). The manual instructs connecting the 5V line because the serial port does not provide power whereas USB provides power. Caution: If you connect the 5V line, the scope will power-on without any other power source. It is probably not a good idea to connect the 5V line and also power the scope from an external supply.
Note: I found that in my device, the TxD and RxD labels are flipped, so I connected TxD to RxD and RxD to TxD. You can try either way if the scope does not respond. Also to ensure that the USB-TTL converter is working correctly, you can download Serial Loopback Test to test the device.
7- Continue following the instructions in the manual
Capturing Scope Traces on a PC
JYEShot is a mini application to receive screen captures from the scope. You can use the same USB to TTL converter with the same configuration described above to upload a screen capture to a PC. Here is an example capture
Tip: One of the configuration parameters in the application is the Rx delay (in the menu item settings->timings). I found that with the 30 msec default setting the transfer did not work. Increasing the delay to 50 msec, solved the problem.
Tip: Instead of saving the trace with file->save in the JYEShot application, you can just change the name of the TMP file that is created in the folder where the application resides. This way you can quickly use the file name you wish. Every time you save a trace it will be to a file called “TMP”
Example uses of the oscilloscope for audio applications:
- Measuring the I2S lines: LRCK, MCK and fs, BCK,
- Measuring noise in rotary encoders. Here I used single trigger mode to capture a single change/switch of the rotary encoder. In single trigger mode, the scope will automatically enter HOLD mode after each trace capture.
“Better” USB-TTL converver
I found this other USB-TTL converter on eBay (search for CP2102) which is more versatile than the one I purchased. The one described above has 6 pins (5v, 3.3v, GND, RxD, TxD and RST). The RST pin is to reset the CP2102 device. If you want to use this device to program an Arduino, there is no pin to auto reset the Arduino.
This device exposes the DTR pin which can be used to auto reset the Arduino (start the Arduino bootloader) prior to downloading a new program. Thus this device can be used to program the scope, and also to program an Arduino that does not have a built in USB interface such as a bare-bone Arduino. (Note: I have not tested this device)