Compiling and Flashing Artemis Watch Firmware

Download and Install ESP-IDF 5.1.6

The Espressif compiler takes all the individual files and packs them into a binary file that can be flashed to the Artemis Watch.

When I tried the latest version of the compiler, it didn't work with the Artemis source.  The Artemis GitHub page specifies version 5.1, so I downloaded the 5.1.6 installer from https://dl.espressif.com/dl/esp-idf/?idf=4.4

After installing, you can open ESP-IDF in a command prompt window:

It might look a bit daunting, but you only need two commands most of the time.

  To compile a project, go to the project folder and type idf.py build

  Once the build process is complete, plug your watch into your computer and type idf.py flash

Download and Unzip the Artemis Source Code

Go to the Artemis GitHub page (https://github.com/CircuitMess/GC_Artemis-Firmware) and click the latest release on the right-hand side:

Download the zip file and unzip it into the ESP-IDF "examples" folder:

You can't build the firmware yet as it requires some extra files from other GitHub pages.  The "components" and "lib" folders have links to these external projects:

There should be a way to get these linked libraries to download automatically with a GitHub tool, but I haven't been able to make it work.  Any suggestions in the comments would be welcome!

What you can do is click each of these links, then download the zip for each project:

You should download the versions that are linked, rather than looking for the latest release, to ensure everything is compatible.

Unzip the contents of each zip file into the relevant subfolders of the Artemis firmware folder:

It's necessary to rename the "JPEGDEC" folder to "jpegdec" as the compiler seems to be looking for a lower-case name.

Compile the Firmware

In your ESP-IDF command prompt window, go to the Artemis firmware folder and type idf.py build

Even with the right versions of everything, you'll still see some warnings, but as long as the process doesn't stop you can ignore these:

If the build is successful, you'll see a message telling you to run the flash command:

You shouldn't have to worry about specifying the port number unless you have multiple devices plugged in at once, just run idf.py flash

When it finishes flashing, your watch will reboot and you can unplug it!

FX Audio D802C - Unboxing and Setup

I've been using a cheap amplifier from Jaycar ( http://www.jaycar.com.au/Sight-%26-Sound---Home/Home-Amplifiers-%26-Accessories/Modular-Amplifiers/Low-Cost-Mains-Powered-Stereo-Amplifier/p/AA0472 ) on my work PC for about 10 years now, and while it worked it's never sounded that great and has a fair bit of background hum.

Looking online for a replacement, I spotted the D802C on AliExpress: http://www.aliexpress.com/item/FEIXIANG-FX-AUDIO-pure-digital-amplifier-D802C-remote-USB-optical-coaxial-Bluetooth-AUX-input-80W-2/32428321269.html

Not just an amplifier, it's also a USB DAC and a Bluetooth receiver, so it should be able to talk to anything I get in the foreseeable future.

I took the plunge and ordered one.  A couple of weeks later the postman brought this plain-looking box to the door:

I couldn't find much English-language info about this device online, so I thought I'd do a quick write-up on setting it up.

Inside, you get a USB A-to-B cable:

a tiny remote control (with no battery so I haven't tried using it yet):

and this fairly large power brick:

5 amps at 32 volts should make 160 watts, so the claimed 80 watts per channel may not be as unlikely as I suspected.

The included power cord has a European 2-pin plug, but you should have a figure-8 cord sitting in a drawer somewhere anyway:

An absolute bevy of ports on the back:

From left-to-right you have RCA analogue inputs, the RF fitting for the included Bluetooth antenna, optical & coax SPDIF, USB input and speaker connectors with screw-down binding posts.

After hooking up the speakers and power cable, I plugged in the USB and it was picked up and installed automatically by Windows 10:

I set the new device to default output:

The "Advanced" tab lets you select the output sample rate, up to 192kHz in 16-bit or 96kHz in 24-bit:

The display on the front confirms the new sample rate:

I don't know if it's actually putting out 160 watts, but it definitely gets loud!  My little bookshelf speakers were making more noise than I thought they were capable of, without any distortion.

The default bass setting (+14) is too high, but otherwise it works perfectly out of the box.  Bluetooth paired with my phone with no issues.  I'd definitely recommend this for anyone who wants to get better sound from their PC than the usual powered speaker sets.