The first prototype ZonCoffee v3 boards have arrived and are nearly up and running. I’m currently porting the code over to Arduino 1.0, as this board uses the Arduino Leonardo bootloader. Read on past the break for more info on the new board.

v3 Features:

• 6-Pin AUX port allows use of parallel LCD or custom expansion
• Supports SparkFun serial LCD
• USB port emulates virtual serial port for logging and loading new firmware
• All ports broken out to screw terminals
• Power via USB or external independent power source
• MAX6675-compatible footprint (also supports Maxim-IC’s newer chips)
• 6-Pin ICSP header for flashing custom bootloaders
• Main power and USB power LED indicators

This PCB includes connectors for external power, a SparkFun serial LCD, a pusbutton encoder, a thermocouple probe, a solid-state relay, and an auxiliary port. The auxiliary port pins are all connected to the ADC, allowing additional analog or digital IO for expansion. Note that the logo is silkscreened backwards, which is the only (thankfully superficial!) problem I have encountered with my board so far.

The PCB is populated with an ATMEGA32u4, an 8-bit Automotive-grade microcontroller from Atmel that features a USB interface as well as USART and SPI. This board takes advantage of USART for the SparkFun serial LCD, SPI for interfacing with the MAX6675 thermocouple interface chip, and USB for logging and updating firmware with a computer.  All parts on the PCB aside from headers are surface-mount, allowing a very compact design. For permanent installation, screw terminals can be depopulated and wires soldered directly to the board (except for the thermocouple leads, which cannot be soldered).

I have fully populated and tested two of these PCBs so far, and everything is completely functional. There are still a few software quirks from porting my original code to Arduino 1.0, but the boards themselves are fully functional. After a bit of tweaking with the encoder library and creating a drop-in library for attaching a HD44780 LCD to the auxiliary port, this design should be completely usable. I have one board up and running on my espresso machine for both use and development, and I also have a board attached to my roaster (modified Poppery I) that I will be using to experiment with ramping the setpoint for temperature-controlled coffee roasting.

Want to get one?

I’m planning on making a small beta run of boards in the coming months. Drop me an email or a comment below if you’re interested. I haven’t priced the beta boards out yet, but they will be available at a reduced price as long as you’re willing to provide a bit of feedback on the system.

Update (2/9/12)

Development on ZonCoffee has been a bit slow lately, as I’ve been working on a more time-critical project. Coincidentally, the project I’ve been working on also uses the ATMega32u4 on a much larger scale, so I can backport some fixes to the Arduino Leonardo specification to this project. I should be able to resume work on this project in the next couple of weeks.

A few people have asked some questions about the EC155 tamper size, replacement frothing wands, etc. I’ll keep updating this page with answers to common questions.

Tamper Size

The EC155 uses a 52mm tamper (about 2 inches), and the guys over at coffeegeek recommend the RSVP Terry’s Tamper, which weighs in at a mere $6.95. If you’re looking for something a bit nicer, check out Coffee Compliments’ aluminum tamper ($17). They also offer all of their other tampers in the 52mm size, although they are all upwards of $17.

Frothing Wand

I’ve been looking around for a suitable replacement tip and/or wand for the EC155, and I’ve stumbled on a decent solution (thanks to people in this thread). Head over to your local hardware store or Home Depot and purchase a M6 x 1.0 acorn nut (stainless steel). Drill a 1/16″ hole in the tip, I drilled from the inside of the nut using a drill press and some 3-in-one. After drilling the hole, get a larger bit and drill from the other side  to remove burrs. Be sure to wash thoroughly before use! The tip seems to work quite well, although I think a smaller hole could improve performance.

Feel free to leave a comment if you’ve found a tip or wand that fits. For more information, check out this thread on coffeegeek.

Frothing Pitcher

I’ve found that a 12oz pitcher seems to work best size-wise with the EC155. The 12oz pitcher is also short enough to allow milk frothing with an acorn nut tip, without a steam wand extension. This pitcher (~$14)  is similar to the one I use. There are also cheaper options, but it’s nice to have a sturdy pitcher with a spout.

You can also get a cheap ($10) or more expensive ($14) frothing thermometer, or you can just use a cheap meat thermometer (which works well, although it won’t clip on your pitcher nicely).

Baskets

I’ve been unable to find much information about usable baskets for the EC155, but some people have had luck with some of the baskets listed below.

• Delonghi 606348 [amazon] – Fits, but results aren’t great (see androidmert’s comment)
• Delonghi 607706 [ereplacementparts] – Fits, but is quite large
• Krups MS-090716 [hard to find] – Fits

Portafilter/Basket Dimensions

I made the following measurements with digital calipers, so they should be fairly accurate:

• Portafilter inner diameter: 54.6mm at top, narrows to 51.2mm at bottom
• Stock double basket
  • Outer diameter: 54.0mm at widest point, narrowing to 49.0mm
  • Inner diameter: 52.8mm

Shot Glasses/Carafes

Since the EC155 has very little clearance under the portafilter, you can’t pull shots into a mug (unless you remove the drip tray, which is quite awkward). These double-walled thermo-glasses work very well, but any vessel shorter than the 2″ will work just fine.