Actrino X2 In The Design Pipeline

The fact that this blog hasn’t been updated in a while is in part attributable to the fact that I’ve been busy updating everyone else’s blogs –I’m the cobbler whose children have no shoes. So just what is Ken up to these days? I’ve been busy, let me tell ya. I’ll play catch up with a flurry of blog posts, here’s the first one…

Through mid-summer I concentrated on building up a few more Actrino X1 prototypes and shepherding the design towards it’s next incarnation.  I went to quite a few meetups and tech gatherings and got feedback from several trusted engineering friends and finally decided on some new features and formats for the platform.  I’ve been distracted by other projects the last couple of months but I’m getting back to laying traces recently. The schematic for the X2 version is complete, board layout is maybe 75% done, and I hope to have some prototypes together by the end of the year. Here’s a 3D rendering of the design at the moment:



You might notice a few changes from the X1 version. Where the X1 used an Atmel AtMega328 microcontroller chip in a DIP package, the X2 upgrades to an ATmega640/2560 pinout in a TQFP 100-pin surface-mount package. You should NEVER run out of I/O pins — OR MEMORY — on this board!

The X2 also includes some extra power output transistors, which upgrade the original 4-channel current sink output to a fancy precision DC current and PWM-controlled dual H-Bridge that can drive loads in the sub-100W range in some very clever ways. There are also copious jumper pins to provide a plethora of operating options, including current gains and error/alarm signals per output channel. The power supply circuitry is completely redesigned, with options for a back-up DC supply input, sophisticated real-time current monitoring and overload shutdown for both 5V and load power, and a replaceable microfuse socket for fail-safe over-current protection.

Click BoardsPerhaps the biggest change is the adoption of the Click™ board format. The new X2 design provides four mikroBUS™ sockets that can accomodate the more than 50 expansion functions perofrmed by the ever-expanding line of Click boards. And the format is perfect for developing custom functions as well. Developed by MikroElektronika a few years ago to address their need for a standardized “breakout board” format for various I/O and interface chips, the mikroBUS™ form factor provides just the right balance between small size and having sufficient and rational I/O per breakout function (I2C, SPI, TTL serial, interrupt, analog, reset, and 3.3 and 5VDC power pins). Since the ATmega640/2560 chips have four serial ports, each mikroBUS™ socket will have it’s own TX and RX signals.

Now MikroElektronika makes some cool stuff but it is not directly “Arduino-compatible”. But the cool thing is, most of the chips used on these boards are the same as those used on other breakouts by AdaFruit, SparkFun, and others, so there are Arduino libraries floating around for most all of the Click chips.  And it’s a much more svelte form factor than Arduino’s shield format. I’ve played with some of the Click boards on the breadboard and they’re pretty nifty, so I’m looking forward to using them soon on the Actrino X2. mikroBUS™ and Actrino together are bound to be a powerful and versatile platform for open source research apparatus and lab instruments — stay tuned!


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