Saturday, 25 April 2015

Si5351 Shield Production PCBs

After a long gestation, the production version of the Kanga / m0xpd Si5351 Shield PCBs is now back from the delivery room...

I just finished populating the first full board and - like all proud fathers - I'm pretty pleased with it...

The board now uses the full Arduino 1.0 pin-out, so logic voltage level selection is automatic, being set by the host board through the "IOREF" pin.

Whilst this board is offered in the format of an Arduino shield, it calls upon very few of the resources of the Arduino and can run perfectly well within another computing framework. It has, for example, already been demonstrated with a Raspberry Pi and can be controlled by any system capable of generating the necessary I2C commands.

As has been explained in previous posts describing "engineering" versions of the shield, the "m0xpd RF Bus", first seen on the Kanga / m0xpd DDS Shield,  has been enhanced to support the three RF outputs of the Si5351, whilst retaining backwards compatibility with the original RF Bus. This allows the Kanga / m0xpd Tx shield and the new Rx shield to be used with this new RF generator.

In addition to quadrature square wave outputs derived from CLK2 (Q and I outputs were also provided on the DDS Shield) the new shield also presents the complements of these quadrature square waves on the RF bus to make it easier to drive certain implementations of "Tayloe" detectors.

The new shield  also includes two of Pete Juliano, n6qw's "Afterburner" amplifiers, which are seen on the annotated picture below...

The Si5351 alone only produces about 0.7 V into 50 Ohms. The addition of Pete's reheat livens things up nicely (to leave a diode in no doubt as to which way is up!)...

This - remember - is provided on two independent channels, derived from the Si5351's CLK0 and CLK1, and these amplified outputs are transformer isolated (see the binocular cores near the SMA sockets).

Kanga UK are planning to launch this new shield at the Four Days in May event in Dayton, Ohio where it will be supported by plenty of software application examples - including for my Parallel IF scheme.

Even if you don't get one of these shields, do yourself a favour and check out the Si5351 - you'll be glad you did,

...-.- de m0xpd

Friday, 10 April 2015

New Receiver Shield

The new Kanga / m0xpd Rx Shield is here...

I stuffed the first production PCB yesterday evening and had it running on 40 in a matter of moments!

There are no great surprises from the original "Sudden Rx Shield" from way back in 2013 - but I've done some tailoring of the audio frequency response and we've been forced to change to an SMD package on the SA602 due to supply issues.

The shield retains the external audio processing loop, which allows the introduction of everything from volume controls to filters and audio processors and includes software-controlled Rx muting.

You can see the new shield on the Kanga stand at the NARSA show, where it is being launched this Sunday

in the luxurious surroundings of the Norbreck Castle Hotel in Blackpool.

I was going to say "Sunny Blackpool", but they tell me our recent spell of settled weather is going to change this evening, so all bets are off.

See you on Sunday!

...-.- de m0xpd

Wednesday, 1 April 2015

ANOTHER Raspberry Pi

Single board computers are coming thick and fast at the moment...

No sooner than the Arduino ZERO has just been released, with its interesting ARM core processor...

this morning saw the appearance of the brand-new, "Bitchin' Fast" Raspberry Pi Model C...

This is crazy - I've only just closed my wallet from ordering the last revision and reported its first use on these pages - I can hardly keep up with this blistering rate of innovation!

Still - I mustn't complain - apart from the new, racy language (the phrase "Bitchin' Fast" is right there next to the network port - see my red box on the photo above), the changes move the RPi C very much in MY direction.

See all those header pins - they're all I/O - from an ATmega328 used (one supposes) as some kind of I/O processor - shades of Arduino creeping into the RPi camp here.

This is all - of course - nonsense (except for the Arduino ZERO - which is for real).

It is - if you check the date - April fool's day.

Several folks with Jam on their hands have perpetrated a particularly well-executed gag - in a similar league to the great BBC spaghetti joke of 1957...

Nice one guys!

But please don't miss the meaning in your madness; it would be nice to see the RPi continue to grow in a direction which encourages and facilitates Physical Computing, as well as just growing in pure computational grunt.

Happy days, to fools everywhere.

...-.- de m0xpd