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Why lighting up LEDs is still exciting!

There’s a bit of a standing joke among the engineers at MLE – that with every new project, the aim is really just to find new and evermore interesting ways to light up an LED (the LED being roughly equivalent in the embedded world to the standard “Hello world” message so beloved of software developers).

Usually it’s a new processor or a complicated communications path that we’re testing out.  Perhaps we’ve design a system where a tagged item moves past an RFID tag detector, causing a microcontroller to notice and then transmit a wireless Zigbee message to another embedded device.  This controller might then pass the message along its power line wires to a central hub, which in turn uploads the data to a remote server via a 3G connection.  And this perhaps then triggers another embedded controller in a completely different country to notice that something really rather interesting has happened, and that it would be polite to let the eagerly-awaiting engineer know…  and how does it do this? – by lighting up an LED, of course!

One of our most recent projects has been using the new PowerPSoC from Cypress Semiconductors with which we can demonstrate some extremely fancy current control over large voltages from one chip.   And what method did we use to show off the PowerPSoC in all its glory? – yep, you guessed it – by lighting up LEDs.

Except in this case, we’ve gone rather more advanced than simply turning a bog-standard LED on and off, and instead are smoothly varying the subtle nuances of a full range of different colours with a control of one part in 65536 (or a resolution of about 0.001%, to put it another way) on each of the red, green and blue (RGB) LED channels.  And since this control is done primarily in hardware embedded within the PowerPSoC itself, the feedback times of the system are incredibly small, ensuring that the device is safe from over-current at all times.

The onboard boost control and power modulation of the PowerPSoC make it ideal for controlling LED architectural lighting , but it would also be suitable for applications such as 3D gyroscopic motor control, solenoid drives and linear actuators too.

Additional benefits of this system include an EMC-friendly PrISM control system (which we’ve demonstrated with the precise dimming control for LEDs) and a 5V regulator built into the silicon - with only a few external components we can run high voltages (over 30V) into the chip.  The PowerPSoC is then able to produce a rail to run the internal core on, as well as a system-wide 5V supply which can be used to power the rest of the circuit, removing the need for external power control circuitry.  The PowerPSoC  is also able to perform the majority of other tasks of a standard PSoC, including CapSense, PGAs, integration to the CyFi wireless system, as well as including the general peripherals found in the majority of other embedded  controllers such as timers, counters and ADCs.  Communications options from the PowerPSoC  include the generic SPI and RS-232 protocols, as well as comms protocols aimed specifically at the lighting markets such as DMX512 and DALI.

In my view, Cypress Semiconductors have really excelled themselves with this processor.  The PowerPSoC allows the engineer to provide outstanding motor control as well as some rather spectacular lighting effects.   Despite not being the biggest or fastest microcontroller the PowerPSoC provides power functionality which cannot be found on any other embedded device – and we like it.
 
By Jon

(PS. Increasingly of course, the LED is not just a means to an end, but is instead the very object of interest itself – we’ve written briefly before about the emergence of LEDs as a low power advanced lighting solution – no longer will the humble LED be consigned to the annals of history as being a mere indicator that something more exciting has happened somewhere else in the world!)

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