RoadTest: TI Piccolo Multi-DC/DC Color LED Kit
Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?:
What were the biggest problems encountered?:
Thanks to element14 and Texas Instruments for giving me the privilege and opportunity to Road Test the Piccolo Multi-DC/DC Color LED Kit (Multi-DC for short).
Hopefully the editor will allow me to add comments as I am road testing. (I've had all sorts of dickie problems and performance issues with this text editor.)
I apologise for my banter but I find it the best way to convey information in this style blog format.
The kit arrived with in three or so days after being notified. I had absolutely no preconceived ideas of what the kit contained and was not expecting it to be such a large box.
The packaging this kit is very well presented with a glossy box and custom foam inserts that rivals any well arranged tool drawer. [The TI Marketing department done an excellent job!]
In it there's a memory stick, the Multi-DC base board, Piccolo F28027 controlCARD DIMM, power supply, LED panel, diffuser, USB cable, and Getting Started documentation.
My cat loves the element14 box that the kit was packed.
[Oh good! I can continue editing where I left off!]
The kit is designed to show how the F28027 can be easily incorporated into commerically releaseable products based on TI hardware and software.
It demonstrates TI's commitment to Rapid Prototyping to minimise the engineering effort for releasing products to market for their customers.
TI provides all the necessary schematics and PCB artwork to reproduce their power supplies and code modules to get applications working quickly.
The memory stick contains two programs firstly a PC based application to operate the Multi-DC Unit and installer for an application called controlSUITE. This application is essentially a centralised portal into TI's "control" product world and contains links to datasheets, manuals applications and alike.
The PC application worked exactly how the documentation stipulated.
This application works with the preinstalled demonstration firmware in the Multi DC.
Basically Multi-DC is configured to respond to requests a serial interface (which is encapsulated within USB) and DMX.
(DMX is a industry standard for Lighting and Effects control.)
LEDS turn off and on and dim up and down according to the control panel.
Checkboxes can be checked or dechecked to select various options. (I found a minor bug with one of these options)
The Multi-DC baseboard contains three identical Boost PWM power supplies to power strings of RGB LEDS (or anything else for that matter) and a SEPIC power supply to drive a string of white LEDS (or anything else for that matter). It is obvious from looking at the PCB board that the same template is used for the PWM power supplies. (I think it's TI's method of practising what they preach - Rapid prototype development).
The SEPIC power supply unit uses much larger components and is provided to demonstate a power supply that can accept a variable voltage input where the input voltage can be above or below the target voltage.
The brains for these power supplies is the F28027 and it controls these power supplies simulataneously.
It drives the MOSFET transistors using its PWM channels changing its duty cycle as necessary according to the feedback received through its ADC pins.
Both voltage and current are monitored.
Voltage is fed back from each LED strings through a voltage divider to produce a useable voltage range for the ADC.
Similarly current is fed back from each LED string through 0.1 ohm current sense resistor and OPA2350 opamp (which converts the sensed current to a voltage - transimpedance amplifier).
These readings are the appropriately rescaled and made visible by the demonstration GUI software.
The CCSv4 software was downloaded from the internet and installed on my PC. Its installation went smoothly.
I'm just about to write my own software but more on that later.
The CCS software is used to program MSP430 microcontrollers.
Rather than risk breaking the Multi-DC by wiping out the demonstration program, I obtained an MSP430 Launchpad and successfully wrote and compiled my first program.
This worked immediately so I am feeling more confident about attempting a new program for the F28027 (used by the Multi-DC).
That cat looks grumpy.
Thanks for the comments.
I got the Launchpad to "avoid going to a place where you don't want to be!" by becoming familiar with the IDE and debugger before attempting to reprogram the Multi-DC/DC and breaking it. Both have virtually identical development paths.
The Multi-DC/DC has a USB to JTAG connection to the F28027 controlDIMM however the Multi-DC/DC board but as you've found out it does not provide direct access to the I/O pins for external experimentation. The I/O pins are connected to the PWM power supplies and other items on the Multi-DC/DC board.
The only real experiments that can be done without resorting to modding the Multi-DC/DC is to;
Other experiments can be performed by either soldering extra wires to the Multi-DC/DC or removing ControlSTICK and plugging it into something else. If you don't want to create your own PCB. TI has several controlSTICK Experimenter's kits specifically designed for this purpose.
Be aware that the most controlSTICKS (including the one on the Multi-DC/DC) don't have an onboard USB JTAG interface. You could use the USB JTAG interface on the Multi-DC/DC as it has an additional connector specifically designed for this purpost.
(BTW- The controlStick with the Motor Control Kit has an onboard USB JTAG interface)
An idea of what could be done with a few mods is to obtain a more highly featured controlSTICK with more I/O and provide an Ethernet or Wireless Interface.
Nice Review! Thank you.
If you got the MSP430 Launchpad what are you using this Evalkit for?
I'm also a reviewer for this Kit but I'm not sure what to Programm with it ... no imputs / outputs etc.
Best regards, Stefan
if you are looking for good and not expensive regulated LED supply, AP8802 from Diodes is a good choice (up to 1A output current, analog and PWM dimming, few external components: choke coil, resistor, Schottky diode and capacitor, switching at 100's of kHz so flicker should not be an issue). Add some good HB LEDs from Cree or Osram and you will have good adjustable light source.
TI have the schematics, PCB artwork and code freely available. As for the selection of the type of switching power supply type Boost or SEPIC the answer is the true engineer's answer. "It depends!"
Theoretically the BOOST power supply has better current regulation but this board demonstrates that SEPIC can also be used. I haven't pulled apart the code but since the output appears flicker free and the software is Current oriented, the SEPIC power supply is adjusted from actual current readings rather than the traditional voltage feedback.
I appreciate the additional information. I am looking at an adjustable light source for some macro photography, which is why I was interested in the flicker issue. I sounds like they have done a good job of keeping the current surgest under control and each light channel seperately powered with minimum cross effect.
The Stereo output sounds like they might have originally considered either using sound to modulate the LEDs or sending sound out using the different modulation of the LEDs.