Webinar Video
Q&A
Q: What do you think about a separate Power-Supply-Board instead of integrated Power-Supply in each Board?
I did consider this as a possibility, but felt that the real benefit of the T-Board was that it was simple and self-contained. I felt that the added complexity of a separate power supply board would not result in any cost-savings, and would just make the board a little less easy to use.
Q: How much current can the T-board provide the external circuitry?
The T-Boards can provide 1A: the voltage regulators are rated at 1A, and the PTC Fuse trip current is at 1A. If you're running higher loads like motors, it's probably good practice to run these off a separate power source to reduce noise.
Q: What's the current consumption for these? Can they be operated from a battery?
One of the key reasons for the design layout of the T-Boards was to optimise current consumption. The December 2014 edition of Elektor will contain an article explaining how to reduce your consumption by 99% (compared to an Arduino Uno) - at this level I estimate up to 6 years on an 800mAh battery (ignoring normal internal battery discharge).
Q: What's the operating voltage?
The T-Boards allow you to choose either 5V or 3.3V using a voltage selection jumper. Voltage supply should be a minimum of 6V through the power jack.
Q: Arduino has 40mA current per pin does this system match that?
Yes, the 40mA limit is what the ATmega328 can handle - as the T-Board 28 uses this microcontroller the current limits are the same. Note though that the 40mA is an "absolute maximum"; 20mA is the accepted norm at 5V. From the ATmega328 datasheet note that there are overall limits to the controller:
Although each I/O port can source more than the test conditions (20mA at VCC = 5V, 10mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed:
ATmega48A/PA/88A/PA/168A/PA/328/P:
- The sum of all IOH, for ports C0 - C5, D0- D4, ADC7, RESET should not exceed 150mA.
- The sum of all IOH, for ports B0 - B5, D5 - D7, ADC6, XTAL1, XTAL2 should not exceed 150mA.
Q: Is the code portable to other Atmel AVR's, like code in the Arduino IDE works on different arduino board with different AVR chips?
One of the great things the Arduino IDE does is hide the hardware complexities. If you prefer to work like this, then you can still use the Arduino IDE with the T-Boards - however you will need to add support to the Arduino IDE for the T-Board 14 and T-Board 8 (refer to http://highlowtech.org/?p=1695). If you use Atmel Studio, then the bulk of your code will port to other AVR chips - however you'll need to manually review the register settings and of course ensure all the peripherals are supported in the various AVR chips (eg. the ATmega328 has a Serial UART, but the ATtiny's don't). The benefit of working with registers directly is the increased flexibility - but it does come at a cost of some increased complexity.
Q: I like the low power footprint of T-Board, and amd the project I want to use T-Board will be on IoT projects so what are thecapabilities of T-Board on IoT, as IoT (Internet of Things) is the place where Power is very precious?
Absolutely! You're in the right place as the T-Board was designed with this in mind. Keep your eyes open for the December issue of Elektor for a full run-down of how to reduce power consumption.
Q: Hi Andrew, What made you select Atmel processors, instead of say PIC microcontrollers?
A good question! The short answer is that I began my journey into embedded systems with an Arduino UNO - so the Atmel processors were a natural progression. One of the goals of the T-Board was to make it easy for hobbyists to make the transition away from the Arduino environment to working directly with the raw microcontroller - so Atmel was an easier path for that. I've used the T-Board to launch myself into working with other manufacturer's microconctrollers, and hope that they allow others to do this as well.
Q: I missed it, but what was the average current on the presented project?
I did not measure the current of the demo project, as it wasn't optimised for low-current usage - it was designed for a more easy-to-follow demo of the board. The project I worked on for the Dec issue of Elektor had consumption down to an average of 1uA in sleep and approximately 65uA when taking an ADC reading.
Q: Can you change the clock speed?
Yes you can. For the T-Board 14 and T-Board 8 I would typically use the internal oscillator (given the limited number of I/O pins) - so you would need to set the fuses to control the speed. The T-Board 28 is well-suited to using different external crystals - I have used a range from 16MHz down to 32.767kHz watch crystals, as well as the internal oscillator. One of the benefits of altering the clock speed is of course power savings.