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1  Using Arduino / Project Guidance / Re: Operating arduino at voltage less than 3.3V ? on: September 19, 2014, 09:10:56 am
The ATmega328p will operate at 8 MHz down to 2.4V so if you are running at 8 MHz you can run it on 2.8V.

If you are running at 16 MHz you should use at least 3.78V.
2  Topics / Home Automation and Networked Objects / Re: Ir Controller Using Arduino on: September 18, 2014, 09:34:20 pm
BUT if i remove some irsends say up to case 108, the program starts working again!!

That is often an indication of running out of SRAM.  If you have any constant data, particularly arrays and strig constants, you should move them into FLASH memory.  See:
3  Using Arduino / General Electronics / Re: 'Reading' PWM duty cycle on: September 18, 2014, 09:29:18 pm
unsigned long highTime pulseIn(inputPin, HIGH);
unsigned long lowTime pulseIn(inputPin, LOW);
unsigned long cycleTime = highTime + lowTime;
float dutyCycle = (float)highTime / float(cycleTime);
You may have to put in special cases for the timeouts you will get when the duty cycle is 0% or 100%.
4  Using Arduino / Installation & Troubleshooting / Re: pins_arduino.h missing when compiling with a makefile on: September 18, 2014, 09:21:47 pm
pins_arduino.h is found in the selected "variants" folder/directory like hardware/arduino/variants/standard/pins_arduino.h.  .  Perhaps that is something you can define in your makefile:
variant = standard
5  Using Arduino / Sensors / Re: GPS doubts on: September 18, 2014, 09:14:40 pm
If you are lucky the GPS uses a TTLSerial-to-USB chip for the USB interface.  Then you might be able to tap into those serial connections.  The alternative would be something like a USB Host Shield but I don't know if anyone has written the drivers to allow an Arduino to connect to a USB Serial chip.
6  Using Arduino / Project Guidance / Re: Transformers on: September 18, 2014, 06:22:35 pm
You should be able to build a transformer to get from 24VAC to 15000VAC.  If you need either of those to be DC you will need additional components.  Of course the output current will be less then 1/625th of the input current.  Do you know how much current you need to get out of the power supply?
7  Topics / Device Hacking / Re: do you recognize this asynch serial protocol? Saleae capture on: September 18, 2014, 06:18:25 pm
Not much of a sample but the shortest pulse seems to be about 0.333 mS.   If that pulse represents one bit time it would be about 3000 bits per second.  That's not very close to the common async speeds 2400 and 4800.  Perhaps it uses one of the automotive standards like CAN.
8  Using Arduino / Project Guidance / Re: Logger shield on: September 18, 2014, 06:12:42 pm
Have you looked at the built-in example File->Examples->SD->Datalogger?
9  Using Arduino / Networking, Protocols, and Devices / Re: SPI communication to the ADXRS450 gyroscope on: September 18, 2014, 04:32:18 pm
How hard can it be? It's 'just' SPI.

There's bit order, byte order, mode, and various parity bits to get right.  That may take a very close reading of the datasheet.
10  Using Arduino / Programming Questions / Re: Arduino Uno ATMEGA 16U2 CODE? on: September 18, 2014, 06:17:48 am
Yes, it is used for USB to Serial conversion.  The firmware is in your Arduino IDE distribution:

11  Community / Products and Services / Re: New product - Watchdog Timer Module for Arduino on: September 18, 2014, 06:12:43 am
FYI: The ATmega processor has a built-in watchdog timer.
12  Using Arduino / Networking, Protocols, and Devices / Re: SPI communication to the ADXRS450 gyroscope on: September 18, 2014, 05:58:10 am
Thanks for your reply. I removed the lines and had no succes. The output is -1 now, that's it.

I was wrong. I just looked at the datasheet again and your previous code was right.  As you send out Command-N you receive the results from the previous command (N-1).  The command and response are two different transactions.

It might be time to give up on the ADXRS450 and get a easier to use gyroscope. smiley-sad
13  Topics / Robotics / Re: Connecting Servo to the Arduino (branded) Robot on: September 18, 2014, 05:37:01 am
You should be able to use any of the following designations:
19 == A1 == TKD0
20 == A2 == TKD1
21 == A3 == TKD2
22 == A4 == TKD3

Each of those four locations on the board have three holes.  I assume one hole is Ground (Servo Black), one is Vcc (Servo Red), and one is Signal (Servo White or Yellow).  I don't think you need to use pinMode() on those pins if you use them with the Servo library .attach() but it couldn't hurt to try it.
14  Using Arduino / Project Guidance / Re: Battery Paradigm for a project that must last a week on: September 17, 2014, 09:18:18 pm
A 9V alkaline battery has about 500 mAh capacity at 50 mA so we can guerss that your circuit was drawing an average of about 50 mA for the ten hours the battery lasted.  To supply 50 mA for 30 days you'd need 36,000 mAh of battery capacity.

A 6V alkaline lantern battery has about 13,000 mAh of capacity so to get 30 days of life you'd need three in parallel.
15  Using Arduino / Networking, Protocols, and Devices / Re: SPI communication to the ADXRS450 gyroscope on: September 17, 2014, 09:00:18 pm
void loop() {
  digitalWrite(7, LOW);
  // Sending 4 bytes as a command

                         digitalWrite(7, HIGH);  // End of command
                         digitalWrite(7, LOW);   // Start of data retrieval
  result = SPI.transfer(0x00);
  result = result << 8 | SPI.transfer(0x00);
  result = result << 8 | SPI.transfer(0x00);
  result = result << 8 | SPI.transfer(0x00);
  digitalWrite(7, HIGH);

I'm sorry I failed to mention it before but it would be highly unusual for the Slave Select pin (7) to be set HIGH between the sending of the command and the receiving of the data.  Try removing the three indented lines.
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