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421  Using Arduino / General Electronics / Re: [SOLVED] Reset for a 3.3V breakout board connected to an Uno on: July 20, 2013, 08:05:34 pm
I did some research and 2 ways stood out as being 'quick and dirty' but workable. Simplifying factors for me are that the signal (RESET) hardly changes at all and it is only one way from 5V to 3V. The easiest ways:
- Voltage divider as already previously mentioned
- Zener diode voltage clamp on the signal

Here are some references in case anyone is interested

http://jamesreubenknowles.com/level-shifting-stragety-experments-1741

http://www.daycounter.com/Circuits/Level-Translators/Level-Translators.phtml
http://webhome.csc.uvic.ca/~mcheng/466/spring.2010/handouts/references/level-translation-techniques.pdf
http://codeandlife.com/2012/04/06/level-shifting-101/
422  Using Arduino / General Electronics / Re: Reset for a 3.3V breakout board connected to an Uno on: July 20, 2013, 08:32:24 am
Here's the breakout boards https://www.sparkfun.com/products/9943

It is mounted on a UNO prototyping shield and the I/O pins are tied to start it up in MIDI mode.
423  Using Arduino / General Electronics / [SOLVED] Reset for a 3.3V breakout board connected to an Uno on: July 20, 2013, 03:29:44 am
I have breakout board for a component that is to the Uno using the serial port only. I need to reset the breakout board when the Uno is reset, but the mismatch in voltage levels (3.3V vs 5V) means that I can't connect the Uno reset signal directly to the breakout board.

Any suggestions for would be the easiest (cheapest and least components) way of doing this, given that there is just one signal whose level needs to be shifted?
424  Using Arduino / Displays / Re: Where to get 16X2 displays with pins both on top and bottom, cheap? on: July 19, 2013, 04:29:06 pm
Have you looked on eBay?
425  Using Arduino / LEDs and Multiplexing / Re: 60 Second countdown using a 2 digit Seven second display on: July 14, 2013, 04:51:05 am
I have some code on my repository (link below) for a countdown timer that may be useful for you.
426  Using Arduino / Programming Questions / Re: Question about hex codes on: July 12, 2013, 06:04:41 pm
The numbers you have listed are all 16 bit integers. The number you showed separately (0x02FD48B7) is a long value (32 bits).

Each hex digit takes 4 bits (0-F), so it is easy to work out the data types you need to store the values. Up to 2 hex digits fits in a uint8_t, up to 4 in a uint16_t and up to 8 in a uint32_t.
427  Using Arduino / Programming Questions / Re: Pointers / Data types (LCD4884) on: July 04, 2013, 09:11:50 pm
A % followed by another % character will write a single % to the stream.
428  Using Arduino / Programming Questions / Re: Pointers / Data types (LCD4884) on: July 04, 2013, 08:33:51 pm
Just to add to PaulS response, if you want to have leading zeroes for single digits, use %02d. This will keep the string exactly the same length.
429  Using Arduino / Programming Questions / Re: Calling functions from another file on: July 04, 2013, 04:59:42 pm
You can include a .h or a .cpp file, that would be clearer than the .ino.

A .cpp without objects (just functions) should also work as long as you have a separate header file with function prototypes so that the file ordering doesn't get in the way. Haven't tried this, but it should work.
430  Using Arduino / Sensors / Re: Least lines for 8 switches on: July 04, 2013, 04:52:21 pm
A parallel to serial input converter like the 74HC165 is cheap, available and uses 3 lines to interface as many of these chips as you need (they cascade). Lots of examples (code and circuits) on how these are used. Each chip takes 8 bits in parallel and squirts them out as a serial stream that you can assemble into a byte at the Arduino end. Datasheet here http://www.nxp.com/documents/data_sheet/74HC_HCT165.pdf.

The reverse comms is done using the 74HC595 chip.
431  Using Arduino / Displays / Re: Why is there a pot connected to the lcd? on: July 02, 2013, 07:21:31 am
Usually it is used to adjust the contrast for the display. Different lighting conditions can mean that you can't see the LCD so adjustment may be necessary.
432  Using Arduino / Sensors / Re: Sensor for stringed instruments on: July 02, 2013, 07:19:06 am
Electric guitar pickup?

I have also seen suggested that a piezo disc can be used to detect the vibration of the string.
433  Using Arduino / Programming Questions / Re: Pointers / Data types (LCD4884) on: June 30, 2013, 10:04:14 pm
A pointer is just a memory address. In this case the memory address of the start of the string, but in general ANY memory address.

To get the address of a variable you use the '&' operator (ie, &fred gives you the address of the variable fred). For arrays, this is technically the address of the first element (&var[0]), but the convention is that a reference to an array variable name is the same as the address of that array (ie, 'var' is the same as '&var[0]'). A character string is an array of characters, so the name is the address.

In your case, declaring a variable of 14 characters in size (option 2) creates a memory space that you can use and modify as you need. Just declaring a pointer to a 'constant' string, does not allow you to modify that string, as you do not know where the string is stored. In either case you can use the name of the string (option 1 because it is a pointer, option 2 because it is the first element of the array).

Personally I would use option 2 if you need to change the string.
434  Using Arduino / Displays / Re: Character LCD: print a filled block without using custom characters on: June 27, 2013, 10:19:50 pm
One of the characters in the ROM is a filled in block. Google is your friend here, the character set is on a large number of web sites. Look for "LCD hitachi HD44780 datasheet pdf" and something should land.

Alternatively, just print every characters from 9 onwards and see which one it is. A lot of them above ASCII 127 will be Japanese.

BTW, you have to use lcd.write(255) to get the ascii character, not print().
435  Using Arduino / Displays / Re: How to display "big" numbers on a character LCD on: June 27, 2013, 05:04:27 pm
I have done soimething similar but I think my code is a bit more compact. See the link below for my repository if you are interested.
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