23
votes
Accepted
How to access multiple SPI interfaces on Arduino
Assuming you just want to connect two SPI slave devices to the SPI bus and use them in a mutually exclusive way under software control, with the Arduino as the master, then you just need to make sure ...
- 590
12
votes
Accepted
How to increase SD card write speed in arduino
OK. So, I tried the SDFat lib. This library is definitely better than the default SD library that comes with adruino.
But that is not how I solved my problem of low data-rate.
I followed the ...
- 435
10
votes
Use LED on pin 13 again after using the SD library
It is possible to use the LED on pin 13 again by disabling the SPI bus that is used by the SD library to read/write data to/from the SD card. To disable the SPI bus, simply call SPI.end() after ...
- 151
10
votes
How to use a microSD card reader with SCK instead of CLK?
SCK stands for SPI ClocK
CLK stands for SPI CLocK
Two different acronyms for the same thing.
- 104k
8
votes
What do these pins mean? Where should I plug them in?
This is called the SPI interface (See Serial Peripheral Interface, Wikipedia. The pin names typically used for SPI are:
GND : Power Ground
VCC : Power input
CS : Chipselect
SCK/SCLK (SD-Clock): SPI ...
- 12.7k
6
votes
Accepted
How can I do web hosting having all the code of the site stored in a sd?
You wrote:
the site does not have to be static but constantly updated with new
temperature data.
A good option is to use Ajax.
The basic idea is to split the site in two parts:
a static part, ...
- 39.2k
5
votes
Accepted
Serial.write and Serial.println return different values? Cannot use correct ones
The text file contains the sequential ascii values that spell out the data, not binary data. println in printing the numerical value of each byte. For example, the 10's println prints are '\n' ...
- 4,360
5
votes
Accepted
How to pass a filename to a function? What type of variable is the filename?
String literals are of type const char *. Ordinary char *s can be passed to it though; the const means that the compiler will make sure that the function doesn't attempt to change the contents.
void ...
- 17.6k
5
votes
Accepted
SD card fails to initialize
The first thing to try is to use the 'proper' pins for the SPI:
SCK to Pin 10 on Arduino ---> Pin 13
CS to Pin 11 on Arduino ---> Pin 10
MISO to Pin 12 on Arduino ---> Pin 12
MOSI to Pin 13 ...
- 78
5
votes
Accepted
What is the best way to get more RAM for a sound buffer?
A simple SPI SRAM chip. Available up to 128KB, such as the 23LC1024: http://www.microchip.com/wwwproducts/en/23LC1024
- 104k
5
votes
Accepted
Need help with 2X3 matrix for braille
First of all, may I say "Thank you" for helping your friend like that? I cannot think of a better way to use an Arduino than as a driver for a Braille display like you describe!
As you know, Braille ...
5
votes
Accepted
Writing "theremin" outputs to a MIDI file on an SD card
The short answer would be "yes, it is possible". There are lots of gadgets around that record MIDI. They would have microprocessors in them, and they would have something like an SD card, ...
- 35.7k
5
votes
Accepted
Reading bytes from a file on SD Card - Understanding Buffer
You don't have to, it's just one way of doing it.
Basically the read function needs a pointer to a buffer to store the data in. By using an array with one entry you get a pointer to a buffer that is ...
- 104k
4
votes
Accepted
Signal sampling: losing data every 103 points when it is recorded in SD
It's all to do with writing to the SD card.
You have a buffer of 512 bytes which is one "block" of the SD card. When you have written to the card enough to fill that buffer up it has to write that ...
- 104k
4
votes
One free pin. Need to display output for the user?
Seems you have I²C on the board you could possibly use an I²C LCD backpack, like from breakouts if you already have an LCD, this means you can have the RTC and display on the I²C bus and probably more ...
- 1,437
4
votes
How to increase SD card write speed in arduino
Many factors would decide if you can reach this wanted speed. Only some of these.
1. Your Software
The SdFat Library is faster than the standard SD Library of the Arduino IDE. It also has an easy to ...
- 495
4
votes
How to increase SD card write speed in arduino
Avoid the handshake getting a buffer!
Use
SD.write(buf,size);
Hi every one, I'm working in a project with the same issue. I was following the same steps of yours and got exactly the same numbers. I'...
- 41
4
votes
Need help with 2X3 matrix for braille
Each character will be 6 bits (so let's use a byte to store it) and we'll use the following bit to LED mapping
bit0 bit1
bit2 bit3
bit4 bit5
Now you just need an array of bytes where each byte ...
- 393
4
votes
Accepted
Understanding why should avoid “String” and alternative solutions
First, let me point out a problem in your code, completely unrelated to
your question:
AcX = Wire.read()<<8|Wire.read();
The C++ standard does not specify in which order the two reads will be
...
- 39.2k
4
votes
Understanding why should avoid “String” and alternative solutions
Edgar answers your first question about String and printing very nicely. Majenko also has a nice description here of the pitfalls.
Regarding your second question about GPS/efficiency/speed:
use ...
- 2,009
4
votes
Using a Micro SD card for data logging, bad idea? Reliable?
We've been maintaining a network of loggers (60+ currently deployed) using SD card connected directly to the SPI pins (see: http://www.mdpi.com/1424-8220/18/2/530 for details) and our experience is ...
- 101
4
votes
Arduino SD Card open file modes append / overwrite
The Arduino SD library is an Arduino wrapper of old version of SdFat library (put into utility subfolder of the SD library). This SdFat library has constants like O_READ, O_WRITE, O_APPEND.
Arduino ...
- 17k
4
votes
Arduino SD Card open file modes append / overwrite
You only need to open the file with FILE_WRITE and use file.seek(EOF) to go to de end of the file. After that you can write whatever you want that will be appended to the end of the file.
File ...
4
votes
Writing to sd card with a sampling rate 50ms or less? I have a sketch that writes to sd every 1s but jams at faster sampling rates. Please help?
Some tips:
Do not open the open and close the file in every loop sequence (I think you can use the flush command to save/update the file.
Do not save strings, but save the raw data and pulse string. ...
- 12.7k
4
votes
What do these pins mean? Where should I plug them in?
CS = Chip select
DI = Data In (MOSI)
VCC
SCK = Serial Clock
GND
DO = Data Out (MISO)
CD (not sure what it stands for, but this pin isn't used when connecting to an Arduino. I think it's used for ...
- 11.2k
3
votes
What is the difference between file.print() and file.write()
The File class inherits from the Stream class, which in turn inherits from the Print class.
The Serial class inherits from the Stream class, which in turn inherits from the Print class.
print() and ...
- 104k
3
votes
Accepted
SD.begin() fails second time
I know this question is relatively old but still, if you wnat to run SD.begin(chipselect); again first call if(root.isOpen()) root.close(); I added this to the library. This way SD.begin(chipselect) ...
- 46
3
votes
Record video with CMOS camera using Arduino
Arduinos have two major drawbacks:
Not enough memory.
Way too slow.
There's a shield to help you do that:
http://nootropicdesign.com/ve/
http://blog.arduino.cc/2011/03/24/arduino-computer-vision-...
- 1,551
3
votes
using seek() in Arduino to go to the end of a variable-sized file
You can only seek to an absolute position from the start of the file. Fortunately there is the size() method that can tell you where the end is, though.
file.seek(file.size());
- 104k
3
votes
Using TMRpcm library, the audio does not play
This is now 5 months later - but I recently had the same problem.
Because the TMRpcm library plays through pulse width modulation, make sure your speakers are hooked up to a PWM capable pin.
That ...
- 31
Only top scored, non community-wiki answers of a minimum length are eligible