I have removed the beta version of this program. Please download the newest SdFat from GitHub GitHub - greiman/SdFat: Arduino FAT16/FAT32 exFAT Library.
AnalogBinLogger is now a SdFat example https://github.com/greiman/SdFat/tree/master/SdFat/examples/AnalogBinLogger.
Also see this directory https://github.com/greiman/SdFat/tree/master/AnalogBinLoggerExtras
The tests described below were done on an Uno.
Here is part of the readme file.
AnalogBinLogger.ino logs analog data to a binary SD file at high rates.
Samples are logged at regular intervals by using timer1. Timer/Counter1
Compare Match B is used to trigger the ADC for the first pin in a sample.
The ADC is triggered for remaining sample pins in the ADC conversion complete
interrupt routine.Data is captured in the ADC interrupt routine and saved in 512 byte buffers.
Buffered data is written to the SD in a function called from loop(). The
entire data set is written to a large contiguous file as a single multi-block
write. This reduces write latency problems.Many inexpensive SD cards work well at lower rates. I used a $6.00
SanDisk 4 GB class 4 card for testing.SanDisk class 4 cards work well at fairly high rates. I used the 4 GB SanDisk
card to log a single pin at 40,000 samples per second.The bintocsv folder contains a PC program for converting binary files to
CSV files. I have included a executable for Windows. Linux and Mac users
can build from the included source files. bintocvs is a command line program.bintocsv binFile csvFile
The attached file, DATA.png, is a plot of a 2 kHz sine wave logged at 40,000 samples per second. FFT.png shows a FFT of this data.
I did a reliability test logging five analog pins at 5,000 samples per second. This is an ADC rate of 25,000 values per second. I logged 512 MB of data without dropping any values.
Serial output from the test.
Sample pins: 0 1 2 3 4
ADC bits: 10
ADC clock kHz: 500
Sample Rate: 5000.00
Sample interval usec: 200.0000
Creating new file
Erasing all data
Logging - type any character to stop
Truncating file
File renamed: ANALOG10.BIN
Max block write usec: 920
Record time sec: 10239.992
Sample count: 51199950
Samples/sec: 5000.00
Overruns: 0
Done
Here is the first part of the csv file produced from the test by the included bintocvs program.
Interval,200.0000,usec
pin0,pin1,pin2,pin3,pin4
0,1023,0,670,0
0,1023,0,670,0
0,1023,0,670,0
0,1023,0,670,0
0,1023,0,670,0
0,1023,0,670,0
Pins 0, 2, 4 are connected to ground, pin 1 to 5V and pin 3 to 3.3V.
Here is the configuration section of the logger.
//------------------------------------------------------------------------------
// Analog pin number list for a sample. Pins may be in any order and pin
// numbers can be repeated.
const uint8_t PIN_LIST[] = {0, 1, 2, 3, 4};
//------------------------------------------------------------------------------
// Sample rate in samples per second.
const float SAMPLE_RATE = 5000; // Must be 0.25 or greater.
// The interval between samples in seconds, SAMPLE_INTERVAL, can be set to a
// constant instead of being calculated from SAMPLE_RATE. SAMPLE_RATE is not
// used in the code below. For example, setting SAMPLE_INTERVAL = 2.0e-4
// will result in a 200 microsecond sample interval.
const float SAMPLE_INTERVAL = 1.0/SAMPLE_RATE;
// Setting ROUND_SAMPLE_INTERVAL non-zero will cause the sample interval to
// be rounded to a a multiple of the ADC clock period and will reduce sample
// time jitter.
#define ROUND_SAMPLE_INTERVAL 1
//------------------------------------------------------------------------------
// ADC clock rate.
// The ADC clock rate is normally calculated from the pin count and sample
// interval. The calculation attempts to use the lowest possible ADC clock
// rate.
//
// You can select an ADC clock rate by defining the symbol ADC_PRESCALER to
// one of these values. You must choose an appropriate ADC clock rate for
// your sample interval.
// #define ADC_PRESCALER 7 // F_CPU/128 125 kHz on an Uno
// #define ADC_PRESCALER 6 // F_CPU/64 250 kHz on an Uno
// #define ADC_PRESCALER 5 // F_CPU/32 500 kHz on an Uno
// #define ADC_PRESCALER 4 // F_CPU/16 1000 kHz on an Uno
// #define ADC_PRESCALER 3 // F_CPU/8 2000 kHz on an Uno (8-bit mode only)
//------------------------------------------------------------------------------
// Reference voltage. See the processor data-sheet for reference details.
// uint8_t const ADC_REF = 0; // External Reference AREF pin.
uint8_t const ADC_REF = (1 << REFS0); // Vcc Reference.
// uint8_t const ADC_REF = (1 << REFS1); // Internal 1.1 (only 644 1284P Mega)
// uint8_t const ADC_REF = (1 << REFS1) | (1 << REFS0); // Internal 1.1 or 2.56
//------------------------------------------------------------------------------
// File definitions.
//
// Maximum file size in blocks.
// The program creates a contiguous file with FILE_BLOCK_COUNT 512 byte blocks.
// This file is flash erased using special SD commands. The file will be
// truncated if logging is stopped early.
const uint32_t FILE_BLOCK_COUNT = 256000;
// log file base name. Must be six characters or less.
#define FILE_BASE_NAME "ANALOG"
// Set RECORD_EIGHT_BITS non-zero to only record the high 8-bits of the ADC.
#define RECORD_EIGHT_BITS 0
//------------------------------------------------------------------------------
// Pin definitions.
//
// Digital pin to indicate an error, set to -1 if not used.
// The led blinks for fatal errors. The led goes on solid for SD write
// overrun errors and logging continues.
const int8_t ERROR_LED_PIN = 3;
// SD chip select pin.
const uint8_t SD_CS_PIN = SS;
