Refined code

ADXL435 I2C -
I2C code for use with with ADXL345 Accelerometer. Was found to not be
fast enough to meet requirements.

ADXL345_INT_DIRECT_TO_SD -
Using SPI, bypass writing ints to a string before writing to the SD
Memory. This saw a minor speed increase.

ADXL_345__NO_WRITE
reading from the ADXL345 without writing to the SD card. This
demonstrates the 23ksps data rate and can be used for debugging

ADXL_PROGMEM
Using the Arduino program space (flash memory) as opposed to the normal
SRAM to store variables. This saw a minor speed increase.

ADXL_345_SPI
REMOVED. This has become redundant.

ADXL_345_SPI_SD
basic SPI read from ADXL, concatenate data to string and write to SD
card. Also includes the issue of opening the SD file multiple times in
one loop, causing delays.

ADXL345_WRITE_IN_LOOP
refined SPI code with the SD write within the acquisition loop. The open
and close SD file commands are outside of the loop.

ADXL345_W_INT_ARRAYS
attempt to use integer arrays to increase size of acquisition loop
before SD Write operation. It was found that overall this did not
increase or decrease data acquisition rate.