I have an ADXL355 accelerometer attached to an Adafruit Feather Adalogger. I can configure and read the sensor. I can also write binary values to the SD card. The problem occurs when I try to read from the sensor and then write that data to the SD card. The only thing I can think of is I'm somehow messing up the SPI communication but I can't see where. I looked through pins_arduino.h
for my board and the SD Card (pin 4) is on a different register than pin 10 so I don't see how I'm breaking things.
My operations proceed like this. Global sensor creation, Serial.begin
, SD.begin
, SPI.begin
, Test sensor connection, Create file for output on SD card, Initialize sensor, Read sensor FIFO, Write to file, repeat last 2 forever.
The file is created but remains at 0 file size, ie nothing is actually written to the card.
The sensor can operate at 4 kHz which was hard to achieve using the digitalWrite
functions so I switched to using the port registers on the Feather. I do it like this:
#include <SM_ADXL355_SPI_fast.h>
#include <SPI.h>
#include <SD.h>
#define cardSelect 4
ADXL355_SPIF adxl355(&DDRB, &PORTB, _BV(6)); // values taken from pins_arduino.h, tested and working on pin 10
void setup() {
Serial.begin(57600);
while(!Serial){
// wait for Serial
}
SD.begin(cardSelect);
SPI.begin();
while(!adxl355.TestConnection()){
delay(1000);
}
adxl355.OpenFile("TestSPI.bin");
adxl355.Initialize(1, 10, 0); // set range to 2g's, frequency to 4 Hz and filter to off
}
void loop() {
while(true){ // avoid Arduino overhead of their loop function
adxl355.ReadFIFO();
adxl355.WriteFIFOToFile();
}
}
Here is the ADXL constructor
ADXL355_SPIF::ADXL355_SPIF(volatile uint8_t * outReg, volatile uint8_t * outPort, uint8_t bitValue) : sensorOutReg(outReg), sensorPort(outPort), sensorBitValue(bitValue){
*sensorOutReg |= sensorBitValue;
*sensorPort |= sensorBitValue;
sensorWriteCount = 0;
}
TestConnection
tests that the DeviceID reads 0xAD
. Initialize
sets the G range, sample rate in Hz and filter. I have tested these with serial output and they work properly.
OpenFile
looks like this:
bool ADXL355_SPIF::OpenFile(const String& fileName){
sensorFile = SD.open(fileName, FILE_WRITE);
if (!sensorFile){
Serial.print("Could not create file: ");
Serial.println(fileName);
return false;
}
return true;
}
After running this a file does get created on the SD card called "TESTSPI.BIN" with 0 file size.
ReadFIFO
reads the numbers of entries in FIFO, stored as fifoCount
and then populates a buffer (sensorFIFO[32][3]
) with the values from the FIFO. I've printed this buffer to Serial to show that it's working. Here is that function
void ADXL355_SPIF::ReadFIFO(){
ReadRegister(ADXL355_RA_FIFO_ENTRIES, 1);
fifoCount = buffer[0];
ReadFIFOInternal();
return;
}
void ADXL355_SPIF::ReadFIFOInternal(){
SPI.beginTransaction(SPISettings(10000000, MSBFIRST, SPI_MODE0));
*sensorPort &= ~sensorBitValue;
uint8_t spiCommand = ADXL355_RA_FIFO_DATA << 1 | ADXL355_READ;
SPI.transfer(spiCommand);
int i = 0;
unsigned long tempV;
unsigned long value;
while(i < fifoCount){
for (int ptr = 0; ptr < 3; ++ptr){
buffer[0] = SPI.transfer(0x0);
value = buffer[0];
value <<= 12;
tempV = SPI.transfer(0x0);
tempV <<= 4;
value |= tempV;
tempV = SPI.transfer(0x0);
tempV >>=4;
value |= tempV;
if (buffer[0] & 0x80) {
value |= 0xFFF00000;
}
long lValue = static_cast<long>(value);
sensorFIFO[i][ptr] = scaleFactor * lValue;
}
i += 3;
}
SPI.endTransaction();
*sensorPort |= sensorBitValue;
return;
}
Here is WriteFIFOToFile
:
void ADXL355_SPIF::WriteFIFOToFile(){
if (fifoCount > 0){
sensorFile.write(reinterpret_cast<const char *>(&sensorFIFO), 4 * fifoCount);
}
sensorWriteCount += fifoCount;
if (sensorWriteCount >= 100){
sensorFile.flush();
sensorWriteCount = 0;
}
}
After allowing this to run for a while the file size is always 0. I tried a simple binary write function just to test the card. It looks like this and it worked.
#include <SD.h>
#define cardSelectPin 4
const float pi=3.14159;
File oFile;
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
while(!Serial){
// wait for serial
}
SD.begin(cardSelectPin);
oFile = SD.open("Test.bin", FILE_WRITE);
Serial.println(sizeof(int));
Serial.println(sizeof(float));
float testFloat[32][3];
for (int i = 0; i < 32; ++i){
for (int j = 0; j < 3; ++j){
testFloat[i][j] = pi * (i + 1) + j;
}
}
oFile.write(reinterpret_cast<const char *>(&testFloat), sizeof(float) * 96);
oFile.close();
Serial.println("Finished writing file.");
}
void loop() {
// put your main code here, to run repeatedly:
}