I have spent several nights trying to figure out how to make this work. My hardware an APM and a scp1000.
I have connected MISO line directly , and MOSI,SCK,SS lines trough a SF logic level converter rx lines.
Code was taken from the BeginningArduino book .
/*
SCP1000 Mega
DRDY N/A
CSB 53 via Logic Level Convertor
MISO 50 (straight through)
MOSI 51 via Logic Level Convertor
SCK 52 via Logic Level Convertor
3.3v 3.3v
GND GND
TRIG GND
PD GND
*/
// SPI PINS
#define SLAVESELECT 53
#define SPICLOCK 52
#define DATAOUT 51 //MOSI
#define DATAIN 50 //MISO
#define UBLB(a,b) ( ( (a) << 8) | (b) )
#define UBLB19(a,b) ( ( (a) << 16 ) | (b) )
//Addresses
#define PRESSURE 0x1F //Pressure 3 MSB
#define PRESSURE_LSB 0x20 //Pressure 16 LSB
#define TEMP 0x21 //16 bit temp
//#define INTERVAL 900 // Time interval in seconds (approx.)
int dots[124], dotCursor = 0, counter = 0;;
char rev_in_byte;
int temp_in;
float hPa;
unsigned long pressure_lsb;
unsigned long pressure_msb;
unsigned long temp_pressure;
unsigned long pressure;
void setup()
{
Serial.begin(115200);
byte clr;
pinMode(DATAOUT, OUTPUT);
pinMode(DATAIN, INPUT);
pinMode(SPICLOCK,OUTPUT);
pinMode(SLAVESELECT,OUTPUT);
digitalWrite(SLAVESELECT,HIGH); //disable device
SPCR = B01010011; // SPi Control Register
//MPIE=0, SPE=1 (on), DORD=0 (MSB first), MSTR=1 (master), CPOL=0 (clock idle when low),CPHA=0 (samples MOSI on rising edge), SPR1=1 & SPR0=1 (250kHz)
clr=SPSR;// SPi Status Register
clr=SPDR; // SPi Data Register
delay(10);
write_register(0x03,0x09); // High Speed Read Mode
write_register(0x03,0x0A); // High Resolution Measurement Mode
}
void loop()
{
delay(500);
getPressure();
//Serial.println(hPa);
temp_in = read_register16(TEMP);
float tempC = float(temp_in)/20.0;
float tempF = (tempC*1.8) + 32;
//Serial.print("t=");
//Serial.println(tempC);
}
void getPressure() {
pressure_msb = read_register(PRESSURE);
pressure_msb &= B00000111;
pressure_lsb = read_register16(PRESSURE_LSB);
pressure_lsb &= 0x0000FFFF;
pressure = UBLB19(pressure_msb, pressure_lsb);
Serial.println(pressure);
pressure /= 4;
hPa = float(pressure)/100;
}
char spi_transfer(char data)
{
SPDR = data; // Start the transmission
while (!(SPSR & (1<<SPIF))) // Wait for the end of the transmission
{
};
return SPDR; // return the received byte
}
char read_register(char register_name)
{
char in_byte;
register_name <<= 2;
digitalWrite(SLAVESELECT,LOW); //Enable SPI Device
spi_transfer(register_name); //Write byte to device
in_byte = spi_transfer(0x00); //Send nothing but get back register value
digitalWrite(SLAVESELECT,HIGH); // Disable SPI Device
delay(10);
return(in_byte); // return value
}
unsigned long read_register16(char register_name)
{
byte in_byte1;
byte in_byte2;
float in_word;
register_name <<= 2;
digitalWrite(SLAVESELECT,LOW); //Enable SPI Device
spi_transfer(register_name); //Write byte to device
in_byte1 = spi_transfer(0x00);
in_byte2 = spi_transfer(0x00);
digitalWrite(SLAVESELECT,HIGH); // Disable SPI Device
in_word = UBLB(in_byte1,in_byte2);
return(in_word); // return value
}
void write_register(char register_name, char register_value)
{
register_name <<= 2;
register_name |= B00000010; //Write command
digitalWrite(SLAVESELECT,LOW); //Select SPI device
spi_transfer(register_name); //Send register location
spi_transfer(register_value); //Send value to record into register
digitalWrite(SLAVESELECT,HIGH);
}
What I get are zeros.
Any advice appreciated)