Hallo an alle, hab mal eine Frage zu einem IMU Combiboard (http://www.sparkfun.com/datasheets/Sensors/IMU/6DOF-Digital-v10.pdf) Will den Sensor über TWI/I2C mit einem ATMega32 aus lesen und auf einem Breedboard eine kleine Schaltung mit LEDs erstellen die dann zur Auswertung dient ( z.B. GrüneLED Pos.-Auslenkung in x/y/z, RoteLED Neg.-Auslenkung ...), um mich dann später einwenig in Regler (P, PD, PDI) einzuarbeiten. Der IMU hat ein integriertes I2C Interface wenn ich die Datenblätter der beiden Sensoren (Gyro/LinAcc) richtig interpretiert habe. Allerdings haben sich bei mir nach dem Lesen diverser TWI und GCC TWI Tutorials einige Fragen aufgetan. Der IMU hat 6 Anschlüsse GND, 3,3V, SCL, SDA sind für die TWI Komunikation, allerdings hat er noch einen INT0 und einen INT1 PORT. Dienen diese Anschlüssen zur getrennten Ansprechung der Sensoren? Es müssen ja 6 Werte (je 3) ausgelesen werden. Habe ja hier noch eine Beispiel Programm für'n ATMega128 gfunden: -------------------------------------------------------------------- /* TWI Interface Library for an ATMega168 written by Ryan Owens 9/28/10 */ #include <util/twi.h> void twiInit(unsigned long scl_freq) { //Set the TWI Prescaler to 1 //(Actually this is default setting...) //Set up the TWI Bit Rate TWBR = F_CPU/(2*(long)scl_freq)-8; //(SCL_FREQ = F_CPU/(16+2*TWBR) *According to datasheet } //Puts the ATmega in Master Transmitter mode and sends a value to a register //pre: sla - i2c address of slave // reg_addr - the register to address // value - the value to write in the register location //returns: 1-Success // TWSR - Failure (The TWI failure code) char twiTransmit(char sla, char reg_addr, char value) { //Send the start condition TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN); //Clear int bit(by writing a 1), enable twi and send start while (!(TWCR & (1<<TWINT))); //Wait for the interrupte bit to get set if(TW_STATUS != TW_START)return TWSR; //No matter what we start with a write to the slave TWDR = sla | TW_WRITE; //Put the slave address in the twi data register TWCR = (1<<TWINT)|(1<<TWEN); //Send the address to the slave while (!(TWCR & (1<<TWINT))); //Wait for the operatation to complete if (TW_STATUS != TW_MT_SLA_ACK)return TWSR; //Make sure we received an ack from the slave. //Load the register into the slave device that we want to alter TWDR = reg_addr; TWCR = (1<<TWINT)|(1<<TWEN); //Send the register address through the twi interface while (!(TWCR & (1<<TWINT))); //Wait for operation to complete if (TW_STATUS != TW_MT_DATA_ACK)return TWSR; //Make sure we received an ack from the slave //Now send the actual register data to the slave TWDR = value; TWCR = (1<<TWINT)|(1<<TWEN); //Send the register value through the twi interface while (!(TWCR & (1<<TWINT))); //Wait for operation to complete if (TW_STATUS != TW_MT_DATA_ACK)return TWSR; //Make sure we received an ack from the slave //We're finished. Send a stop. TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO); return 1; } //Reads a value from a specified register //pre: sla - i2c address of slave // reg_addr - The address of the register to read from // value - a pointer to a character //post: value is assigned the value read from the register //returns: 1 - Success // TWSR - Failur char twiReceive(char sla, char reg_addr, char * value) { //Send the start condition TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN); //Clear int bit(by writing a 1), enable twi and send start while (!(TWCR & (1<<TWINT))); //Wait for the interrupte bit to get set if (TW_STATUS != TW_START)return TWSR; //Check the TWI status, return if bad status. //Start Condition has been transmitted //Send SLA+W to TWDR TWDR = sla|TW_WRITE; //Put the slave address in the twi data register TWCR = (1<<TWINT)|(1<<TWEN); //Send the address to the slave while (!(TWCR & (1<<TWINT))); //Wait for the operatation to complete if(TW_STATUS != TW_MT_SLA_ACK)return TWSR; //SLA+W has been transmitted, Ack has been received //Load the register into the slave device that we want to read TWDR = reg_addr; TWCR = (1<<TWINT)|(1<<TWEN); //Send the register address through the twi interface while (!(TWCR & (1<<TWINT))); //Wait for operation to complete if(TW_STATUS != TW_MT_DATA_ACK)return TWSR; //Data byte has been transmitted, Ack has been received //Now send a 'repeated start' to switch to master receiver mode TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN); //Clear int bit(by writing a 1), enable twi and send start while (!(TWCR & (1<<TWINT))); //Wait for the interrupte bit to get set if (TW_STATUS != TW_REP_START)return TWSR; //A Repeated Start condition has been received //Send the SLA+R TWDR = sla | TW_READ; //Load the slave address and the read bit into the data register TWCR = (1<<TWINT)|(1<<TWEN); //Send the address+R to the slave while(!(TWCR & (1<<TWINT))); //Wait for the operation to complete if (TW_STATUS != TW_MR_SLA_ACK)return TWSR; //Make sure we got the right ack. //SLA+R has been transmitted, Ack has been received //Get the value from the pre-configured register on the slave TWCR = (1<<TWINT)|(1<<TWEN); //Tell the slave to send the next value and send NACK afterwards while(!(TWCR & (1<<TWINT))); //Wait for the operation to complete if (TW_STATUS != TW_MR_DATA_NACK)return 5; //Make sure we got the right ack. //Data byte has been received, Nack has been returned //Send a stop TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO); *value = TWDR; return 1; //Return the value we got from the register } //Resets the TWI interface void twiReset(void) { TWCR = 0; } -------------------------------------------------------------- Werd daraus nur leider nich wirklich schlau. Vllt kann mir jemand helfen der sich damit auch schon einmal herum geärgert hat. Grüße Ben
Angehängte Dateien:
-
10121-02b.jpg
(4,7 KB)
-
10121-03b.jpg
(4,7 KB)
