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view src/i2c.asm @ 0:11d4fc797f74
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author | heinrichsweikamp |
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date | Wed, 24 Apr 2013 19:22:45 +0200 |
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children | 4e3f133dfbf4 |
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;============================================================================= ; ; File i2c.asm ; ; I2C Interface to HMC5883L and MMA8452Q ; ; HMC5883L's read address (8-Bit): 0x3D ; HMC5883L's write address (8-Bit): 0x3C ; ; MMA8452Q's read address (8-Bit): 0x39 ; MMA8452Q's write address (8-Bit): 0x38 ; ; Copyright (c) 2012, JD Gascuel, HeinrichsWeikamp, all right reserved. ;============================================================================= ; HISTORY ; 2012-08-22 : [mH] Creation #include "ostc3.inc" ; Mandatory header #include "wait.inc" i2c CODE WaitMSSP: decfsz i2c_temp,F ; check for timeout during I2C action bra WaitMSSP2 bra I2CFail ; timeout occured WaitMSSP2: btfss PIR1,SSPIF bra WaitMSSP clrf i2c_temp bcf PIR1,SSPIF nop return I2C_WaitforACK: btfss SSPCON2,ACKSTAT ; checks for ACK bit from slave return I2CFail: rcall I2CReset ; I2C Reset bcf PIR1,SSPIF clrf i2c_temp return I2CReset: ; Something went wrong (Slave holds SDA low?) clrf SSP1CON1 ; wake-up slave and reset entire module clrf SSP1CON2 clrf SSP1STAT bcf TRISC,3 ; SCL OUTPUT bsf TRISC,4 ; SDA Input bcf PORTC,3 movlw d'9' movwf i2c_temp ; clock-out 9 clock cycles manually I2CReset_1: bsf PORTC,3 ; SCL=1 nop nop nop nop btfsc PORTC,4 ; SDA=1? bra I2CReset_2 ; =1, SDA has been released from slave bcf PORTC,3 ; SCL=0 nop nop bcf PORTC,3 nop nop decfsz i2c_temp,F bra I2CReset_1 ; check for nine clock cycles I2CReset_2: bsf TRISC,3 ; SCL Input clrf SSP1CON1 ; setup I²C Mode WAITMS d'10' ; Reset-Timeout for I2C devices movlw b'00000000' ; with slew rate control movwf SSPSTAT movlw b'00101000' movwf SSP1CON1 movlw b'00000000' movwf SSP1CON2 movlw 0x27 movwf SSP1ADD return I2C_TX: movwf SSP1BUF rcall WaitMSSP bra I2C_WaitforACK ; Returns... I2C_TwoBytesRX_div16: ; Get two bytes and devide lo:hi/16 (signed) rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,hi ; Data Byte rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,lo ; Data Byte I2C_TwoBytesRX_div16_2: ; devide lo:hi/16 (signed) only bcf STATUS,C btfsc hi,7 ; Copy sign bit to carry bsf STATUS,C rrcf hi ; /2 rrcf lo bcf STATUS,C btfsc hi,7 ; Copy sign bit to carry bsf STATUS,C rrcf hi ; /4 rrcf lo bcf STATUS,C btfsc hi,7 ; Copy sign bit to carry bsf STATUS,C rrcf hi ; /8 rrcf lo bcf STATUS,C btfsc hi,7 ; Copy sign bit to carry bsf STATUS,C rrcf hi ; /16 rrcf lo return global I2C_RX_accelerometer I2C_RX_accelerometer: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x38 ; address rcall I2C_TX movlw 0x01 rcall I2C_TX bsf SSP1CON2,RSEN ; Repeated start condition (!) rcall WaitMSSP movlw 0x39 ; address rcall I2C_TX ; Chip orientation on the PCB requires ; Original = Corrected ; x = -x ; y = -y ; z = -z rcall I2C_TwoBytesRX_div16 ; Get two bytes and devide /16 (signed) comf hi ; 16bit sign change. negf lo btfsc STATUS,C ; Carry to propagate ? incf hi,F ; YES: do it. movff lo,accel_DX+0 movff hi,accel_DX+1 ; Copy result rcall I2C_TwoBytesRX_div16 ; Get two bytes and devide /16 (signed) comf hi ; 16bit sign change. negf lo btfsc STATUS,C ; Carry to propagate ? incf hi,F ; YES: do it. movff lo,accel_DY+0 movff hi,accel_DY+1 ; Copy result rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,hi ; Data Byte bsf SSP1CON2, RCEN ; Enable recieve mode rcall WaitMSSP ; According to datasheet there should be no Master Acknowlegde for the last Byte (accel_DZ+0)... movff SSP1BUF,lo ; Data Byte rcall I2C_TwoBytesRX_div16_2; devide lo:hi/16 (signed) only comf hi ; 16bit sign change. negf lo btfsc STATUS,C ; Carry to propagate ? incf hi,F ; YES: do it. movff lo,accel_DZ+0 movff hi,accel_DZ+1 ; Copy result bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP return I2C_OneByteRX: bsf SSP1CON2, RCEN ; Enable recieve mode rcall WaitMSSP bsf SSP1CON2,ACKEN ; Master acknowlegde rcall WaitMSSP return global I2C_RX_compass I2C_RX_compass: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x3C ; address rcall I2C_TX movlw 0x03 rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bcf PIR1,SSPIF bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x3D ; address rcall I2C_TX ; Compass IC sends data in following order: ; x MSB ; x LSB ; z MSB ; z LSB ; y MSB ; y LSB ; Chip orientation on the PCB requires ; Original = Corrected ; x = -y ; z = z ; y = x rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,compass_DY+1; Data Byte rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,compass_DY+0; Data Byte banksel compass_DY comf compass_DY+1 ; 16bit sign change. negf compass_DY+0 btfsc STATUS,C ; Carry to propagate ? incf compass_DY+1,F ; YES: do it. banksel common rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,compass_DZ+1; Data Byte rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,compass_DZ+0; Data Byte rcall I2C_OneByteRX ; Get one byte movff SSP1BUF,compass_DX+1; Data Byte bsf SSP1CON2, RCEN ; Enable recieve mode rcall WaitMSSP movff SSP1BUF,compass_DX+0; Data Byte bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP return global I2C_init_compass I2C_init_compass: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x3C ; address rcall I2C_TX movlw 0x00 rcall I2C_TX ; movlw b'01101001' ; ConfigA: 3Hz, 8 Samples averaged, Test Mode (Positive Bias) movlw b'01101000' ; ConfigA: 3Hz, 8 Samples averaged ; movlw b'00111000' ; ConfigA: 75Hz, 2 Samples averaged rcall I2C_TX movlw b'00100000' ; ConfigB, 1090Gauss Gain ; movlw b'10000000' ; ConfigB, 440Gauss Gain rcall I2C_TX movlw b'00000000' ; Continous Mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bsf compass_enabled return global I2C_init_compass_fast I2C_init_compass_fast: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x3C ; address rcall I2C_TX movlw 0x00 rcall I2C_TX movlw b'00111000' ; ConfigA: 75Hz, 2 Samples averaged rcall I2C_TX movlw b'00100000' ; ConfigB, 1090Gauss Gain rcall I2C_TX movlw b'00000000' ; Continous Mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bsf compass_enabled return global I2C_sleep_compass I2C_sleep_compass: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x3C ; address rcall I2C_TX movlw 0x00 rcall I2C_TX movlw b'01101000' ; ConfigA rcall I2C_TX movlw b'00100000' ; ConfigB rcall I2C_TX movlw b'00000010' ; Idle Mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bcf compass_enabled return global I2C_init_accelerometer I2C_init_accelerometer: rcall I2C_sleep_accelerometer ; Regs can only be changed in St.By mode bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x38 ; address rcall I2C_TX movlw 0x0E ; XYZ_DATA_CFG rcall I2C_TX movlw b'00000000' ; High pass Filter=0 , +/- 2g range rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x38 ; address rcall I2C_TX movlw 0x2A ; CTRL_REG1 rcall I2C_TX ; movlw b'00110000' ; CTRL_REG1: 160ms data rate, St.By Mode movlw b'00110100' ; CTRL_REG1: 160ms data rate, St.By Mode, reduced noise mode rcall I2C_TX movlw b'00000010' ; CTRL_REG2: High Res in Active mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x38 ; address rcall I2C_TX movlw 0x2A ; CTRL_REG1 rcall I2C_TX ; movlw b'00110001' ; CTRL_REG1: 160ms data rate, Active Mode movlw b'00110101' ; CTRL_REG1: 160ms data rate, St.By Mode, reduced noise mode, Active Mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP return global I2C_sleep_accelerometer I2C_sleep_accelerometer: bsf SSP1CON2,SEN ; Start condition rcall WaitMSSP movlw 0x38 ; address rcall I2C_TX movlw 0x2A ; CTRL_REG1 rcall I2C_TX movlw b'00000000' ; St. By Mode rcall I2C_TX bsf SSP1CON2,PEN ; Stop condition rcall WaitMSSP return END