|
|
楼主 |
发表于 2014-5-13 17:17:15
|
显示全部楼层
官方提供初始化的配置
void MMA8451_Initial(void)
{
uint8 n, int_mask;
uint8 CurrentReadMode;
uint8 CurrentRange;
uint8 CurrentDemo;
CurrentReadMode = READ_MODE_14BITS;
CurrentRange = Full_Scale_Range_2g;
CurrentDemo = DEMO_TAP;
/* Put MMA845xQ into Standby Mode */
MMA8451_Standby();
/* Configure sensor for:
Sleep Mode Poll Rate of 1.56Hz (640ms) for maximum power saving
System Output Data Rate (ODR) of 200Hz (5ms)
read mode 14-bit data
*/
// n = ASLP_RATE_640MS + DATA_RATE_5MS;
n = ASLP_RATE_20MS + DATA_RATE_5MS;
if (CurrentReadMode == READ_MODE_8BITS)
n |= FREAD_MASK;
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, CTRL_REG1, n);
/* Select user-specified sensitivity, 2g/4g/8g */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, XYZ_DATA_CFG_REG, CurrentRange);
/* Configure Sleep/Wake modes
SMODS1:0 : 1 1 Low power mode when asleep
SLPE : 1 Sleep enabled
MODS1:0 : 0 0 Normal mode when awake
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, CTRL_REG2, 0x1c);
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, ASLP_COUNT_REG, 15); /* Sleep after 10 seconds of inactivity */
/* Disable the FIFO */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, F_SETUP_REG, 0x00);
switch (CurrentDemo)
{
case DEMO_TRANSIENT:
case DEMO_SHAKE:
case DEMO_ORIENTATION:
/* In all three of these demo modes we configure the accelerometer to detect
movement:
DEMO_TRANSIENT - We configure the accelerometer to detect small movements
of > 0.063g
DEMO_SHAKE - We configure the accelerometer to detect movements
of > 0.5g
DEMO_ORIENTATION - We don't care about the movement data itself, but
we use transient detection so that the accelerometer
can tell us when the board isn't being used. When
it transitions to Sleep mode, we can put the main
processor to sleep too.
By using the high-pass filter we can remove the constant effect of gravity,
and only detect changes in acceleration. See Application Note AN4071.
*/
/* ELE = 1 : Event latch enabled
ZTEFE = 1 : Raise event on any of Z, Y, X axes
YTEFE = 1
XTEFE = 1
HBF_BYP = 0 : High-pass filter enabled
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, TRANSIENT_CFG_REG, 0x1e);
/* Set High-pass filter cut-off frequency for best sensitivity */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, HP_FILTER_CUTOFF_REG, 0x03);
if (CurrentDemo == DEMO_SHAKE)
{
/* Transient is indicated when acceleration on one of the axes
is above threshold 8 x 0.063g = 0.5g
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, TRANSIENT_THS_REG, 8);
}
else
{
/* Transient is indicated when acceleration on one of the axes
is above threshold 1 x 0.063g - i.e. a small movement
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, TRANSIENT_THS_REG, 1);
}
/* Internal debounce counter. For an ODR of 200Hz in Normal mode,
motion is indicated after 5 x 1 = 5ms.
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, TRANSIENT_COUNT_REG, 1);
/* Interrupt signalled on INT1 when transient detected */
int_mask = INT_EN_TRANS_MASK;
if (CurrentDemo == DEMO_ORIENTATION)
{
/* Interrupt also signalled when new data is ready */
int_mask |= INT_EN_DRDY_MASK;
/* Set up TPMs to produce edge-aligned PWM signals */
//configure_LEDs_for_PWM ();
}
break;
case DEMO_TAP:
/* Configure the accelerometer to detect single and double taps...
(See Application Note AN4072)
*/
/* Z configured for Single Tap and Double Tap with Latch enabled */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, PULSE_CFG_REG, 0x70);
/* Enable low-pass filter */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, HP_FILTER_CUTOFF_REG, PULSE_LPF_EN_MASK);
/* Set Z Threshold to 16 x 0.063g = 1.0g
Note: In a more sophisticated application we could dynamically
track the orientation and configure X, Y Z with changing thresholds
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, PULSE_THSZ_REG, 16);
/* Set the Pulse Time Limit for 30 ms at 200 Hz ODR in Normal Mode with the LPF Enabled
30 ms/5 ms = 6 counts
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, PULSE_TMLT_REG, 6);
/* Set the Pulse Latency Timer to 100 ms, 200 Hz ODR Normal Mode, LPF Enabled
80 ms/10 ms = 8 counts
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, PULSE_LTCY_REG, 8);
/* Set the Pulse window to 400 ms, 200 Hz Normal Mode, LPF Enabled
300 ms/10 ms = 30 counts
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, PULSE_WIND_REG, 30);
/* Interrupt signalled on INT1 when pulse detected */
int_mask = INT_EN_PULSE_MASK;
break;
case DEMO_FREEFALL:
/* Configure accelerometer for linear freefall detection...
[Note that the accelerometer can also detect tumbling, as
described in Application Note AN4070]
*/
/* ELE = 1 : Event latch enabled
OAE = 0 : Detect Freefall
ZEFE = 1 : Raise event on any of Z, Y, X axes
YEFE = 1
XEFE = 1
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, FF_MT_CFG_1_REG, 0xb8);
/* Freefall is indicated when acceleration on all three axes
falls below threshold 3 x 0.063g = 0.19g
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, FT_MT_THS_1_REG, 3);
/* Internal debounce counter. For an ODR of 200Hz in Normal mode,
freefall is indicated after 5 x 20 = 100ms of falling - a drop
of a few centimetres - See Application Note AN4070
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, FF_MT_COUNT_1_REG, 20);
/* Interrupt signalled on INT1 when Freefall detected */
int_mask = INT_EN_FF_MT_1_MASK;
break;
}
/* Configure interrupts */
int_mask |= INT_EN_ASLP_MASK; /* Also generate interrupt on
Sleep <--> Wake transition
*/
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, CTRL_REG4, int_mask);
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, CTRL_REG5, 0xfd); /* All interrupts mapped to MMA_INT1 */
MMA8451WriteRegister(MMA8451_I2C_ADDRESS, CTRL_REG3, 0x78); /* Active-low interrupts, all functions
wake system
*/
/* Throw away any stale interrupt info */
// last_int_source_reg = 0;
/* Put MMA845xQ into Active Mode */
MMA8451_Active();
/* Enable MMA_INTx interrupts */
// KBI1_SC_KBIE = 1;
}
但是也未产生中断信号 |
|
发表于 2014-5-13 17:10:51
