Sensors

Freescale Semiconductor

11

MMA7455L

THRESHOLD DETECTION FOR MOTION AND FREEFALL CONDITIONS

CASE 1: Motion Detection

Integer Value: X >Threshold OR Y >Threshold OR Z > Threshold

Reg $18 THOPT=1; Reg 19 LDPL=0, Set Threshold to 3g, which is 47 counts (16 counts/g). Set register $1A LDTH = $2F.

CASE 2: Motion Detection

Absolute: ||X|| > Threshold OR ||Y|| >Threshold OR ||Z|| > Threshold

Reg $18 THOPT=0; Reg 19 LDPL=0, Set Threshold to 3g, which is 47 counts (16 counts/g). Set register $1A LDTH = $2F.

CASE 3: Freefall Detection

Integer Value: X < Threshold AND Y < Threshold AND Z <Threshold

Reg $18 THOPT=1; Reg 19 LDPL=1, Set Threshold to 0.5g, which is 7 counts (16 counts/g). Set register $1A LDTH = $07

CASE 4: Freefall Detection

Absolute: ||X|| <Threshold AND ||Y|| < Threshold AND ||Z||< Threshold

Reg $18 THOPT=0; Reg 19 LDPL=1, Set Threshold to +/-0.5g, which is 7 counts (16 counts/g). Set register $1A LDTH = $07.

TH = $2F

TH = $2F

TH = $D1

TH = $07

TH = $07

TH = $F9