TPIC8101

KNOCK SENSOR INTERFACE

SLIS110 − APRIL 2003

13

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

Table 2. Default SPI Mode

NO.

CODE

COMMAND (t)

DATA

RESPONSE (t)

1

010 D[4:0]

Set the prescaler and SDO status

OSCIN frequency

D[4:1]=0000=> 4 MHz

D[4:1]=0001=> 5 MHz

D[4:1]=0010=> 6 MHz

D[4:1]=0011=> 8 MHz

D[4:1]=0100=> 10 MHz

D[4:1]=0101=> 12 MHz

D[4:1]=0110=> 16 MHz

D[4:1]=0111=> 20 MHz

D[4:1]=1000=> 24 MHz

D[0]=0 => SDO active

D[1]=1=> SDO high impedance

SDI

(010 D[4:0] )

2

1110 000 D[0]

Select the channel

D[0]=0 => Channel 1 selected

D[1]=1=> Channel 2 selected

SDI

(1110 000 D[0])

3

00 D[5:0]

Set the band-pass center frequency

D[5:0] (see Table 1)

SDI

(00 D[5:0])

4

10 D[5:0]

Set the gain

D[5:0] (see Table 1)

SDI

(10 D[5:0])

5

110 D[4:0]

Set the integration time constant

D[4:0] (see Table 1)

SDI

(100 D[4:0])

6

0111 0001

Set SPI configuration to the advanced mode

None

SDI

(0111 0001)

NOTE: Command #6 is to enter into the advanced mode.

advanced SPI mode

The advanced SPI mode has additional features to the default SPI mode. A control byte is written to the SDI

and shifted with the MSB first. The response byte on the SDO is shifted out with the MSB first. The response

byte corresponds to the previous command. Therefore, the SDI shifts in a control byte n and shifts out a

response command byte n−1. Each control/response pair of commands requires two full 8-bit shift cycles to

complete a transmission. The control bytes with the expected response are shown in Table 3.

In the advanced SPI mode, only a power-down condition may reset the SPI mode to the default state on the

subsequent power-up cycle.