C communication, Nd 4.3 – PNI SpacePoint Scout User Manual
Page 10
PNI Sensor Corporation
Doc #1017545 r03
SpacePoint Scout User Manual
– January 2013
Page 10 of 19
Note: The CRC mentioned in this document adheres to a 16-bit Fletcher algorithm. See
kResetRef
Cursor position tracking is relative to a reference established by the user. Normally a
user will point the SpacePoint Scout at the center of a screen, then press a keyboard
button or a button on the user‟s device that resets the cursor to the center of the
screen. The UART command to set the cursor at the center of the screen is 0x34.
4.3 I
2
C Communication
The SpacePoint Scout also supports communication with the host system via an I
2
C interface.
The module acts as the Slave device and the user‟s processor acts as the Master device. The
slave address (HwADDR) is 0x18. All data is presented as unsigned integers in big Endian
format. (For UART communication the format is different, being little Endian.) Command
sequences are given below for polling data and resetting the cursor reference frame.
Polling Quaternion Data
Master ST HwADDR
0x31
SR HwADDR+1
MAK
Slave
SAK
SAK
SAK QX MSB
Master
MAK
MAK
MAK
MAK
Slave
QX LSB
QY MSB
QY LSB
QZ MSB
QZ LSB
Master MAK
MAK
NMAK SP
Slave
QW MSB
QW LSB
Polling Cursor Position (Hpos and Vpos) Data
Master
ST HwADDR
0x33
SR HwADDR+1
MAK
Slave
SAK
SAK
SAK Reserved
Master
MAK
MAK
MAK
MAK
Slave
Reserved
Reserved
Reserved
Reserved
Master
MAK
MAK
MAK
MAK
Slave
Reserved
Reserved
Reserved
Reserved
Master
MAK
MAK
MAK
MAK