IC-TW11 Datasheet, PDF (18/25 Pages) IC-Haus GmbH – 10-BIT ULTRA LOW POWER MAGNETIC ABSOLUTE ROTARY ENCODER

iC-TW11 10-BIT ULTRA LOW POWER^preliminary
MAGNETIC ABSOLUTE ROTARY ENCODER
Rev B1, Page 18/25
bit in the command packet whenever possible to take
advantage of the reduced wait time.
Alternatively, the host can wait for the iC-TW11 to acti-
vate its interrupt request output (IRQ_OUT) before read-
ing the response packet. See USING INTERRUPTS
on Page 20 for more information.
The sine and cosine of the sampled angle can be read
from the SIN and COS registers respectively. This is
useful, for example, for calculating sin² + cos² in the
host as a more accurate measure of magnetic field
strength or for implementing automatic gain control in
the host.
Reading the sine and cosine values takes three SPI
transactions. First, the host sends a SIN register read
command packet with or without the suppress bit set.
After waiting the appropriate amount of time, the host
reads the sine value from the response packet while
simultaneously writing the COS register read command
packet with the suppress bit set to ensure simultane-
ously-sampled values. After waiting the appropriate
amount of time, the host reads the cosine value from
the response packet while writing the next command.
Likewise, the raw sampled Hall effect sensor signals
can be read from the HALL0, HALL120, and HALL240
registers respectively. This data can be analyzed in the
host for quality and integrity to provide general system
health status.
Reading the Hall register values takes four SPI trans-
actions. First, the host sends a HALL0 register read
command packet with or without the suppress bit set.
After waiting the appropriate amount of time, the host
reads the 0° Hall sensor value from the response packet
while simultaneously writing a HALL120 register read
command packet with the suppress bit set to ensure
simultaneously-sampled values. After waiting the ap-
propriate amount of time, the host reads the 120° Hall
sensor value from the response packet while simultane-
ously writing a HALL240 register read command packet
with the suppress bit set to ensure simultaneously-sam-
pled values. After waiting the appropriate amount of
time, the host reads the 240° Hall sensor value from
the response packet while writing the next command.
The chip identification, configuration, status, and Hall
sensor gain may be read from the DEVICE, CONFIG,
STATUS, and GAIN registers respectively. Reading
each of these registers requires two SPI transactions,
similar to reading the ANGLE register as explained
previously.
WRITING REGISTERS
The chip configuration and the Hall array gain of the
iC-TW11 can be changed by writing to the CONFIG or
GAIN registers respectively. A register write requires a
single SPI transaction.
For example, the SPI transaction to write to the CON-
FIG register is shown below.
51µs
xSS
Data1is1written1on1rising1edge1of1xSS.
SCLK
SI
SO
11100001
Data
sup1=11:1Suppress1new1sample.
wr=1:1Write
Address1=10x21:1CONFIG1Register
Response1to1Previous1Command
Next1Command
Undefined1Response
Figure 7: Writing the CONFIG register
The host initiates writing to the CONFIG register by
activating slave select (xSS) and sending a command
packet with the suppress (sup) and write (wr) bits set,
followed by the CONFIG register address (0x21) and
the required data. The host then deactivates xSS and
the data is written to the CONFIG register. The host
should then wait 5 µs before sending the next command.
Note that the response packet returned while sending
the next command is undefined and should be ignored
by the host.
It is only necessary to write to the CONFIG register if the
default configuration of the iC-TW11 must be changed.
The default configuration is: