IC-TW11 Datasheet, PDF (17/25 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 17/25
recent) sample. The GAIN register value is returned in
the lower byte of the response packet.
GAIN Register
Bit
Name
7:5
-
4:0
gain
Description
Not used (0)
Hall array gain
Table 21: GAIN Register
Addr. 0x23
The Hall array gain is returned as a positive integer
in the range 0-17 (0x00-0x11). GAIN.gain = 0 is the
lowest gain and GAIN.gain = 17 is the highest gain.
Each LSB change in GAIN.gain represents a change
of approximately 1.5 dB in the Hall array gain.
Normally (i.e. in default mode; CONFIG.noagc = 0),
the GAIN register is updated automatically by the AGC
and it is not necessary to access it. The GAIN register
should only be written if the AGC is disabled (CON-
FIG.noagc = 1). When writing to the GAIN register, it is
recommended to suppress the next sample by setting
sup = 1 in the command packet to avoid sampling with
improper Hall array gain.
READING REGISTERS
A single register read requires two SPI transactions.
The first transaction sends the read command packet
containing the register address, and the second trans-
action reads the response packet containing the re-
quested data. If the next command is sent while read-
ing the response packet from the first command, only
one additional SPI transaction is required for the next
register read.
For example, the two SPI transactions to read the AN-
GLE register are shown below.
xSS
SCLK
SI
SO
supN=N0:NStartNnewNsampleNandNconversion
onNrisingNedgeNofNxSS.
00000000
DataNwignored.
wr=0:NRead
AddressN=N0: ANGLENRegister
ResponseNtoNPreviousNCommand
t _wait
ResponseNdataNlatchedNon
fallingNedgeNofNxSS
NextNCommand
b e Gain
Angle
Figure 6: Reading the ANGLE register
The host initiates reading the ANGLE register by ac-
tivating slave select (xSS) and sending a command
packet with the suppress (sup) and write (wr) bits reset,
followed by the ANGLE register address (0x00). The
data byte in the command packet is ignored but must
be provided to fill out the 16-bit packet.^∗
CONFIG.lpwr
0
(Default)
1
Suppress
bit (s)
0
1
0
1
typ.
225 µs
40 µs
t_wait
max.
300 µs
5 µs
54 µs
5 µs
Table 22: Wait Time for Reading Registers
After sending the command packet, the host deacti-
vates xSS to start the sample and conversion process.
The host must then wait for the iC-TW11 to sample the
Hall array and convert the angle before reading the re-
sponse packet. The actual wait time, t_wait, depends on
the configuration and the suppress bit in the command
packet, as shown in Table 22.
After waiting the appropriate amount of time, the host
again activates xSS and reads the response packet
while sending the next command packet.
Note that the wait times shown are valid when reading
any register, not just the ANGLE register. In speed criti-
cal applications it is recommended to set the suppress
∗ _{Note that when the ignored data byte is 0x00, the complete read ANGLE register command packet is 16 zeros. Thus, in simple applications}
using the default configuration where it is only necessary to read the angle, SI can be permanently tied low, further simplifying the SPI
interface with the host.