IC-TW11 Datasheet, PDF (20/25 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
USING INTERRUPTS
Rev B1, Page 20/25
The interrupt request output can be used to notify the
host µP when a sample and conversion is complete
by connecting IRQ_OUT (pin 8) to a digital input on
the host. In this case, after sending the command
packet, the host waits for the interrupt request from
the iC-TW11 before reading the response packet. This
provides faster communication than just waiting for the
maximum wait time, t_wait.
In the default configuration, IRQ_OUT = IRQ_IN AND
conversion complete. Therefore, IRQ_IN must be ac-
tive (low) in order to generate an interrupt output when
the conversion is complete. This is typically accom-
plished by connecting IRQ_IN to ground.
The interrupt logic can be changed to OR by setting
the interrupt mode bit in the CONFIG register (CON-
FIG.imod = 1). In this case, IRQ_OUT = IRQ_IN OR
conversion complete, which is the required logic for
multiple bussed devices (see BUSSING MULTIPLE ICs
on page 22).
The complete interrupt operation of the iC-TW11 is sum-
marized in the table below.
CONFIG.imod
0 (Default)
0 (Default)
1
1
IRQ_IN
Low
High
Low
High
IRQ_OUT
High → Low on conversion complete
High
Low
High → Low on conversion complete
Table 23: Interrupt operation
In all cases IRQ_OUT is deactivated on the falling edge
of slave select, xSS.
USING THE SAMPLE INPUT
The SAMPLE input (pin 13) allows an external device to
initiate sampling and angle conversion in the iC-TW11.
In the default configuration, sampling occurs on the
falling edge of the SAMPLE input. To sample on the
rising edge of the SAMPLE input, set the sample polar-
ity bit (CONFIG.spol) by writing 0x40 to the CONFIG
register (page 15).
It is also recommended to use the interrupt request
output (IRQ_OUT) to notify the host processor that a
new sample is ready when using the SAMPLE input. In
this case, the host waits for an interrupt request from
the iC-TW11 and then sends a read ANGLE register
command to fetch the new sample.
When using the SAMPLE input, it is recommended to
disable SPI sampling completely by setting the sam-
ple mode bit (CONFIG.smod) by writing 0x20 to the
CONFIG register (page 15). SPI sampling can also
be disabled by setting the suppress bit (s) in every
command packet (page 12).
Since in the default configuration sampling occurs on
the falling edge of the SAMPLE input, connecting the
SAMPLE input to xSS simulates sampling on the falling
edge of xSS. In this case, disable SPI sampling by
setting the sample mode bit (CONFIG.smod) in the
CONFIG register (page 15).