IC-TW11 Datasheet, PDF (23/25 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
CHAINING MULTIPLE ICs
Rev B1, Page 23/25
Multiple iC-TW11 slaves can also be chained together
using a single SPI host. In this case, all devices are
accessed together as a group and all data is read back
together by the host in an extended response packet.
In a chained configuration, SCLK and xSS on all de-
vices are connected together while SI and SO, and
IRQ_IN and IRQ_OUT are linked from one device to
the next, as shown in Figure 10.
iC-TW11 3
xSS
SCLK
SO
SI
IRQ_ IRQ_
IN OUT
iC-TW11 2
xSS
SCLK
SO
SI
IRQ_ IRQ_
IN OUT
iC-TW11 1
xSS
SCLK
SO
SI
IRQ_ IRQ_
IN OUT
Host µP
xCS
SCLK
MO
IRQ
MI
Figure 10: Chained connection of multiple iC-TW11s
In operation, the host initiates a sample of all of the
iC-TW11s by activating the chip select output (xCS)
and sending three consecutive read register commands
by clocking 3 x 16 = 48 bits through the SI/SO chain.
As long as the xSS input of the iC-TW11s is held low,
data is shifted through the chained devices from SI
to SO. After all commands have been loaded to the
chained devices, the host deactivates xSS to execute
the commands simultaneously. This extended packet
communication structure is shown below.
xSS
16 bits
16 bits
16 bits
t_wait
16 bits
16 bits
16 bits
SI Command 3 Command 2 Command 1
Command 3 Command 2 Command 1
SO Response 3 Response 2 Response 1
Response 3 Response 2 Response 1
Extended Response Packet
to Previous Extended Command Packet
Extended Response Packet
to Extended Command Packet
Figure 11: Extended communication packet structure with chained iC-TW11s
The host then either waits the appropriate amount of
time (see Page 17) or waits for the interrupt request
(IRQ) to be received to read the sampled angles as 48
consecutive bits over the SI/SO chain. In this case, the
default interrupt logic of AND is used so that the host
receives an interrupt request only when all the iC-TW11
slaves have completed sampling and conversion. See
USING INTERRUPTS on Page 20 for more information.