MCP41XXX/42XXX
CS
SCK
SO
Microcontroller
CS
SCK
SI
CS
SCK
SI
SO
CS
SCK
SI
Device 1
SO
EXAMPLE:
Device 2
If you want to load the following
command/data into each part
in the chain.
Device 3*
Device 1
Device 2
XX10XX11 11001100
Device 3
XX01XX10 11110000
XX10XX00 10101010
After 16 clocks, Device 2 and
Device 3 will both have all
zeros clocked in from the
previous part’s shift register.
c
Start by setting CS low and
clocking in the command and
data that will end up in Device
3 (16 clocks).
Device 1
Device 2
XX10XX00 10101010
Device 3
00000000 00000000
00000000 00000000
After 32 clocks, Device 2 has
the data previously loaded
into Device 1 and Device 3
gets 16 more zeros.
d
Clock-In the command and
data for Device 2 (16 more
clocks). The data that was pre-
viously loaded gets shifted to
the next device on the chain.
Device 1
Device 2
XX01XX10 11110000
Device 3
XX10XX00 10101010
00000000 00000000
e
After 48 clocks, all 3 devices
have the proper command/
data loaded into their shift
registers.
Clock-In the data for Device 1
(16 more clocks). The data that
was previously loaded into
Device 1 gets shifted into
Device 2 and Device 3 contains
the first byte loaded. Raise the
CS line to execute the com-
mands for all 3 devices at the
same time.
Device 1
Device 2
XX10XX11 11001100
Device 3
XX01XX10 11110000
XX10XX00 10101010
* Last device on a daisy-chain may be a single channel MCP41XXX device.
FIGURE 5-4:
Daisy-Chain Configuration.
DS11195C-page 20
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
