ISL22426 Datasheet, PDF (13/15 Pages) Intersil Corporation – Low Noise, Low Power, SPI Bus, 128 Taps

ISL22426
Applications Information
Communicating with ISL22426
Communication with ISL22426 proceeds using SPI interface
through the ACR (address 1000b), IVRi (addresses 0000b,
0001b) and WRi (addresses 0000b, 0001b) registers.
The wiper of the potentiometer is controlled by the WRi
register. Writes and reads can be made directly to these
registers to control and monitor the wiper position without
any non-volatile memory changes. This is done by setting
MSB bit at address 1000b to 1.
The non-volatile IVRi stores the power up value of the wiper.
IVRs are accessible when MSB bit at address 1000b is set
to 0. Writing a new value to the IVRi register will set a new
power-up position for the wiper. Also, writing to this register
will load the same value into the corresponding WRi as the
IVRi. Reading from the IVRi will not change the WRi, if its
contents are different.
Examples
A. Writing to the IVR
This sequence will write a new value (77h) to the IVR0
(non-volatile):
Set the ACR (Addr 1000b) for NV write (40h)
Send the ID byte, Instruction Byte, then the Data byte
010100001100100001000000
(Sent to DI)
B. Reading from the WR
This sequence will read the value from the WR1 (volatile):
Write to ACR first to access the WRs
Send the ID byte, Instruction Byte, then the Data byte
010100001100100011000000
(Sent to DI)
Read the data from WR1 (Addr 0001b)
Send the ID byte, Instruction Byte, then Read the Data byte
0101000010110001xxxxxxxx
(Out on DO)
Set the IVR0 (Addr 0000b) to 77h
Send the ID byte, Instruction Byte, then the Data byte
010100001100000001110111
(Sent to DI)
13
FN6180.2
September 8, 2009