WMS7201050M WINBOND [Winbond], WMS7201050M Datasheet - Page 17

• Manufacturer Part Number: WMS7201050M
• Description: 256-TAP QUAD-CHANNEL NON-VOLATILE DIGITAL POTENTIOMETER
• Manufacturer: WINBOND [Winbond]

Inst.
No.
4
2
1
The contents of the tap register for any channel or any NVMEM location can be read back through the
SDO pin. When a command is sent, the data is clocked out on the falling edge of the clock. Since
daisy-chain operation requires data from one command to be clocked out when the next command
arrives, any read command must be followed by another command to get the correct data on the SDO
pin.
To read the contents of either the tap register or a NVMEM location, the following sequence must be
followed.
1. Send the desired read command (#2 or #4) to select the register to read
2. Send another command such as NOP and read the SDO pin on the falling edge of the clock.
Command
Name:
Read
NVMEM
Read Tap
Register
NOP to
Read
Register
7.8.5 Reading Tap Registers and NVMEM Locations
The other command could be any command, but to make sure that the chip does not change
anything, send either another Read command or a NOP command (#1).
Command Byte
1 0 1 0 A3 A2 A1 A0
1 1 0 0 x x A1 A0
0 0 0 0 x x x x
TABLE 9 – READING THE TAP REGISTERS
Data Byte 1
x x x x x x x x
x x x x x x x x
x x x x x x x D8
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Publication Release Date: January 2003
Data Byte 2
D7 D6 D5 D4 D3 D2 D1 D0
x x x x x x x x
x x x x x x x x
WMS7204
Revision 1.0
Comment
Read the
value of the
selected
NVMEM
location
Read the
value of the
selected
tap register
Output data
to SDO pin