wms7202 Winbond Electronics Corp America, wms7202 Datasheet - Page 8

• Manufacturer Part Number: wms7202
• Description: 256-tap Dual-channel Non-volatile Digital
• Manufacturer: Winbond Electronics Corp America

Each channel has four NVMEM positions available for storing the output buffer operating mode and
the potentiometer setting. These NVMEM positions can be directly written through the SPI using a
write command (#5) with address and data bytes. Another command (#7) is available that stores the
current output buffer operating mode and potentiometer settings into the selected NVMEM position.
Bit A3 and A2 in the instruction byte decide which NVMEM position is used. (See Table 5)
All potentiometers are loaded with the value stored in the NVMEM position 0 for their respective
channel on power up.
Write-protect ( WP ) disables any changes of current content in the NVMEM regardless of the
commands, except that NVMEM setting can be retrieved using commands 4, 6 of Table
Write-Protect ( WP ) pin provides hardware NVMEM protection feature with WP tied to Vss. WP ,
which is active at logic LOW, should be tied directly to V
Reading and writing to NVMEM requires an internal access cycle to complete before the next
command can be sent. The following commands have additional flow control using the R/B pin.
Read Tap Register (#2)
Read NVMEM (#4)
Program NVMEM (#5)
Load Tap Register(#6)
Program NVMEM with Tap Register (#7)
The R/B bit will be pulled HIGH when CS goes LOW, and will stay HIGH indicating the chip is ready
to accept another command. After sending one of those commands, the R/B pin should be polled to
determine when the device is ready to accept the additional data.
This flow control can be used on all commands without any performance penalty although it is only
needed on the commands listed above.
7.3. N
7.4 F
7.3.1 Write Protect of NVMEM
LOW
ON
-V
C
OLATILE
ONTROL
M
EMORY
(NVMEM)
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DD
if it is not being used.
WMS7202
5.
Therefore,