SX8645I05AWLTRT Semtech, SX8645I05AWLTRT Datasheet - Page 73

• Manufacturer Part Number: SX8645I05AWLTRT
• Description: 12-ch Capacitive Touch Solution (Button & Wheel)
• Manufacturer: Semtech

ADVANCED COMMUNICATIONS & SENSING
6.7 NVM burn
The content of the SPM can be copied permanently (burned) into the NVM to be used as the new default
parameters. The burning of the NVM can be done up to three times and must be done only when the SPM is
completely written with the desired data. The NVM burn must be done in Active or Doze mode.
Once the NVM burn process is terminated IrqSrc[6] will be set and INTB asserted.
After a reset the burned NVM parameters will be copied into the SPM.
The number of times the NVM has been burned can be monitored by reading NvmCount from the I2C register
SpmStat[2:0].
Figure 56 shows the simplified diagram of the NVM counter. The SX8645 is delivered with empty NVM and
NvmCount set to zero. The SPM points to the QSM.
Each NVM burn will increase the NvmCount. At the fourth NVM burn the SX8645 switches definitely to the QSM.
The burning of the SPM into the NVM is done by executing a special sequence of four I2C commands.
This is illustrated in Figure 57.
Revision 7_5, February 10
1. Write the data 0x62 to the I2C register I2CKeyMsb.
2. Write the data 0x9D to the I2C register I2CKeyLsb.
3. Write the data 0xA5 to the I2C register I2CSpmBaseAddr.
4. Write the data 0x5A to the I2C register I2CSpmBaseAddr.
1)
2)
3)
4)
S
SA
A
P
S
S
S
S
Figure 56
SA
SA
SA
SA
: Start condition
: Slave address
: Slave acknowledge
: Stop condition
Figure 57: NVM burn procedure
Touch Controller (12 sensors) with Enhanced LED Drivers
© 2010 Semtech Corp.
0
0
0
0
Simplified Diagram NvmCount
A
A
A
A
0xAC
0xAD
0x0E
0x0E
73
Ultra Low Power, Capacitive Button and Wheel
A
A
A
A
0x9D
0xA5
0x5A
0x62
Terminate the I2C write by a STOP.
Terminate the I2C write by a STOP.
Terminate the I2C write by a STOP.
Terminate the I2C write by a STOP.
A
A
A
A
P
P
P
P
From master to slave
From slave to master
DATASHEET
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SX8645