sx8649 Semtech Corporation, sx8649 Datasheet - Page 74

• Manufacturer Part Number: sx8649
• Description: Ultra Low Power, Capacitive Button And Wheel Touch Controller 8 Sensors With Enhanced Led Drivers
• Manufacturer: Semtech Corporation

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 59 shows the simplified diagram of the NVM counter. The SX8649 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 SX8649 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 60.
Revision 7_6, 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 59
SA
SA
SA
SA
: Start condition
: Slave address
: Slave acknowledge
: Stop condition
Figure 60: NVM burn procedure
© 2010 Semtech Corp.
Touch Controller (8 sensors) with Enhanced LED Drivers
0
0
0
0
Simplified Diagram NvmCount
A
A
A
A
0xAC
0xAD
0x0E
0x0E
74
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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SX8649