NVS Example

This example shows the use of the NVS component to save a variable to the NVS and load it after reset.

How to use example

The example outputs a log that counts up the number of times the system has been reset since the NVS was last cleared.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(Replace PORT with the name of the serial port to use.)

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

NVS Example Output

NVSHandle Example Output

First run:

Opening Non-Volatile Storage (NVS) handle... Done
Reading restart counter from NVS ... [NVSHandle/E][0.061]: The value is not initialized in NVS, key = 'restart_counter'
The value is not initialized yet!
Updating restart counter in NVS ... Done
Committing updates in NVS ... Done

Restarting in 10 seconds...
Restarting in 9 seconds...
Restarting in 8 seconds...
Restarting in 7 seconds...
Restarting in 6 seconds...
Restarting in 5 seconds...
Restarting in 4 seconds...
Restarting in 3 seconds...
Restarting in 2 seconds...
Restarting in 1 seconds...
Restarting in 0 seconds...
Restarting now.

Subsequent runs:

Opening Non-Volatile Storage (NVS) handle... Done
Reading restart counter from NVS ... Done
Restart counter = 1
Updating restart counter in NVS ... Done
Committing updates in NVS ... Done

Restarting in 10 seconds...
Restarting in 9 seconds...
Restarting in 8 seconds...
Restarting in 7 seconds...
Restarting in 6 seconds...
Restarting in 5 seconds...
Restarting in 4 seconds...
Restarting in 3 seconds...
Restarting in 2 seconds...
Restarting in 1 seconds...
Restarting in 0 seconds...
Restarting now.

Restart counter will increment on each run.

To reset the counter, erase the contents of flash memory using idf.py erase-flash, then upload the program again as described above.