Add example that uses the C type of NVS API

examples/nvs_get_set_c_style.rs

@@ -0,0 +1,78 @@
+//! Updates tags from the NVS (default partition).
+//! 
+//! Note that this module exposes two separate set of APIs:
+//! * the get_XXX/set_XXX API (where XXX is u8, str, etc.) - this is only for interop with C code that uses the C ESP IDF NVS API as well.
+//! * the `get_raw`/`set_raw` APIs that take a `&[u8]`. This is the "native" Rust API that implements the `RawStorage` trait from `embedded-svc` and it should be preferred actually, as you can layer on top of it any serde you want.
+//! 
+//! More info reagarding NVS:
+//! https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/storage/nvs_flash.html
+
+use esp_idf_sys::{self as _}; // If using the `binstart` feature of `esp-idf-sys`, always keep this module imported
+
+use esp_idf_svc::nvs::*;
+use esp_idf_svc::log::EspLogger;
+use log::info;
+
+
+fn main() -> anyhow::Result<()> {
+ EspLogger::initialize_default();
+
+ let nvs_default_partition: EspNvsPartition<NvsDefault> =
+ EspDefaultNvsPartition::take().unwrap();
+
+ let test_namespace = "test_ns";
+ let mut nvs = match EspNvs::new(nvs_default_partition, test_namespace, true) {
+ Ok(nvs) => {
+ info!("Got namespace {:?} from default partition", test_namespace);
+ nvs
+ }
+ Err(e) => panic!("Could't get namespace {:?}", e),
+ };
+
+ let tag_u8 = "test_u8";
+
+ match nvs.set_u8(tag_u8, 42) {
+ Ok(_) => info!("Tag updated"),
+ // You can find the meaning of the error codes in the output of the error branch in:
+ // https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/error-codes.html
+ Err(e) => info!("Tag not updated {:?}", e),
+ };
+
+ match nvs.get_u8(tag_u8).unwrap() {
+ Some(v) => info!("{:?} = {:?}", tag_u8, v),
+ None => info!("{:?} not found", tag_u8),
+ };
+
+ let tag_test_str = "test_str";
+ // String values are limited in the IDF to 4000 bytes, but our buffer is shorter.
+ const MAX_STR_LEN: usize = 100;
+
+ let the_str_len: usize = nvs.str_len(tag_test_str).map_or(0, |v| {
+ info!("Got stored string length of {:?}", v);
+ let vv = v.unwrap_or(0);
+ if vv >= MAX_STR_LEN {
+ info!("Too long, trimming");
+ 0
+ } else {
+ vv
+ }
+ });
+
+ match the_str_len == 0 {
+ true => info!("{:?} does not seem to exist", tag_test_str),
+ false => {
+ let mut buffer: [u8; MAX_STR_LEN] = [0; MAX_STR_LEN];
+ match nvs.get_str(tag_test_str, &mut buffer).unwrap() {
+ Some(v) => info!("{:?} = {:?}", tag_test_str, v),
+ None => info!("We got nothing from {:?}", tag_test_str),
+ };
+ }
+ };
+
+ match nvs.set_str(tag_test_str, "Hello from the NVS!") {
+ Ok(_) => info!("{:?} updated", tag_test_str),
+ Err(e) => info!("{:?} not updated {:?}", tag_test_str, e),
+ };
+
+ Ok(())
+}