How to use SPIFFS for ESP32 with Platform.IO
One of my pet projects is a controllable power supply based on the ESP32 with a web interface (GitHub repository: https://github.com/vshcryabets/Esp32AdjPsu). Previously, I created simple web pages directly in the code using C++. However, in this project, I realized that working this way is not usable — I should separate the firmware code from the web application code. Most often, the SPI Flash File System (SPIFFS) is used for this (official documentation here - https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/storage/spiffs.html). SPIFFS allows to store data as separate files that can be both read and written.
What is the size of SPIFFS? Let’s take a look at the typical flash memory layout in the case of a 4 MB flash (https://github.com/espressif/arduino-esp32/blob/master/tools/partitions/default.csv):# Name, Type, SubType, Offset, Size, Flags
nvs, data, nvs, 0x9000, 0x5000,
otadata, data, ota, 0xe000, 0x2000,
app0, app, ota_0, 0x10000, 0x140000,
app1, app, ota_1, 0x150000,0x140000,
spiffs, data, spiffs, 0x290000,0x160000,
coredump, data, coredump,0x3F0000,0x10000,About a third of the memory is allocated for SPIFFS, specifically 0x160000 = 1408 KB.
Since I’m using PlatformIO, the instructions will be for this environment. In the project root, create a data folder:
In the data folder, we will create an index.html file with the following content:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>
<h1>Test page ESP32 plus SPIFFS</h1>
</body>
</html>
Test scatch code:
#include
#include
#include
WebServer server(80); // out http server
void handle_OnIndex()
{
// Let’s check if such a file exists:
if (SPIFFS.exists("/index.html")) {
// Open the file and pass its contents as a response.
File file = SPIFFS.open("/index.html", "r");
server.streamFile(file, "text/html");
file.close();
} else {
server.send(404, "text/plain", "File Not Found");
}
}
void setup() {
Serial.begin(9600);
if(!SPIFFS.begin(true)){
Serial.println("SPIFFS failed");
return;
}
// Let’s connect to the WiFi network.
WiFi.begin("wifiname", "wifipassword");
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.print("Connected ");
Serial.println(WiFi.localIP());
server.on("/index.html", handle_OnIndex);
server.begin();
}
void loop() {
server.handleClient();
}
pio run --target buildfsOr use the PlatformIO Menu to simplify the process:
After the image creation is complete, the console should display SUCCESS. This means the SPIFFS image is ready for uploading.
To upload it, either use the command:pio run --target uploadfsOr, once again, this can be done through the PlatformIO Menu:
Important:
- You can rebuild and upload the SPIFFS image as many times as needed. It does not affect the main firmware.
- Make sure that the image size does not exceed the allocated space in the partition table (in this case, 1408 KB).
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