I am performing ESP32 OTA over the GSM. I have found some example code online, modified it slightly based on my board connections and was able to sucesfully perform a firmware update.
I use lilygo ESP32 GSM development board.
However, it frustrates me that I am not capable of understanding what really happens in the code at the low level. I really want to understand before I go any further with my project.
Full code for my OTA update:
#include <Update.h>
#define TINY_GSM_MODEM_SIM800
// Increase RX buffer
#define TINY_GSM_RX_BUFFER 1030
const char apn[] = "omnitel";
const char user[] = "omni";
const char pass[] = "omni";
#define MODEM_RST 5
#define MODEM_PWRKEY 4
#define MODEM_POWER_ON 23
#define MODEM_TX 27
#define MODEM_RX 26
#define LED_GPIO 13
#define LED_ON HIGH
#define LED_OFF LOW
#define SerialAT Serial1
#include <TinyGsmClient.h>
#include <CRC32.h>
#include "FS.h"
#include "SPIFFS.h"
#ifdef DUMP_AT_COMMANDS
#include <StreamDebugger.h>
StreamDebugger debugger(SerialAT, Serial);
TinyGsm modem(debugger);
#else
TinyGsm modem(SerialAT);
#endif
TinyGsmClient client(modem);
const char server[] = "myesptestserver.ddns.net";
const int port = 80;
const char resource[] = "/esp.bin"; //here de bin file
uint32_t knownCRC32 = 0x6f50d767;
uint32_t knownFileSize = 1024; // In case server does not send it
void setup()
{
SerialAT.begin(115200, SERIAL_8N1, MODEM_RX, MODEM_TX);
// Set console baud rate
Serial.begin(115200);
setupModem();
delay(10);
if (!SPIFFS.begin(true))
{
Serial.println("SPIFFS Mount Failed");
return;
}
SPIFFS.format();
listDir(SPIFFS, "/", 0);
// Set GSM module baud rate
delay(3000);
// Restart takes quite some time
// To skip it, call init() instead of restart()
Serial.println("Initializing modem...");
modem.restart();
String modemInfo = modem.getModemInfo();
Serial.print("Modem: ");
Serial.println(modemInfo);
// Unlock your SIM card with a PIN
//modem.simUnlock("1234");
}
void loop()
{
Serial.print("Waiting for network...");
if (!modem.waitForNetwork())
{
Serial.println(" fail");
delay(10000);
return;
}
Serial.println(" OK");
Serial.print("Connecting to ");
Serial.print(apn);
if (!modem.gprsConnect(apn, user, pass))
{
Serial.println(" fail");
delay(10000);
return;
}
Serial.println(" OK");
Serial.print("Connecting to ");
Serial.print(server);
// if you get a connection, report back via serial:
if (!client.connect(server, port))
{
Serial.println(" fail");
delay(10000);
return;
}
Serial.println(" OK");
// Make a HTTP request:
client.print(String("GET ") + resource + " HTTP/1.0\r\n");
client.print(String("Host: ") + server + "\r\n");
client.print("Connection: close\r\n\r\n");
long timeout = millis();
while (client.available() == 0)
{
if (millis() - timeout > 5000L)
{
Serial.println(">>> Client Timeout !");
client.stop();
delay(10000L);
return;
}
}
Serial.println("Reading header");
uint32_t contentLength = knownFileSize;
File file = SPIFFS.open("/update.bin", FILE_APPEND);
while (client.available())
{
String line = client.readStringUntil('\n');
line.trim();
//Serial.println(line); // Uncomment this to show response header
line.toLowerCase();
if (line.startsWith("content-length:"))
{
contentLength = line.substring(line.lastIndexOf(':') + 1).toInt();
}
else if (line.length() == 0)
{
break;
}
}
timeout = millis();
uint32_t readLength = 0;
CRC32 crc;
unsigned long timeElapsed = millis();
printPercent(readLength, contentLength);
while (readLength < contentLength && client.connected() && millis() - timeout < 10000L)
{
int i = 0;
while (client.available())
{
// read file data to spiffs
if (!file.print(char(client.read())))
{
Serial.println("Appending file");
}
//Serial.print((char)c); // Uncomment this to show data
//crc.update(c);
readLength++;
if (readLength % (contentLength / 13) == 0)
{
printPercent(readLength, contentLength);
}
timeout = millis();
}
}
file.close();
printPercent(readLength, contentLength);
timeElapsed = millis() - timeElapsed;
Serial.println();
client.stop();
Serial.println("stop client");
modem.gprsDisconnect();
Serial.println("gprs disconnect");
Serial.println();
float duration = float(timeElapsed) / 1000;
/*
Serial.print("Tamaño de Archivo: ");
Serial.println(contentLength);
Serial.print("Leido: ");
Serial.println(readLength);
Serial.print("Calculado. CRC32: 0x");
Serial.println(crc.finalize(), HEX);
Serial.print("Conocido CRC32: 0x");
Serial.println(knownCRC32, HEX);
Serial.print("Bajado en: ");
Serial.print(duration);
Serial.println("s");
Serial.println("Se genera una espera de 3 segundos");
for (int i = 0; i < 3; i++)
{
Serial.print(String(i) + "...");
delay(1000);
}
*/
//readFile(SPIFFS, "/update.bin");
updateFromFS();
// Do nothing forevermore
while (true)
{
delay(1000);
}
}
void appendFile(fs::FS &fs, const char *path, const char *message)
{
Serial.printf("Appending to file: %s\n", path);
File file = fs.open(path, FILE_APPEND);
if (!file)
{
Serial.println("Failed to open file for appending");
return;
}
if (file.print(message))
{
Serial.println("APOK");
}
else
{
Serial.println("APX");
}
}
void readFile(fs::FS &fs, const char *path)
{
Serial.printf("Reading file: %s\n", path);
File file = fs.open(path);
if (!file || file.isDirectory())
{
Serial.println("Failed to open file for reading");
return;
}
Serial.print("Read from file: ");
while (file.available())
{
Serial.write(file.read());
delayMicroseconds(100);
}
}
void writeFile(fs::FS &fs, const char *path, const char *message)
{
Serial.printf("Writing file: %s\n", path);
File file = fs.open(path, FILE_WRITE);
if (!file)
{
Serial.println("Failed to open file for writing");
return;
}
if (file.print(message))
{
Serial.println("File written");
}
else
{
Serial.println("Write failed");
}
}
void listDir(fs::FS &fs, const char *dirname, uint8_t levels)
{
Serial.printf("Listing directory: %s\n", dirname);
File root = fs.open(dirname);
if (!root)
{
Serial.println("Failed to open directory");
return;
}
if (!root.isDirectory())
{
Serial.println("Not a directory");
return;
}
File file = root.openNextFile();
while (file)
{
if (file.isDirectory())
{
Serial.print(" DIR : ");
Serial.println(file.name());
if (levels)
{
listDir(fs, file.name(), levels - 1);
}
}
else
{
Serial.print(" FILE: ");
Serial.print(file.name());
Serial.print(" SIZE: ");
Serial.println(file.size());
}
file = root.openNextFile();
}
}
void deleteFile(fs::FS &fs, const char *path)
{
Serial.printf("Deleting file: %s\n", path);
if (fs.remove(path))
{
Serial.println("File deleted");
}
else
{
Serial.println("Delete failed");
}
}
void updateFromFS()
{
File updateBin = SPIFFS.open("/update.bin");
if (updateBin)
{
if (updateBin.isDirectory())
{
Serial.println("Directory error");
updateBin.close();
return;
}
size_t updateSize = updateBin.size();
if (updateSize > 0)
{
Serial.println("Starting update");
performUpdate(updateBin, updateSize);
}
else
{
Serial.println("Error, archivo vacío");
}
updateBin.close();
// whe finished remove the binary from sd card to indicate end of the process
//fs.remove("/update.bin");
}
else
{
Serial.println("no such binary");
}
}
void performUpdate(Stream &updateSource, size_t updateSize)
{
if (Update.begin(updateSize))
{
size_t written = Update.writeStream(updateSource);
if (written == updateSize)
{
Serial.println("Writes : " + String(written) + " successfully");
}
else
{
Serial.println("Written only : " + String(written) + "/" + String(updateSize) + ". Retry?");
}
if (Update.end())
{
Serial.println("OTA finished!");
if (Update.isFinished())
{
Serial.println("Restart ESP device!");
ESP.restart();
}
else
{
Serial.println("OTA not fiished");
}
}
else
{
Serial.println("Error occured #: " + String(Update.getError()));
}
}
else
{
Serial.println("Cannot beggin update");
}
}
void printPercent(uint32_t readLength, uint32_t contentLength)
{
// If we know the total length
if (contentLength != -1)
{
Serial.print("\r ");
Serial.print((100.0 * readLength) / contentLength);
Serial.print('%');
}
else
{
Serial.println(readLength);
}
}
void setupModem()
{
#ifdef MODEM_RST
// Keep reset high
pinMode(MODEM_RST, OUTPUT);
digitalWrite(MODEM_RST, HIGH);
#endif
pinMode(MODEM_PWRKEY, OUTPUT);
pinMode(MODEM_POWER_ON, OUTPUT);
// Turn on the Modem power first
digitalWrite(MODEM_POWER_ON, HIGH);
// Pull down PWRKEY for more than 1 second according to manual requirements
digitalWrite(MODEM_PWRKEY, HIGH);
delay(100);
digitalWrite(MODEM_PWRKEY, LOW);
delay(1000);
digitalWrite(MODEM_PWRKEY, HIGH);
// Initialize the indicator as an output
pinMode(LED_GPIO, OUTPUT);
digitalWrite(LED_GPIO, LED_OFF);
}
From what I understand, the following part of the code reads my binary file that is stored in the server and read it into SPIFFS memory:
while (readLength < contentLength && client.connected() && millis() - timeout < 10000L)
{
int i = 0;
while (client.available())
{
// read file data to spiffs
if (!file.print(char(client.read())))
{
Serial.println("Appending file");
}
//Serial.print((char)c); // Uncomment this to show data
//crc.update(c);
readLength++;
if (readLength % (contentLength / 13) == 0)
{
printPercent(readLength, contentLength);
}
timeout = millis();
}
}
Then the updateFromFS() function is executed, which checks whether the binary is all good and then calls another function performUpdate(updateBin, updateSize);
void updateFromFS()
{
File updateBin = SPIFFS.open("/update.bin");
if (updateBin)
{
if (updateBin.isDirectory())
{
Serial.println("Directory error");
updateBin.close();
return;
}
size_t updateSize = updateBin.size();
if (updateSize > 0)
{
Serial.println("Starting update");
performUpdate(updateBin, updateSize);
}
else
{
Serial.println("Error, archivo vacío");
}
updateBin.close();
// whe finished remove the binary from sd card to indicate end of the process
//fs.remove("/update.bin");
}
else
{
Serial.println("no such binary");
}
}
in the performUpdate(updateBin, updateSize), 2 functions from Arduino Update Library are being called ( Update.begin(updateSize) and Update.writeStream(updateSource) ) and that is where I cant follow anymore...
void performUpdate(Stream &updateSource, size_t updateSize)
{
if (Update.begin(updateSize))
{
size_t written = Update.writeStream(updateSource);
if (written == updateSize)
{
Serial.println("Writes : " + String(written) + " successfully");
}
else
{
Serial.println("Written only : " + String(written) + "/" + String(updateSize) + ". Retry?");
}
if (Update.end())
{
Serial.println("OTA finished!");
if (Update.isFinished())
{
Serial.println("Restart ESP device!");
ESP.restart();
}
else
{
Serial.println("OTA not fiished");
}
}
else
{
Serial.println("Error occured #: " + String(Update.getError()));
}
}
else
{
Serial.println("Cannot beggin update");
}
}
I have found this Update library source code : https://github.com/espressif/arduino-esp32/blob/master/libraries/Update/src/Updater.cpp
But it seems that this is beyond my knowledge to understand what really is going on in this code.
First of all, we pass only 1 variable to .begin method, but the function prototype requires more than that:
bool UpdateClass::begin(size_t size, int command, int ledPin, uint8_t ledOn, const char *label)
And then I am trying to understand what happens in function Update.writeStream(updateSource) but cant..
If anyone could shed some light here I would appreciate a lot! Thanks in advance...
