fs.writeFileSync() not working with serial link

Thanks to Wilberforce I was able to write a constant string to flash memory. While a constant string is nice, my long term goal is to serve a single page app from flash or a SD card with a file size of 1, 2MB or more. My next baby step was to write a single file of ~800 bytes to flash. Unfortunately after dropping my baud all the way down to 9600 to send a file in binary form to my ESP32, I still lose arbitrary blocks of data. It might be 1 to 20 bytes, but it means I am a long way from sending 200-500 KB file to the my ESP32 flash or SD card. Here's my code(mangled from over a week of hacking) and sample file. The need to write data from a serial link is not only for saving server files, but also for being able to save production data from other devices.

var formatFlashDrive = false;
var writeFile = true;

Serial2.setup(9600, { tx: D17, rx: D16 });
var fileWriteStarted = false;
var fileName = 'index.html';
var fs = require("fs");
var intervalID, existingBlinkRate = 0, timerCount = 0;
Serial2.print("Are you there?");

if(formatFlashDrive){
  console.log('Formatting FS - only need to do once');   
  try {
    console.log("Flash Files: ",fs.readdirSync());
    } catch (e) { 
      console.log('Uncaught Error: Unable to mount media : NO_FILESYSTEM'.e);
       E.flashFatFS({addr : int=0x300000, sectors : int=256, format : bool=false }); 
  }
}
if(!writeFile){console.log("Ready to write to fs");}
if(!writeFile){
  console.log("Reading index.html from flash");
  try{
    console.log(fs.readFileSync("index.html")); // prints "Hello World!!!"
    Serial2.write(fs.readFileSync("index.html"));
  }catch(e){
    console.log("File Read Error = ",e); 
    Serial2.write('File Read Error');
  }
  //flashLED(10);
}
Serial2.on('data',function(data){
  if(!writeFile)return;
  if(!fileWriteStarted){ 
    setTimeout(function(){
      console.log('Reading ',fileName);
      Serial2.write(fs.readFileSync("index.html"));
    },2000);
    fileWriteStarted = true;
    console.log('Writing data');
    fs.writeFileSync(fileName,data);
    return;
  }
  fs.appendFileSync(fileName, data);
  console.log('Appending data');
});

1 Attachment

• ws.html