Using ESP32 as a Serial to BTSerial bridge (ala HC-05)?

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1

I am attempting to use a ESP32 as a serial BT bridge, in lieu of a HC-05 as the HC-05 just can't handle the higher data rates and update frequency I'm using with my GPS module. I have zero programming knowledge, so I've been searching high and low for some already made scripts to no avail. The closest I've found are a 7-year old script that needs to be compiled (way over my head), and another script that I've tried that doesn't seem to work, it just sits there outputting a single period once every second to the serial monitor.
I've manged to cobble together what I think is a working script from 2 other examples ( 1 and 2 ), and all seems fine in the serial monitor, except when I try to use the RTK/NTRIP stream. I'm not really sure if it's working correctly, as all I see is jibberish in the serial monitor, similar to what one would see with a wrong Baud rate, or Binary data trying to be displayed as text, if that makes any sense. AFAIK, a NTRIP stream would be binary data, so I don't know if it being passed through correctly.
This is the code I've spliced together. All I am trying to do, is pass the serial output of the GPS, to the Serial2 input, out to the BTSerial output, then the BTSerial input, to the Serial2 output to the GPS module, and echoing both to the serial monitor.

#include "BluetoothSerial.h"

#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run `make menuconfig` to and enable it
#endif

// Create an instance of the HardwareSerial class for Serial 2
HardwareSerial HWSerial0(0);
HardwareSerial gpsSerial(2);
BluetoothSerial SerialBT;

void setup(){
  HWSerial0.begin(115200);    //ESP32 Serial Monitor
  SerialBT.begin("ESP32test"); //Bluetooth device name
  // Start Serial 2 with the defined RX and TX pins and a baud rate of 115200
  gpsSerial.begin(115200, SERIAL_8N1, 16, 17);
  HWSerial0.println("Serial 2 started at 115200 baud rate");
}

void loop(){
  if (gpsSerial.available() > 0){
    // get the byte data from the GPS
    char gpsData = gpsSerial.read();
    SerialBT.write(gpsData);
    HWSerial0.print(gpsData);
  }
  if (SerialBT.available() > 0) {
    char rtkData = SerialBT.read();
    gpsSerial.write(rtkData);
    HWSerial0.print(rtkData);
  }
//  delay(10);
}
2

I use the HC-06 as a serial to BT unit. It works fine at 115200 Baud with a PC, MCU or GPS unit as the UART serial data source.

Try to describe more clearly what it is that you want to do, and what the problems seem to be.

3

HC-05 can't handle 115200 buad rate reliably, or anything higher then that at all. It will eventually disconnect the BT connection when running at high buad rates. GPS updates greater then 3Hz will also result in disconnects, and even the HC-05 "locking up", requiring the HC-05 to be powered down for a minute or so to reset. Hence why I want to use a ESP32 in place of a HC-05 instead.
I'm not really sure what else to add to what I'm trying to do. I'm trying to use RTK/NTRIP data for centimeter accuracy at up to 10Hz rates (my GPS module is RTK capable and up to 10Hz rates). I'm just trying to use the ESP32 as the SerialBT bridge, instead of using a HC-05. As I said, I'm not a programmer, so I don't know if the code I'm using is correct for that purpose. And I dont know if the binary RTK/NTRIP data is going through correctly. Does the ESP32 need to handle binary data differently when going over serial?

4

Like I said, I have no problem with the HC-06.

I'm trying to use RTK/NTRIP data for centimeter accuracy

Evidently, what you are really trying to do is merge two serial data streams to some device that will process the serial data and apply NTRIP corrections to data from an RTK enabled GPS receiver.

If that is correct, then the go-to source for information on that topic is Sparkfun. They have a very active forum and excellent getting started guides. Plus they sell the gear.

5

HC-06 is the same as the HC-05, other then the HC-06 supports Slave only, while HC-05 can be switched between either Master or Slave mode (and the AT commands are slightly different). Yes, they can support up to 460800 baud rates, but they most certainly aren't capable of actually handling that much data constantly. I've been using the HC-05 for years with various GPS modules testing various data rate configurations, so I know that much about them. They work fine for some light work, but can't handle anything more then that.

And I'm not trying to perform off-line RTK calculations if that is what you are talking about. The GPS module does real time RTK solution itself. The Serial monitor in the code is just that, a monitor so I can see when its hooked up to my PC that data is actually going through the bridge, nothing more. I am not a programmer, I just want to make sure that code I'm using is working correctly and as intended: Serial2 bridge to SerialBT. Data comes in Serial2, gets echoed out of SerialBT. Data comes in SerialBT, gets echoed out to Serial2.