How to change and save the I2C address

[dizcza]

Subject of the issue

The saveConfiguration comments the following docs:

Save current configuration to flash and BBR (battery backed RAM)

This, however, isn't true.

Your workbench

• What development board or microcontroller are you using? ESP32
• What version of hardware or breakout board are you using? NEO-M8P
• How is the breakout board wired to your microcontroller? I2C
• How is everything being powered? YES

Steps to reproduce

    myGNSS.setI2CAddress(0x43);
    Serial.printf("saveConfiguration %d\n", myGNSS.saveConfiguration());  // prints 1 as expected

Then ping and you should see 0x43. And I do see 0x43 until a power reset, which resets the device address to its default value, 0x42.

Expected behavior

Settings are saved in flash

Actual behavior

Settings are not saved in flash

---

I noticed that you don't specify the deviceMask and set the packet length to 12. I tried changing your function

// Save current configuration to flash and BBR (battery backed RAM)
// This still works but it is the old way of configuring ublox modules. See getVal and setVal for the new methods
bool SFE_UBLOX_GNSS::saveConfiguration(uint16_t maxWait)
{
  packetCfg.cls = UBX_CLASS_CFG;
  packetCfg.id = UBX_CFG_CFG;
  packetCfg.len = 13;
  packetCfg.startingSpot = 0;

  // Clear packet payload
  memset(payloadCfg, 0, packetCfg.len);

  packetCfg.payload[4] = 0b11111; // Set any bit in the saveMask field to save current config to Flash and BBR
  packetCfg.payload[5] = 0b11111;
  packetCfg.payload[12] = 0b10111;

  return (sendCommand(&packetCfg, maxWait) == SFE_UBLOX_STATUS_DATA_SENT); // We are only expecting an ACK
}

but this didn't help either.

Any clue?

[PaulZC]

Hi Danylo (@dizcza ),

You are trying to do the saveConfiguration too quickly - before the new address has taken effect. Please look at Example9.

The steps are:

• Change the I2C address with myGNSS.setI2CAddress(0x43);
• Wait 2 seconds
• re-begin the GNSS with the new address (myGNSS.begin(Wire, 0x43);)
• myGNSS.saveConfiguration();

I hope this helps,
Paul