Error: invalid conversion from 'int32_t {aka long int}' to 'const char*' [-fpermissive]

Projects Programming
1

I am new to Arduino and think this might be easy but can't seem to solve it. I am getting an invalid conversion from 'int32_t {aka long int}' to 'const char*'

constexpr int32_t file_maximum_byte_count = (50 * 1024);

BLECharacteristic file_maximum_length_characteristic = BLECharacteristic("3002", BLERead, sizeof(uint32_t));

In my setup I am doing this:

void setup() {
   ...
   blePeripheral.addAttribute(file_maximum_length_characteristic);
   file_maximum_length_characteristic.setValue(file_maximum_byte_count);
   ...
}

I guess I need to convert the file_maximum_length_characteristic to a const char* and on the bluetooth app receives this as an array I believe.

Error:

error: invalid conversion from 'int32_t {aka long int}' to 'const char*' [-fpermissive]
   file_maximum_length_characteristic.setValue(file_maximum_byte_count);
2

I have serious doubts that this is a tutorial. Topic moved.

3

I don't know what version of the ESP32 core you're using, but in v2.06 the only two overloads for the BLECharacteristic class's constructor are:

	BLECharacteristic(const char* uuid, uint32_t properties = 0);
	BLECharacteristic(BLEUUID uuid, uint32_t properties = 0);

Neither of those match what you're attempting to do.

4

The error is happening here:
file_maximum_length_characteristic.setValue(file_maximum_byte_count);

I'm using the library for nRF52.

5

Post the complete error message.

That link doesn't work.

It would have also been helpful for you to tell us you're using nRF52 in your first post.

6

Sorry. Fixed it.

7

How about?

8

For the characteristic you have chosen, the library has these ways to setValue.

setValue(const unsigned char value[], unsigned char length);
 setValue(const char* value);

Try
setValue((uint8_t*)&file_maximum_byte_count, sizeof(file_maximum_byte_count));

1 Like
9

Added the error message above

11

Thank you!!!

12

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