fritzebner asked 6 years ago
UPDATE: the UUID bytes are reversed!! Any ideas why that would be? easy way to undo it?
I can get it to work if i set UUID to 21111111-1111-1111-1111-111111111111 and then tell the iOS app the UUID is 11111111-1111-1111-1111-111111111121
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I’m running the BLE_ibeacon sketch. I’m using the Radius Networks ibeacon app on iOS called Locate.
I can get the iBeacon to be identified, but only if the UUID is a string of constant values, i.e. all 0’s, or all F’s or all 1’s. as soon as i add any other different value, it wont show up. I thought it might be endian related, so tried making the UUID = FF00FF00-FF00-00FF-FFFF-00FF00FF00FF, then tried to detect the UUID = 00FF00FF-00FF-FF00-FFFF-FF00FF00FF00, but that didn’t work. Unfortunately, on iOS you have to specify a UUID before it can be detected, so i can’t see what the UUID really is.
i tried to detect the iBeacon on MACOS high sierra using the app called Beacon Scan from TwoCanoes, but that app never detects the iBeacon regardless of the UUID.
i also tried printing out the beacon bytes over serial, but didn’t get very far – still working out the details of the cpp in arduino stuff.
Help???
Rui Santos Staff answered 6 years ago
Hello, that’s extremely weird… It shouldn’t be reversed and I don’t have a good explanation for that. I also never tried that app “Radius Networks ibeacon”.
Does it work with the app that I recommend in the course “nRF Connect”?
I apologize for taking so long to get back to you.
Thanks for your patience,
Rui
fritzebner answered 6 years ago
nRF connect sees the ESP32, but it doesn’t give me any info other than complete local name and tx power.- i think it wants to connect and exchange bytes, not read iBeacons.
fritzebner answered 6 years ago
do you have any tutorials on how to build arduino libraries?
there is a parameter in the BLEUUID code that tells whether to reverse byte order or not of UUIDs. its set to false now, but maybe if i set to true and rebuilt it would fix?
here is the reference: https://github.com/nkolban/ESP32_BLE_Arduino/blob/master/src/BLEUUID.cpp
fritzebner answered 6 years ago
here is the snippet that reverses the bytes:
else if (value.length() == 36) {
// If the length of the string is 36 bytes then we will assume it is a long hex string in
// UUID format.
m_uuid.len = ESP_UUID_LEN_128;
int n = 0;
for(int i=0;i<value.length();){
if(value.c_str()[i] == ‘–‘)
i++;
uint8_t MSB = value.c_str()[i];
uint8_t LSB = value.c_str()[i+1];
if(MSB > ‘9‘) MSB -= 7;
if(LSB > ‘9‘) LSB -= 7;
m_uuid.uuid.uuid128[15-n++] = ((MSB&0x0F) <<4) | (LSB & 0x0F);
i+=2;
}
}
Rui Santos Staff answered 6 years ago
Exactly… I think nRF Connect only gives that information for a connected client.
That is weird and it shouldn’t happen (it never happened to me), but it looks like that was the problem comes from.
Unfortunately I don’t have any resources on that subject, but I would recommend submitting a issue on Github for that file with all the details that you can provide: https://github.com/nkolban/ESP32_BLE_Arduino