How to correctly generate UUIDs-128 for user services and chars.?

[Martin]

I know it was asked and I was searching but I didn't find a clear answer about that. I know that I can generate any random 128bit UUID for all my user services & characteristics. But there are at least 5 algorythms how to generate an UUID according to wiki. I tried to download M$ uudigen.exe and run uuidgen on our linux server and both give me random UUIDs (type 4). But BLE base UUID is type 1 that is less random and it allows to mask first 32b to use them for incremental short UUIDs

Also in one of Nordic examples I can see this: #define LBS_UUID_BASE {0x23, 0xD1, 0xBC, 0xEA, 0x5F, 0x78, 0x23, 0x15, 0xDE, 0xEF, 0x12, 0x12, 0x00, 0x00, 0x00, 0x00} #define LBS_UUID_SERVICE 0x1523 #define LBS_UUID_LED_CHAR 0x1525 #define LBS_UUID_BUTTON_CHAR 0x1524

This base UUID was also masked so four last bytes are zero. I'm not sure about byte order, is it right that 1st byte of APP_UUID_BASE is the last byte of UUID in string format as I see from generator? If it was a random UUID then it become non-random after masking (I can generate many UUIDs that will differ only in last 4 bytes and if I zero them I got same UUID - that are no longer UUIDs).

So I guess that version 1 of UUID algorythm should be used (MAC+time), then some part of UUID remains constant and I can safely mask the part occupied by some low bytes of time, am I right? What program do you reccomend for UUID ver 1 generation? I found this Python script that seems doing it well, so can I then mask the beginninig 32bits and use as my UUID_BASE for entire project just incrementing the first 32b part when need a new service or characteristic?

[VIJAY RAMNANI]

hello, i have gone through above things. now i want to edit uuid ...where i have to make changes ..where will i get the file to change the base address?? please help.. thank you

[Martin]

It depens on what sources you started, in BLE LBS it is in file BLE_LBS.H at the beginning: #define LBS_UUID_BASE {0x23, 0xD1, 0xBC, 0xEA, 0x5F, 0x78, 0x23, 0x15, 0xDE, 0xEF, 0x12, 0x12, 0x00, 0x00, 0x00, 0x00} it's stored as little endian, so if you look at UUID in usual visual form (gropus separated by dashes) it will start by 00000000 and end with 23 byte... You can use nrfgo studio to generate your own UUID.