Bluetooth connection parameters

[jon]

I am working with nRFx modules and have a few questions about updating parameters. I started my project with an example and modified what I needed. However, I am not sure if the parameters are getting set when I change them. Currently I go into main.c and change the following parameters:

#define MIN_CONN_INTERVAL                          MSEC_TO_UNITS(20, UNIT_1_25_MS)           
#define MAX_CONN_INTERVAL                         MSEC_TO_UNITS(75, UNIT_1_25_MS)           
#define SLAVE_LATENCY                                  0                                         
#define CONN_SUP_TIMEOUT               
#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000, APP_TIMER_PRESCALER)  
#define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000, APP_TIMER_PRESCALER) 
#define MAX_CONN_PARAMS_UPDATE_COUNT    3                                
#define TX_POWER_LEVEL                                4      

If I change these parameters, specifically the first three (connection interval, slave latency, and connection supervision timeout), will they automatically be set on with the central? I am currently connecting to a windows 10 device and trying to figure out if the parameters are being updated and if not, why? How would I check to see if they are getting updated?

[endnode]

What project you use? There are like hundred main.c files in SDK;) Normally these constants are indeed used in the code when you recompile and load it to the board so they should be used. The question is what you expect to happen;) Normally there is no debugging on Link Layer on systems like smart phones or Windows boxes so the usual way is to get RF analyzer/sniffer and see what is happening in the air.

[endnode]

No, they are not used when the connection starts because there is simply no way how would Master (Central) know these. They are not broadcasted (no space). However Master can (and should) read them is Peripheral Preferred Parameters Characteristic and Peripheral also can use Peripheral Connection Parameters Update procedure.

I'm afraid the problem here is the perception which leads you to wrong questions. I guess it's safe to say that these parameters are used but that's not saying that you can automatically achieve what you want. Which brigs us to the right question (from my point of view;): what do you want exactly to achieve? Do you want to force Master (Central) to certain connection parameters? Do you want to increase bandwidth? To lower latency? Do you want to achieve that with every peer (another nRFx board, phones, PCs...)? Maybe you fiddle with the thing which won't help you.