Limits on slave latercy and supervisory timeout setting?

Question

Hi, 
 I'm trying to modify the slave latency and supervisory timeout setting, but found sometimes the gap_params_init() will get error after changing. 
 For example, I can set 
 CONN_SUP_TIMEOUT=10000 (10s) 
 MAX_CONN_INTERVAL=200 (ms) 
 SLAVE_LATERCY=10 
 and this setting works OK, 
 but if I change the MAX_CONN_INTERVAL to 500ms it will get error. 
 
 If I set 
 CONN_SUP_TIMEOUT=50000 (50s) 
 MAX_CONN_INTERVAL=200 (ms) 
 SLAVE_LATERCY=10 
 it will also get error. 
 
 My question is , is there a limit about how much are these parameters can be set?

MartinBL · Accepted Answer

Hi, 
 Please refer to the Bluetooth Core specification Version 5.0 | Vol 6, Part B, Ch. 4.5.2 Supervision Timeout: 
 "Connection supervision timeout ( connSupervisionTimeout ) is a parameter that defines the maximum time between two received Data Packet PDUs before the connection is considered lost. The connSupervisionTimeout shall be a multiple of 10 ms in the range of 100 ms to 32.0 s and it shall be larger than (1 + connSlaveLatency ) * connInterval * 2." 
 If you use: 
 CONN_SUP_TIMEOUT=10000 (10s) MAX_CONN_INTERVAL=500(ms) SLAVE_LATERCY=10 
 then CONN_SUP_TIMEOUT is too small (1 + connSlaveLatency ) * connInterval * 2 = 11 sec) . 
 If you use: 
 CONN_SUP_TIMEOUT=50000 (50s) MAX_CONN_INTERVAL=200 (ms) SLAVE_LATERCY=10 
 then CONN_SUP_TIMEOUT is too large (larger than 32 sec). 
 I'm betting it is sd_ble_gap_ppcp_set() that returns NRF_ERROR_INVALID_PARAM when you try to use values outside of spec.

awneil · Answer

Apart from the Bluetooth Specification limits that MartinBL has already pointed out, note that Central platforms may also impose their own restrictions within those limits. 
 See the developer documentation for your Central platform(s). 
 eg, see: https://devzone.nordicsemi.com/f/nordic-q-a/14550/android-acceptable-connection-parameters

Limits on slave latercy and supervisory timeout setting?

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