Microchip Technology RN4870 - Page 24

RN4870/71 Bluetooth
®
Low Energy Module User’s Guide
DS50002466A-page 24  2016 Microchip Technology Inc.
2.4.23 ST,<hex16>,<hex16>,<hex16>,<hex16>
This command sets the initial connection parameters of the central device for future
connections. The four input parameters are all 16-bit values in hex format. To modify
current connection parameters, refer to Action command T (2.6.29).
The corresponding Get command, GT, returns the desirable connection parameters set
by command ST when connection is not established. Once the connection is estab-
lished, the actual connection parameters displays in response to command GT.
Connection interval, latency and timeout are often associated with how frequently a
peripheral device must communicate with the central device, therefore, closely related
to power consumption. The parameters, range and description are listed in Tab l e 2-7 .
Apple
®
iOS
®
devices have the following special requirements for these parameters.
• Interval >= 16
• Latency <= 4
• Max_interval - min_interval >= 20
• Timeout <= 600
• (Interval + 16)*(Latency + 1) < Timeout * 8/3
TABLE 2-7: CONNECTION PARAMETERS
Parameter Range Description
Minimum Interval 0x0006 - 0x0C80 The minimum time interval of communication
between two connected devices.
Unit: 1.25 ms.
Maximum Interval 0x0006 - 0x0C80 The maximum time interval of communica-
tion between two connected devices.
Unit: 1.25 ms. Must be larger or equal to Min-
imum Interval.
Latency 0x0000 - 0x01F3
must be less than
(Timeout*10/Inter-
val*1.25-1)
The maximum number of consecutive con-
nection events the peripheral device is not
required to communicate with the central
device.
Timeout 0x000A - 0x0C80 The maximum time allowed between raw
communications before the link is considered
lost. Unit: 10 ms.
Default: 0006,0000,0200
Example: ST,0064,0002,0064 // Set the interval to be 125 ms, latency to be
// 2 and timeout to 1 second
Response: AOK
ERR
// Success
// Syntax error or invalid parameter