User's Manual

BMD-100 Module Datasheet
Bluetooth 4.1 LE
1/5/2014
BMD-100-DS-V0.5 PRELIMINARY Page 7 of 17
The primary high frequency clock is a 32 MHz crystal oscillator. There is also a fast starting 12 MHz ring
oscillator that provides the clock while the crystal oscillator is starting up. Frequency tolerance of the high-
speed crystal is ±30 ppm.
The low frequency clock is used in Low Power mode and can be supplied either by a 32.7kHz oscillator that
uses an external crystal and guarantees up to ±50 ppm frequency tolerance, or by a ring oscillator with
maximum ±500 ppm frequency tolerance, which does not require any external components.
32.768 kHz Crystal Specification Requirements
Symbol
Parameter
Typ.
Max.
Unit
f
nom
Crystal frequency
32.768
-
kHz
F
tol,BLE
Frequency tolerance
-
±50
ppm
P
D
Load Capacitance
-
0.1
μW
Table 7 - 32.768 kHz Crystal
32.768 kHz Oscillator Comparison
Symbol
Parameter
Typ.
Max.
Unit
f
nom
Crystal frequency
37.4
-
kHz
F
tol,BLE
Frequency tolerance
-
±500
ppm
Table 8 - 32.768 kHz Oscillator
7.5. Note
Additional electrical characteristics and current consumption data can be found on the BlueNRG-MS datasheet
provided by STMicroelectronics at www.st.com.
8. Application controller interface
The application controller interface is based on a standard SPI module with transfer rates up to 8
Mbits/s. The application controller Interface defines a software protocol providing functions to
access all the services offered by the layers of the embedded Bluetooth stack. The ACI
commands are described in the BlueNRG-MS ACI command interface document provided by
STMicroelectronics at www.st.com.