Data Sheet

BDE-BLEM301
Bluetooth 5.1 LE Module
Datasheet
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BDE Technology Inc.
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There are some special considerations regarding using this module, namely:
• RST signal is shared with the MOSI input of the NOR flash. For this reason, RST must not be
driven to GND. When internal Flash is in use, reset functionality is not available.
• The SPI Bus of DA14531 is used for the communication of the BLE SoC with the NOR Flash at
boot time. Three of the four signals are not driven to external module pins. For this reason, a
sensor that utilizes the SPI bus must be assigned (by software) on to the module pins to
communicate with after booting and when NOR Flash is no longer in use. An example is
presented in the following figure.
Figure 8: Example of Connecting a Sensor to the SPI Bus and an MCU to RST and UART
Note that P0_0/RST pin should not be driven while the module is booting from its internal SPI FLASH.
8. Design Guidelines
BDE-BLEM301 comes with an integrated PCB trace antenna. Antenna area is 12.5 x 5 mm. The antenna
is characterized in terms of Voltage Standing Wave Ratio (VSWR) and efficiency.
The PCB trace antenna radiated performance depends on the host PCB layout. The Antenna gain is
better than -1 dBi when mounted on a 50 x 50 mm reference board. Radiation pattern is omnidirectional.
The RF front end has been optimized to achieve the maximum possible efficiency for various mounting
positions of the module on a host PCB. To obtain similar performance, guidelines described in the
following sections should be followed.
8.1. Placement
For optimum performance, the module should be placed at the edge of a host PCB with the antenna
edge facing out. The module can be located on either of the outer corners or the middle of the host PCB
with equivalent performance.
Proximity with copper or laminate next to the PCB trace antenna affects the efficiency of the antenna.
The antenna should have 4 mm free space in all directions. Laminate or copper under the antenna
should be avoided as it severely affects the performance of the antenna. Antenna keep-out area can be
seen in Figure 9.
Metals close to the antenna will cause degradation on antenna performance. The amount of