SP1ML Datasheet, PDF (11/27 Pages) STMicroelectronics – SPIRIT1 868 and 915 MHz low power RF modules with integrated microcontroller

SP1ML
Hardware design
2.2
Typical application circuit
In a typical application the SP1ML module is connected to a host MCU using a standard
UART, with transmit and receive signals. This is illustrated in Figure 3.
Figure 3. Typical application circuit
VDD
1
VDD
10uF
VDD
HOST TXD
MCU _RXD
RTS
CTS
GPIO
GPIO
GPIO
GPIO
TXD
SP1ML
TXRXLED
RXD
MODULE
MODE0
SHDN
2
BOOTMODE
RESET
3
SWCLK
SWDIO
RESET
4
GND
VDD
SWD
HEADER
Optional functionality
1. When the TXRX_LED (S24) configuration register (see Table 10) is set to 1, the
TXRXLED signal is an active-low open drain output that can be used to drive an
external LED for status indication when data is sent or received.
2. The MODE0 signal provides a hardware method for switching between command and
operating modes. The SHDN signal allows the module to be placed into a low power
shutdown mode and woken up again.
3. The BOOTMODE AND RESET signals should be connected if module firmware will
need to be updated over the UART interface.
4. To support custom module firmware, the serial wire debug signals need to be
accessible for programming and debugging.
2.3
Layout guidelines
The application PCB requires a flooded ground plane. Care must be taken to ensure there
are no traces or ground planes under the area surrounding the antenna, with the exception
DocID026906 Rev 4
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