SP1ML Datasheet, PDF (10/27 Pages) STMicroelectronics – SPIRIT1 868 and 915 MHz low power RF modules with integrated microcontroller

Hardware design
2
Hardware design
SP1ML
2.1
Pin usage
If used with the default firmware and interfaced to a host MCU, at a minimum the SP1ML
module requires power, ground and UART transmit and receive signals to be connected.
Other signals are optional and provide additional functionality. These signals are outlined in
Table 7 below. Unused signals must not be connected.
Pin
Name
Table 7. Module pin usage
Description
Optional
An active-low open drain output that can drive an external LED for
1
TXRXLED TX/RX activity status indication. TXRXLED must be enabled by setting
Yes
the value to 1 in register S24.
2
SHDN
Drive this signal low to put the module into a low power shutdown
mode. Drive the signal high to wake the module.
Yes
3
GPIO0
Reserved for future use, do not connect.
Yes
4
GPIO1
Reserved for future use, do not connect.
Yes
Drive this signal high to force the module into operating mode. Drive
this signal low to force the module into command mode. This enables
5
MODE0
faster switching between modes and obviates the need for escape
Yes
sequences. After setting the MODE0 value, do a RESET to make the
new setting effective.
6
MODE1
Reserved for future use, do not connect.
Yes
7
VDD
Connect to power supply, 1.8V to 3.6V.
No
8
GND
Connect to system ground.
No
9
SWDIO
These signals are the serial wire debug (SWD) interface to the
Yes
STM32L microcontroller, supporting the development and loading of
10
SWCLK
custom firmware.
Yes
11
BOOTMODE
Drive this signal high at power up or reset to start the boot loader and
allow device firmware update over the UART interface.
Yes
12
RESET
Drive this signal low to hold the module in reset. Drive this signal high
to release the module from reset.
Yes
13
TXD
Connect to the host system UART RXD input.
No
14
RXD
Connect to the host system UART TXD output.
No
15
GPIO2
Reserved for future use.
Yes
16
GPIO3
Reserved for future use.
Yes
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DocID026906 Rev 4