User's Manual

Doc ID TBD Rev 0.8 Rev 0.1
9/19
www.st.com
3 Hardware design
3.1 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 the following table. Unused signals must not be connected.
Table 7. Module pin usage
Pin
Name
Description
Optional
1
TXRXLED
An active-low open drain output that can drive an
external LED for TX/RX activity status indication.
Yes
2
WKUP
Drive this signal low to put the module into a low
power shutdown mode. Float or 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
5
MODE0
Drive this signal low to force the module into
operating mode. Drive this signal high to force the
module into command mode. This enables faster
switching between modes and obviates the need for
escape sequences.
Yes
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 STM32L microcontroller, supporting
the development and loading of custom firmware.
Yes
10
SWCLK
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
RTS
Connect to the host system UART CTS output if flow
control is required.
Yes
16
CTS
Connect to the host system UART RTS input if flow
control is required.
Yes