A121 Integration using STM32CubeIDE
USER_LABEL
NUCLEO PIN
GPIO Output Level
Maximum Output speed
SEN_EN1
PB0
Low
Very High
SEN_EN2
PB5
Low
Very High
SEN_EN3
PB3
Low
Very High
SEN_EN4
PA10
Low
Very High
SEN_EN5
PC1
Low
Very High
A121_SPI_SS
PB6
High
Very High
SPI_SEL0
PA4
Low
Very High
SPI_SEL1
PA1
Low
Very High
SPI_SEL2
PA0
Low
Very High
Figure 10: GPIO Configuration
2.6
XE121 Sensor Selection
The XE121 board has support for adding up to 4 extra A121 sensors by using FFC cables and XS121 boards. The selection
of which sensor to communicate with is done in the acc_hal_integration_xe121_multi_sensor.c file.
SPI_SEL2
SPI_SEL1
SPI_SEL0
Sensor Selection
LOW
LOW
LOW
Sensor 1 (XE121)
LOW
LOW
HIGH
Sensor 2 (XS121 S2)
LOW
HIGH
LOW
Sensor 3 (XS121 S3)
LOW
HIGH
HIGH
Sensor 4 (XS121 S4)
HIGH
LOW
LOW
Sensor 5 (XS121 S5)
2.7
XE121 Single Sensor Setup
If the XE121 board is used in a single sensor setup there is no need to connect the following signals SEN_INT2,
SEN_INT3, SEN_INT4, SEN_INT5, SEN_EN2, SEN_EN3, SEN_EN4 and SEN_EN5.
Please note that SEN_SEL0, SEN_SEL1 and SEN_SEL2 need to be kept low to select the sensor onboard the
XE121.
The acc_hal_integration_xe121_multi_sensor.c should be replaced with the acc_hal_integration_xe121_single_sensor.c
file in the STM32CubeIDE project.
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