LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
35 of 130
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4. GPIOs
The LR1121 features 13 digital I/Os.
4.1 Interrupts
The LR1121 features numerous interrupt sources, allowing the host to react to a large variety of events in the LR1121 system
without the need to poll registers, therefore allowing power-optimized applications.
The LR1121 interrupts are multiplexed on the DIO9 and/or DIO11 pin. When the application receives an interrupt, it can
determine the source by using command GetStatus(...). The interrupt can then be cleared using the ClearIrq(...)
command.
Command SetDioIrqParams(...) configures which interrupt signal should be activated on the DIO9 and/or DIO11
interrupt pins.
The status of the LR1121 interrupts can be read using command GetStatus(...), but they are also returned by the
LR1121 to the host on the MISO signal during the SPI transactions via the IrqStatus bytes, simultaneously with the command
arguments. Therefore, the number of IrqStatus sent by the LR1121 during the SPI commands depends on the number of
arguments. Refer to Section 3. Host-Controller Interface for additional information.
Table 4-1: Digital I/Os
I/O Description
DIO0 Used for BUSY signalling, and is mandatory to properly handle the host controller interface.
DIO1 to DIO4 Dedicated to the SPI interface signals NSS, SCK, MOSI and MISO respectively.
DIO5, DIO6, DIO7 Can control external RF switches or LNAs on the RFIO-HF and sub-GHz RF paths.
DIO8
Can control external RF switches or LNAs on the RFIO-HF and sub-GHz RF paths.
Can be used as a 32.768kHz source to host controller if a 32.768kHz crystal oscillator is connected to DIO10 and
DIO11.
DIO9
Dedicated to LR1121 interrupts. It is recommended to connect DIO9 to the host controller for the lowest-power
applications. DIO11 can be used as another interrupt pin if no 32.768kHz crystal oscillator is used.
DIO10
Can control external RF switches or LNAs on the RFIO-HF and sub-GHz RF paths.
Can be used as connection pins for an external 32.768kHz crystal oscillator as an RTC source.
DIO11
Can be used as connection pins for an external 32.768kHz crystal oscillator as an RTC source.
Can be used as an input pin if the 32.768kHz signal is fed by the host controller. In this case DIO10 must be left
unconnected.
Can be used as another interrupt pin if no 32.768kHz crystal oscillator is used.
NRESET
Can cancel on-going functions of the LR1121, and reset all HW and FW. Although a device restart is also possible
through host controller commands, it is recommended to allow the host controller to control this signal.
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