LR1110
User Manual Rev.1.0
UM.LR1110.W.APP March 2020
23 of 130
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3. Host-Controller Interface
The LR1110 exposes an API which allows the Host controller to communicate with the LR1110 through a set of SPI
commands / responses. The pin BUSY is used as handshake to indicate if the LR1110 is ready to accept a command.
Therefore, it is necessary to check the status of BUSY prior to sending a command.
3.1 Write Commands
During write commands, the LR1110 returns to the host the status registers and the interrupt registers on the MOSI pin,
depending on the length of the command opcode and arguments.
The host sends a 16 bits opcode followed by the required arguments. The BUSY pin is automatically asserted on the falling
edge of the NSS. Once the LR1110 finishes processing the command, the BUSY line is de-asserted to indicate that the device
is ready to accept another command.
Figure 3-1: Write Command Timing Diagram
3.2 Read Commands
Specific Read commands allow to retrieve data from LR1110, such as internal status or geolocation results.
The host sends a 16 bits opcode, followed by the required arguments. The BUSY pin is automatically asserted on the falling
edge of the NSS. Once the LR1110 finished preparing the requested data, the BUSY pin is de-asserted. The host can then
read back the data by sending NOPs (0x00 Bytes) to shift out the data on the SPI.
Figure 3-2: Read Command Timing Diagram
3.3 Status Registers
The LR1110 features 2 status variables Stat1 and Stat2, which allow to determine the status of the LR1110 (the last
command sent, of the device interrupts, of the device operating mode, and of the bootloader) without the need for the host
to send a specific command.
BUSY
NSS
MOSI Op Op Arg0 Arg1 NOP NOP NOP
MISO
Stat1 Stat2 IrqStat(31:24) IrqStat(23:16) Stat1 Rsp0 Rsp1
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