Host-Controller Interface; Write Commands; Read Commands; Status Registers - Semtech LR1110 User Manual

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.
BUSY
NSS
MOSI Op
MISO Stat1

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.
LR1110
User Manual Rev.1.0
UM.LR1110.W.APP March 2020
Op Arg0 Arg1
Stat2 IrqStat(31:24) IrqStat(23:16)
www.semtech.com
NOP NOP NOP
Stat1 Rsp0 Rsp1
23 of 130
Semtech