LoRa Basics Modem and LoRa Edge documentation

Scenario - LoRa Basics™ Wi-Fi Passive Scan

Introduction

One of the key features of the LoRa Edge™ system is the ability to scan Wi-Fi signals and provide the measurements to a LoRa Cloud™ processing system to determine the location of an object. Here, we review the requirements for completing a passive Wi-Fi scan by the LR111x chip and for returning the data to the device application.

Compatibility

LoRa Basics Modem(s)

LoRa Edge LR1110 transceiver

Prerequisites/Dependences

Common:

  • Must have an SPI connection to exchange information between the device application and the LR1110 chip.

Prerequisites for LoRa Basics™ Modem:

  • Not applicable

Prerequisites for LoRa Basics Modem-E:

  • No additional requirements

Prerequisites for a Transceiver:

  • No additional requirements

Step-by-Step Procedure

LoRa Basics™ Modem-E

  1. Through the SPI interface, the host MCU calls the Wi-Fi passive scan command (0x0330)

    Note

    • Scan options include: Wi-Fi type (b/g/n), Chan Mask, Acquisition Mode, Max Nb, Nb Scan per Channel, Timeout, Abort on Timeout, and Result Format

    • Depending on the channel mask, number of scans per channel, and the timeout settings, the scan time will vary (for example, it will take about 500ms for six (6) access points on three (3) channels).

  2. When the scan is complete, the EVENT signal on the LoRa Basics Modem-E is set high.

  3. The host MCU calls GetEventsize (command 0x0633) and GetEvent (command 0x0600).

  4. The LoRa Basics Modem-E clears the EVENT signal by asserting it low.

  5. The LoRa Basics Modem-E returns the Wi-Fi scan results.

@startuml passive_wifi_scanbox Device #ADD8E6    participant "End-Device Application" as APP #ADD8E6    participant "LoRa Basics™ Modem-E" as LR1110 #00ADEF    == Passive Wi-Fi Scan == end boxlegend left|=             |= Owner || <#00ADEF>    | Semtech || <#ADD8E6>    | Customer || <#D3D3D3>    | Ecosystem |endlegendAPP -> LR1110 : Passive Wi-Fi scan (command 0x0330)LR1110 -> APP : Event high note right: Event\: Wi-Fi scan doneAPP -> LR1110 : GetEventsize (command 0x0633), \nGetEvent (command 0x0600)LR1110 -> APP : Wi-Fi scan done + Resultsnote right: Scan results ready for \ntransmission or local storageLR1110 -> APP : Event low        @enduml

Transceiver

  1. Through the SPI interface, the host MCU calls the Wi-Fi scan command (0x0300)

    Note

    • Scan options include: Wi-Fi type (b/g/n), Chan Mask, Acquisition Mode, Max Nb, Nb Scan per Channel, Timeout, Abort on Timeout, and Result Format

    • Depending on the channel mask, number of scans per channel, and the timeout settings, the scan time will vary (for example, it will take about 500ms for six (6) Access Points on three (3) channels).

  2. If enabled with WifiScanDone, when the scan is complete, the IRQ signal on the LR1110 is set high.

  3. The host MCU calls WifiGetNbResults (command 0x0305) and WiFiReadResults (command 0x0306).

  4. The LR1110 chip sets the BUSY signal low.

  5. The LR1110 chip returns the Wi-Fi scan results.

  6. If enabled, the LR1110 chip sets the IRQ signal low.

@startuml passive_wifi_scan_trxbox Device #ADD8E6    participant "End-Device Application" as APP #ADD8E6    participant "LR111x Transceiver" as LR1110 #00ADEF    == Passive Wi-Fi Scan == end boxlegend left|=             |= Owner || <#00ADEF>    | Semtech || <#ADD8E6>    | Customer || <#D3D3D3>    | Ecosystem |endlegendAPP -> LR1110 : Passive Wi-Fi scan (command 0x0300)LR1110 -> APP : BUSY signal high note right: IRQ signal high (if enabled)\n Wi-Fi scan doneAPP -> LR1110 : WifiGetNbResults (command 0x0305), \nWifiReadResults (command 0x0306)LR1110 -> APP : GNSS scan done + Resultsnote right: Scan results ready for \ntransmission or local storageLR1110 -> APP : IRQ Signal low (if enabled)@enduml

Used By

MCU, LR111x/LoRa Edge chip

Troubleshooting

  • No suggestions at this time.

References