Host Interaction Mode

In this mode, host interaction varies based on the host interface. Host interaction in SPI/USB and UART/USB-CDC are different. In UART/USB-CDC, boot-up options are menu-based while SPI/USB uses command exchanges. The details are explained below for UART and USB-CDC.

Host Interaction Mode in UART/USB-CDC

This section explains the host interaction mode in UART/USB CDC mode.

Startup Operation

After powering up, the host is required to carry out an Auto Baud Rate Detection (ABRD) operation. After a successful ABRD, the module displays the menu of boot-up options to the host. The host then needs to select the appropriate option.


On power up, the bootloader checks the integrity of the bootup options. If the integrity fails, the bootloader computes the integrity from backup. If integrity passes, the bootloader copies the backup to the actual location. If the integrity of the backup options also fails, the bootup options are reset/cleared. In either of the cases, bootloader bypass is disabled or corresponding error messages are given to the host. In case of integrity failure and when the backup integrity check passes, the "LAST CONFIGURATION NOT SAVED" message is displayed. When backup integrity also fails, “BOOTUP OPTIONS CHECKSUM FAILED" is displayed before displaying the bootup options.

Hyper Terminal Configuration

RS9116W uses the following UART interface configuration for communication:

Baud Rate: The following baud rates are supported by the module: 9600 bps, 19200 bps, 38400 bps, 57600 bps, 115200 bps, 230400 bps, 460800 bps, and 921600 bps.

Data Bits: 8 Parity: None Stop Bits: 1

Flow Control: None

Before powering up the module, follow the sequence of steps as given below:

Figure 1 - HyperTerminal Name Field Configuration


The default baud rate of the module is 115200 bps.

Figure 2 - HyperTerminal COM Port Field Configuration

In the Connect using" field, select the appropriate com port. In the figure above COM3 is selected. Click the "OK" button.

Figure 3 - HyperTerminal Baud Rate Field Configuration

Set the following values for different fields in the above figures as given below:

Auto Baud Rate Detection (ABRD)

The RS9116 automatically detects the baud rate of the Host's UART interface by exchanging some bytes. The Host should configure the UART interface for the following parameters for ABRD detection.

RS9116 uses the following UART interface configuration for communication:

Baud Rate: The following baud rates are supported: 9600 bps, 19200 bps, 38400 bps, 57600 bps, 115200 bps, 230400 bps, 460800 bps, and 921600 bps.

Data Bits: 8

Stop Bits: 1

Parity: None

Flow Control: None

To perform ABRD on the RS9116W, the host must follow the procedure outlined below:

  1. Configure the UART interface of the host at the desired baud rate.

  2. Power on the board.

  3. After releasing the module from reset, the host should wait for 20 ms for the initial boot-up of the module to complete and then transmit 0x1C at the baud rate with which its UART interface is configured. After transmitting '0x1C' to the module, the Host should wait for the module to transmit 0x55 at the same baud rate.

  4. If the '0x55' response is not received from the module, the host has to re-transmit 0x1C, after a delay of 200ms.

  5. After finally receiving '0x55', the host should transmit '0x55' to the module. The module is now configured with the intended baud rate.


Performing ABRD in host interaction mode is a must for USB CDC mode.

Figure 4 - ABRD Exchange Between Host And Module

Below are the boot-up options, firmware upgrade, and firmware loading procedures for the product.

Startup Messages on Power-up

After powering up the module and performing ABRD you will see a welcome message on the host, followed by the boot up options.


Windows HyperTerminal is used to demonstrate boot up/upgrade procedure.

Figure 5 - UART/USB-CDC Welcome Message

Loading the Default Wireless Firmware in the Module

Figure 6 - UART/USB-CDC Default Firmware Loaded

Load Wireless Firmware


  1. In order to use host bypass mode, the user has to select one of the images as the default image by selecting option 5 (Select Default Wireless Firmware).
  2. In Host interaction mode, if there is no option selected after the bootup menu for 20 seconds, then the bootloader will load selected Wireless default image.
  3. If a valid firmware is not present, then a message prompting "Valid firmware not present" will be displayed.

Firmware Upgradation

After powering up the module, a welcome message is displayed.

Upgrade NWP Firmware Image

Figure 7 - Firmware Upgrade File Prompt Message

Figure 8 - Firmware Upgrade File Selection Message

Figure 9 - Firmware Upgrade File Transfer Message

Figure 10 - Firmware Upgrade Completion Message