SENA BLOG

Multiple-connection mode capability is available with new coming release of SD1000 v2.0 firmware.

This document provides the preview of the capabilities of SD1000 v2.0.

1. Overview

With multiple-connection feature, one SD1000 master can connect up to 4 SD1000 slaves simultaneously. There are two different multiple-connections modes available:

- Multi-Drop Mode

One master and up to 4 slaves can communicate with one another simultaneously in both direction.

- Node Switching Mode

Up to 4 slaves remain connected to the master, but only one slave communicates with the master at a time. The master selects which slave unit to communicate with using AT commands..

2. Multi-Drop Mode

2.1 Configuration of Slave Units

- Set SD1000 slave units to MODE3, allowing all Bluetooth connections.

(If you want the units to be connected only with a certain master unit, specify the BD address of the master in register s46, and set connection mode to MODE2.)

2.2 Configuration of the Master Unit

Change operation mode to ‘Multi-Drop’ mode and set BD addresses of each slave SD1000.

(Default mode : SINGLE CONNECT)

By setting Bluetooth operating mode to MODE1, make master SD1000 try to connect all assigned slave SD1000s after booting.

2.3 Results of Multi-Drop Mode Test

Following picture shows the results of Multi-Drop Mode test.

In this test, local echo is enabled, so messages sent or received are both shown in the terminal emulation program screen.

The master sends data to the slaves in the following order.

- Data from Master                       –>        Hello~SlaveA

- Response of Slave A    <–        A_Send_Hello~Master

- Data from Master                       –>        Hello~SlaveB

- Response of Slave B                  <–        B_Send_Hello~Master

- Data from Master                       –>        Hello~SlaveC

- Response of Slave C    <–        C_Send_Hello~Master

- Data from Master                       –>        Hello~SlaveD

- Response of Slave D    <–        D_Send_Hello~Master

3. Node Switching Mode

3.1 Configuration of the Slave Units

- The configuration is the same to the Multi-Drop mode setting.

3.2 Configuration of the Master Unit

Change operation mode to Node Switching Mode and set BD addresses of each slave SD1000.

By setting Bluetooth operating mode to MODE1, the master SD1000 tries to connect all specified slave SD1000s after booting.

3.3 Result of Node Switching Mode Test

Following picture shows the result of Node Switching Mode Test.

One slave SD1000 is connected to a barcode reader by serial, and the other slave SD1000 is connected to a serial printer(COM31) by serial.

First, Master SD1000 receives data from the barcode reader. Next, using AT command of ‘+++ ATO2’, master switches the slave from the SD1000 attached to the barcode reader to the SD1000 attached to the serial printer. Then the master SD1000 sends data  for the serial printer.

For the details of Multiple-connection mode commands, please refer to the user manual.

Note :

In Multi-Drop mode, if more than 300 bytes of data is accumulated in the buffer, buffer is cleared regardless of flow control option. Therefore, when a large amount of data is transferred, data loss may occur. Especially bidirectional communication may cause disconnection or reboot for maintaining multi-drop communication. User has to perform enough tests before actual application to verify if multi-drop mode can be used for his/her real application without any problems.

For reliable connection, forced exit may occur, disconnection message may be displayed in a row.

Node Switching Mode supports hardware flow control and provides almost the same performance as 1:1 single mode.

This entry was posted on Tuesday, September 29th, 2009 at 7:10 am and is filed under Bluetooth. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.