Multitech MTS2BTA-R Manual de usuario descargar pdf (Pagina 37)

Chapter 2 – AT Commands

Multi-Tech Systems, Inc. SocketWireless Bluetooth AT Commands (S000360H) 37

About Command/Data Mode

1. Fast Data Mode

Fast data mode is currently supported in point to point mode only. There is no such feature in the ATMP

Multi-Point code implementation since the parser needs to be on.

The drawback to this is that once in fast data mode there are limited ways to get out of it like CPU reset,

power down, or strobing PIO(4) for >5ms. The advantage of this mode is that the data being sent does

not have to be evaluated or processed for AT commands and will allow for a faster effective data

throughput of around 250Kbps. To verify you are in fast data mode type +++<cr> it will pass directly

through the UART because the AT Command parser is off. Else the +++<cr> will be accepted because

the AT Command parser is still on and returns “OK”. On the previous 4Mbit legacy modules, the escape

characters were fixed and set to “ATMC”; this is no longer implemented.

2. Command/Data Mode

The Command Mode or Data Mode will slow down the throughput when the radio looks for the AT

commands. One way to allow minimal overhead transmission burden is to perform all configuration

commands, and then place the radio into the fast data mode.

About Byte Gaps and Data Latency

The way Bluetooth is designed and operates random byte gaps of 5 msec to 20 ms are common. Packet size

will vary from transmission to transmission. The faster the UART speed the smaller the byte gap delay.

Effective data payload throughput in fast data mode is approximately 250Kbps and 35Kbps in regular data

mode when the AT parser looks at each character for ASCII valid command scripts in the data stream. The

radio RX has very limited buffering so if you do not use hardware flow control and are transmitting further

distances you will quickly overflow the buffer because of RF retransmissions, etc.

When a Bluetooth connection is made the radio modem goes into regular data mode per the power-up factory

default settings. This enables the user to remotely configure the radio settings via a remote RF Bluetooth

connection. Basically you can setup the radio so no commands are required to be sent from the embedded

side of the radios UART. This will prevent any software embedded firmware development or testing for

legacy systems.

Data Mode Commands

+++ Put Device into Command Mode

This sequence is used to force the radio into command mode state. If the Radio has been placed in Fast

Data Mode this command will have no affect and the typed command will be treated as data. When using

this command allow at least 100ms delay before sending the next AT command.

Format: +++

Return Parameters: If successful an “OK” is returned, or nothing will be returned if already

in command mode or fast data mode.

EXAMPLE:

TYPE: +++<cr>

REPLY: <cr_lf>OK<cr_lf>

Note: This command is only required if the module is RF CONNECTED, it has no effect if the

module is not connected or if it is connected in Fast Data Mode.

SESC Set Command Mode Escape Character

This command sets the radio’s escape character, used to put the radio into command mode.

Format: ATSESC,<ASCII Value>

Parameter: ASCII Value: Integer value of a non extended ACII character

Factory Default: 43 = “+”

EXAMPLE:

TYPE: ATSESC,43<cr>

REPLY: <cr_lf>OK<cr_lf>

<cr_lf>ERROR<cr_lf>

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