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Device configuration and monitoring, 1 control interfaces, 2 command protocol – DekTec DTM-3237 DVB-S2 Receiver User Manual

Page 14: 1 control interfaces 4.2 command protocol

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DTM-3237 – OEM DVB-S2 Receiver with DVB-ASI Output

User Manual

14

4. Device Configuration and Monitoring

4.1 Control interfaces

The DTM-3237 can be configured and monitored using USB, I

2

C and LVTTL serial control port. The

I

2

C address and LVTTL serial control port baud rate can only be configured through the USB interface,

e.g. with Dtm3237Util. It is not required to select between the interface of your choice (USB, I

2

C and

LVTTL serial control port): The DTM-3237 will automatically use the interface on which it detects

activity.

The default I

2

C address is 0x60.

The default LVTTL serial control port baud rate is 9600.

The USB interface is implemented as USB to serial emulator and therefor the USB and LVTTL serial

control port protocol are the same. The baud rate for the USB serial emulator is 256000.
All control interfaces use the same command and response protocol that is described below.

4.2 Command protocol

Commands and responses are wrapped into a frame structure that contains address, category, setting,

read/write, index and data (optional). The DTM-3237 accepts uppercase and lowercase characters,

but will always respond in uppercase.

4.2.1 Command protocol on USB and LVTTL serial control port

Field

Format

Description

Start

ASCII character

STX (0x02)

ASCII “start of text” character

Address

2 hex digits

2

8-bit address

3

Category

2 hex digits

Selects a “category” of settings

Setting

2 hex digits

Selects a setting within the selected category

Read/Write ASCII character

‘R’ or ‘W’

‘R’ for read and ‘W’ for write

Index

4 hex digits

Provides an extra index parameter, e.g. to indicate the

channel number

4

Data

n hex digits / n

ASCII characters

The data written or read. The data length is variable for

each setting. In case of a write operation, the data is a

(negative) acknowledgement

Checksum

2 hex digits

This is the least significant byte of the two’s complement

5

sum of all characters in the message, excluding the STX and

ETX characters and the checksum itself

End

ASCII character

ETX (0x03)

2

Hex digits are the ASCII characters 0…9 and A…F, concatenated to form a single hexadecimal value.

3

The DTM-3237 only supports LVTTL serial control port and USB, so no address is necessary and therefor this value

doesn’t care.

4

The DTM-3237 supports a single channel only, so when index is used as a channel number, it’s always 0.

5

Invert all bits and add one.