Serial Communication App Header Transparent Mode

Overview

Enabled by default.

When arbitrary data is input to the transmitting terminal, the receiving terminal outputs data with auxiliary information in a specific format.

By default, data input on the transmitting side is separated by CRLF and data before CRLF is sent.

For example, entering Hello<Enter> on the transmitting side results in output Hello with auxiliary info on the receiving side. The transmitting side also outputs a message indicating transmission completion.

[Transmitting side]

Hello  <- input
;U;00004;219;0x820163B2;000;000;0,1,Hel...;6E;  <- output

[Receiving side]

;U;00003;000;0x820163B2;255;000;Hello;42;  <- output

The auxiliary information output by the receiving side includes the source address, received signal strength, checksum, etc. The format of the auxiliary information can be customized.

Distinction between Parent and Child Devices

Header Transparent Mode does not distinguish between parent and child devices.

If the Application ID and frequency channel are the same, data input to any terminal is sent to other terminals.

Identification of Source

The header on the received data includes the logical device ID and serial ID of the sender.

Output Format on Receiving Side

The output format is represented as semicolon (;) separated fields.

[Example output in default state]

;U;00777;120;0x81025A17;120;013;HELLO;79;

This output can be interpreted as follows.

Customization by Header Format

The output format on the receiving side follows the header format.

Changing the header format customizes the content of the auxiliary information output and the checksum calculation range.

The header format can be changed via the interactive mode command h: set header format.

Simplest Format

The simplest header format is *\n. It outputs the received data with CRLF line endings.

 h: set header format [*\n]

When sending HELLO in this case, it behaves as follows.

[Receiving side]

HELLO<CR><LF> or HELLO<LF>

[Transmitting side]

HELLO<CR><LF>

Special Characters in Header Format

You can customize the output by including the following special characters in the header format.

General

Characters following \ (backslash)

Characters following %

Checksum Calculation

The checksum is calculated by XOR (exclusive OR) from the start of the data or from the position indicated by < in the header format up to just before %X or %x.

Example in Default State

The default header format is ;U;%t;%i;0x%A;%q;%s;<*;%X;\n, where the checksum calculation range is *;.

That is, when sending HELLO, the binary data HELLO; is targeted, resulting in checksum 0x79.

[Verification code in Python]

from functools import reduce

def main():
    data = "HELLO;"
    checksum = reduce(lambda x, y: x ^ y, data.encode("ascii"))
    print(f"{data} -> {hex(checksum)}")

if __name__ == "__main__":
   main()  # HELLO; -> 0x79

Other Examples

For example, consider the header format ;%I;*;%X.

Since < is not specified, the checksum calculation range is ;%I;*;.

That is, when sending HELLO, the binary data ;000;HELLO; is targeted, resulting in checksum 0x49.

[Verification code in Python]

from functools import reduce

def main():
    data = ";000;HELLO;"
    checksum = reduce(lambda x, y: x ^ y, data.encode("ascii"))
    print(f"{data} -> {hex(checksum)}")

if __name__ == "__main__":
   main()  # ;000;HELLO; -> 0x49

Transmission Trigger

There is no format on the transmitting side input, but data is split and transmitted packet by packet.

Therefore, the following transmission triggers must be considered.

• When timeout after data input occurs
• When input data reaches the minimum data size
• When a transmission trigger character is received

Transmission trigger settings are specified via the interactive mode k: set transmission trigger item.

Example Setting

To set the transmission trigger character to LF, minimum data size to 8 bytes, and timeout to 30 ms, use the following settings.

 m: set UART mode (E)
 k: set Tx Trigger (sep=0x0a, min_bytes=8 dly=30[ms])
 o: set option bits (0x00000100)