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Hardware triggering doc #122

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Updated Hardware triggering documentation with relevant information
thilo-huck Aug 27, 2026
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thilo-huck Aug 27, 2026
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13 changes: 8 additions & 5 deletions docs/dvl/dvl-triggering.md
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Expand Up @@ -9,16 +9,19 @@ The DVL has different options for triggering acoustic pings to perform a velocit

## Hardware triggering

Use the RS232 RX line of the DVL to send a trigger command after enabling hardware triggering in the [configuration](configuration.md#operating-configurations).
Use the RS232 RX line of the DVL to trigger a ping after enabling hardware triggering in the [configuration](configuration.md#operating-configurations).

Once hardware triggering is enabled, transmit a "NUL" ASCII character (Ctrl + @) to send a ping. The trigger is detected on the falling edge of the signal.
The trigger is detected on the falling edge of the RX signal. The signal must then remain low for approximately 78.1 µs before returning high.

<!-- TODO: Engineering review: confirm whether the documented hardware trigger pulse width is 78.1 s +/- 4.3 microseconds or a different unit before publishing the exact value. -->
For a UART connection configured as 115200 baud, 8N1, this pulse corresponds to transmitting a `"NUL"` ASCII character (`0x00`, Ctrl + @).

You can send this trigger signal as often as needed. If the DVL is already transmitting, it discards the signal.
Because the trigger is defined by its pulse timing, sending a `NUL` character at another baud rate may **not** produce a valid trigger.

The trigger can be sent as often as needed. If the DVL is already transmitting or receiving, incoming trigger signals are discarded.

!!! warning
Acoustics must be enabled. If acoustics are disabled, hardware triggering will not work.

Acoustics must be enabled. Hardware triggering will not work while acoustics are disabled.

## Software triggering

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