This step by step guide explains how to configure the PULSE to use an external input clock signal to drive the internal IMU sampling loop.

Please first read the Clock Modes page to understand the available clock modes and options.

Before we start

The PULSE implements the sbgInsRestApi protocol over a serial interface. All available configurations and commands are detailed in the Digital interfaces page. All the examples use the sbgEComApi command line tool.

In this guide, we consider a PULSE connected to a Windows computer on the serial COM12 and using the default 921600 bps baud rate.

The clock mode depends on three different configuration nodes:

  • The event in A configuration '/api/v1/settings/events/eventInA'
  • The clock source option '/api/v1/settings/clock/source'
  • The clock mode setting '/api/v1/settings/clock/mode'

In this guide, we configure each node one by one for the sake of simplicity but you can also send the whole configuration at once.


Event Out A Signal

The Event Out A and Event In A signals are multiplexed on the same hardware pin. As a result, please make sure you disable the Event Out A signal if you would like to use an external clock signal.

Setup Event In A

Send this command to enable the Event In A and to be active on a falling edge:

sbgEComApi.exe -s COM12 -r 921600 /api/v1/settings/events/eventInA/trigger -p -b \"falling\"

The device answer should be:

{"title":"request successful","needReboot":false}

Select the clock source

Send this command to switch from the internal clock source to the external Event In A clock source:

sbgEComApi.exe -s COM12 -r 921600 /api/v1/settings/clock/source -p -b \"eventInA\"

The device answer should be:

{"title":"request successful","needReboot":true}

Configure the clock mode

The PULSE offer two external clock synchronization mode:

  • direct: User has to provide an exact 2 kHz clock to directly drive the pulse sampling & processing loop
  • scaled: User can provide a low frequency clock and down to 1 Hz and the PULSE will align it's sampling & processing loop on it

Send this command to select the scaled mode and just replace scaled by direct to choose the other mode:

sbgEComApi.exe -s COM12 -r 921600 /api/v1/settings/clock/mode -p -b \"scaled\"

The device answer should be:

{"title":"request successful","needReboot":true}

Save New Settings

The PULSE has to be reboot for the new clock mode settings to be applied. You thus have to save the new configuration before rebooting the device using the command below:

sbgEComApi.exe -s COM12 -r 921600 /api/v1/settings/save -p

The device answer should be:

{"title":"request successful","needReboot":true}

You can then reboot the device and the PULSE will wait for a valid external input clock signal to send data.

Software Reboot

The PULSE implements a dedicated command /api/v1/system/reboot to perform a software reboot.