How to pulse soundcard digital output on sound start/stop

[rachelmcassidy]

Hello,

I am referring to the registers in https://harp-tech.org/api/Harp.SoundCard.html to set the behavior of my soundcard digital outputs. My goal is to generate a brief TTL pulse on sound onset and sound offset, but I'm having a few problems controlling it:

1. When I configure an output to HighWhenSound, this works as expected. However, when I try to overwrite this configuration using any of the other DigitalOutputConfiguration options, it still goes high when the sound is on. If I reset the soundcard using the bootloader or by powering on and off, this does not reset the configuration.
2. When I configure an output to Pulse100MsWhenStart, nothing happens. What is the intended behavior of this setting? Should it go high for 100 ms when the sound starts, or does this mean something else?
3. I'm not sure how to use the following registers: PulseDO, OutputSet, OutputClear, OutputToggle, OutputState. Do these only work with certain digital output configuration payloads? What is the correct input for these nodes in Bonsai?

Thanks for your help!
Rachel

[banchan86]

Hi @rachelmcassidy!

Unfortunately, some of the registers on the SoundCard were planned during development but not implemented. There is a PR to clean up unused registers in the firmware and update the Bonsai interface at harp-tech/device.soundcard#20 and harp-tech/device.soundcard#28, but those might take a while to make it into a release.

Practically, I think the only digital output configuration that might work in the current firmware and interface is HighWhenSound. It seems like the pulse modes were not implemented.

You can use OutputSet and OutputClear to toggle the digital outputs within Bonsai. Set will put it to HIGH and Clear to LOW, and you need to specify which DO channel to write in the property (e.g. DO0). Just keep in mind that these are subject to Windows non-RTOS latencies and will not reflect exactly when the device played the sound if you are using the same events to trigger sound playback. The snippet below, for instance, will toggle it on keypresses:

[rachelmcassidy]

Thanks, that's very helpful! Pulse onset timing is more important than duration in my case so I think I'll be able to combine HighWhenSound and OutputClear with a short delay after triggering the sound for the onset pulse.

One more question though - How can I clear the HighWhenSound configuration from a DO channel? Once that's set I can't find a way to revert it.

[banchan86]

Hi @rachelmcassidy, that workaround sounds perfect to me! I also can't figure out how to clear the HighWhenSound configuration; unfortunately, that functionality might be part of the register clean-up and fix. For others who might stumble upon the thread in the future, I will also note that HighWhenSound only works on DO0 for the moment.