Percussa SSP Update: Anodized Front Panel Prototypes & More

via the Percussa SSP kickstarter

"Anodized front panel prototypes; Audio inputs, programmable logic, Buttons, Encoders and More!

Hi everyone!

First of all we wish you a happy and successful 2018!

We continued working during the holidays, on the bringup of the SSP hardware: as I wrote in my last update, we still had some work to do on the audio inputs. On the Percussa engine there are only 2 inputs, but the SSP has 16 inputs, and we are using programmable logic to make that possible. So we had to test and debug the programmable logic and our driver code.

Below you can see a photo of my test setup. I've connected my logic analyzer to a few of the data lines of the bus we are using to connect to the programmable logic. One of the issues I had was that the reset pulse for the programmable logic was too short, so I had to figure out what was going on and then make adjustments to make sure it gets properly reset.

I also hooked up a few wires to the data bus so I could monitor if the data transfer was actually happening or not. After some debugging and a few fixes here and there we got the 16 inputs working. Over the next weeks we'll be further testing the inputs and outputs for DC performance. What's really exciting here, is that all 16 inputs are capable of handling audio and CV signals, DC coupled, up to 192kHz and with 32-bit resolution!

We also received the front panel prototypes back from our anodization and engraving subcontractor (photos below). We assembled the front panels with the SSP PCB as you can see below. Everything fits well.

Besides the front panel, we also received our heat sink prototypes. We are doing a custom aluminium heatsink which sits on top of the CPU module, protecting the CPU itself, as well as the flash and RAM chips (the SSP has 16GB of flash and 2GB of RAM, as you might remember from the KS page tech specs). In the prototype photos you can see a small copper heatsink, which is only used for testing purposes. Below you can see the heatsink prototype we received and mounted on top of the CPU module. Total depth of module from back of front panel to top of heatsink is a little under 35mm. We've been testing the heatsink with a CPU stress utility on the serial console and it works well. We'll be testing this further over the coming weeks.

The only remaining port to be tested on the hardware is the USB device port. We'll be doing tests for that as we work on the software since its primary use is as a USB audio class device, so you can record into your computer. Our software outputs sound simultaneously to this port, besides outputting it to the onboard DAC.

Earlier today I was working on integrating the audio device with its 16 inputs and 8 outputs into our synthesis software. I'll be working on that over the next week, while also further updating the menu system to take advantage of the buttons and encoders on the SSP. The button layout of the SSP is a little different from the Percussa Engine so obviously we have to make a few adjustments there. Below you can see a few photos of the 2D network editor for the DSP modules.

That's it for now! We are excited about the SSP, it's coming together well, and we look forward to keeping you updated over the next weeks as we move forward.

Bert & Celine"