It had been a few weeks since I worked on my HDDSynth project for a number of reasons, so I needed to give myself a push to get over the initial inertia again.

One key reason for this is after I'd soldered in all of the components onto the MK1 prototype board, it didn't work

Well... let's be more precise. As a whole it didn't work, but most of the individual components did such as the sd card reader. That meant I'd at least created the PCB wiring correctly.

The key components that wouldn't pass my initial integration test was the audio amplifier. This takes an I2S digital audio signal from the Pi Pico and turns it into an amplified analogue signal for the speaker.

I had verified that the wiring was accurate to my designs then double and triple checked it. I tried another copies of the amp in case the initial one was bad and then moved onto trying other amp components. Nothing would work

In a leap of faith I decided to try hot wiring the audio amp to different output pins on the Pico

It worked

Just before I sent of the MK1 prototype PCB to be manufactured I switched out the original audio amp to another component which was cheaper and a better fit. However in my haste I hadn't fully validated that it worked on the pins I had chosen. As in theory, they should have worked fine.

So I still don't know why the originals pins had an issue, because as far as I understand the Pico they should be fine. Which meant to get my prototype board working I needed to attach some lovely bodge wires to use alternative pins for the audio.

Great - we have a working HDDSynth now, right?

Well... let's talk about that

My original prototype used a feed from the HDD LED line to detect HDD activity which worked very well. However after a suggestion from Ian Scott (of PicoGUS fame) I decided to try detecting HDD activity from reading the ISA bus.

I was attracted to this idea because it provides a plug and play solution. No additional wiring required. The power and data all comes from the ISA bus. Beautiful

However in practise although I could detect HDD activity from the ISA bus, I just wasn't getting the precise and accurate detection I'd hoped for. As I delved further into the realm of ISA signal reading I discovered that I may also need to read from the data lines to obtain the additional information required to make more accurate detections.

So I've decided to take a step back and return to the roots of this project. The MK2 prototype will still be an ISA card to obtain power and to allow for ease of installation, however it'll require an input from the HDD LED. The same approach used by the HDD Clicker.

This will enable me to create an initial MVP before then moving some something more sophisticated. 

Progress is rarely a straight line!