The parts have arrived!

Yesterday morning, I soldered the pins to the components I'm going to use. I also soldered a PML capacitor between two pins to use for coupling. In my haste, I soldered the PAM module upside down. :D Doesn't matter much, except that the silkscreen and components are now on the bottom. Stupid me. Not having a workstation to solder at makes it a bit time-consuming, as I have to set everything up, solder, clean up, remove all the tools, and store them. The project and all my tools live in boxes and they have to go back into the closet before I go to work.

I've connected everything, I've not used a separate LDO for audio, so there might be some noise. I have to double check all connections before powering it up.

This morning I did some programming. I've added LUTs for the DTMF tones but I also need to add a LUT for the dialing tone. I've added a function that plays DTMF tones.

The dialing tone will be played when waiting for input. There is a small delay needed to maintain the sample rate, this might cause issues with user input. I might need to add the check for the key pressed signal inside the loop which sends the values to the DAC.
Perhaps an ISR might be the way to go for the key pressed signal, enabled only when the handset is off. Then I wouldn't need to worry about it as the ISR would switch states to the key_pressed state.

Looking at everything it has become clear that for the final version I need a custom mainboard. Gluing all these modules inside would probably be a disaster if I want to use it daily. It's something I'll worry about when the prototype is completed.