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Preparation finished + 3D printed enclosure delays

A project log for BitMasher

Portable lo-fi music sequencer

Michele PerlaMichele Perla 12/22/2014 at 16:510 Comments

Hey there,

A few updates on the status of the project:

I finished preparation phase for the project, the schematic and layout have been polished and reviewed, and the PCBs are already shipping from Shenzen, Public Rep. of China; Smart Prototyping has been my choice because they are the only cheap manufacturers that offer 24 H turnaround time and overtime for shipping on weekends, I should receive the boards in a couple days.

In the meantime, I received all the components (ICs, resistors, capacitors, USB micro connectors etc) that will populate the boards as soon as I come back from my holidays (December 28th). I also received the 3V Pro Trinket and a 3V-to-5V logic converter to hook up the Trinket Pro with all the mandatory components at the same time, that is OLED, ROM, tactile switch and Trellis (it needs the 3-to-5V conversion). I ended up only putting direct connection to the two PWM pins on the PCB, I didn't have the time to properly test a filter+headphone amp, but I at least put an headphone jack connector hole on the enclosure; if I don't have the time to do a proper headphone amp (single supply I hate you) I'll at least try to filter the PWM a bit for line-output

My plans for this week are to start (FINALLY!) putting together all the pieces of the somewhat huge puzzle that is this project; I'm actually testing on breadboard all the hardware I currently have using the connections as reported on the schematic, setting Chip Selects on Analog Pins, modding the SPI devices libraries to handle that, simulating interrupt and command pins using jumpers to implement low battery conditions-power on-power off sequencing; then I will dig my old code and get the synth and the sequencer up and running; I'll first fly low and test 2 concurrent sample tracks and 2 synth tracks, while also converting everything to fixed point arithmetic (my old code is using floating point, not fast at all). I also have to organize a memory map to organize storage of Songs, Patterns, Tracks, and Samples; I may want to implement a fixed addresses memory section to hold the former three, while the samples may have variable (but limited maximum) length, the idea for samples conversion is that the 8-bit audio will be preceded by a header storing a short name and a length value, and there will be a list that contains the addresses of the currently stored samples. For test purposes, I will hold test samples in program memory and write them to ROM, then access the ROM for playback; when I'll have the Serial conversion working I'll store the samples directly in ROM, but that will come later in development as I have to implement a little Java application to do so (get 8 bit 16KHz WAV file, start connection with BitMasher, transfer data ) which will probably only have a "dump everything" option to copy the ROM content and erase it.

Regarding the enclosure: I managed to cut a small timeframe for it and I finished it yesterday evening, so I had to send it for print outside Rome; luckily this store is only closed from December 25th to 28th, so they'll probably print everything out today and send it with "really-urgent-delivery" tomorrow. Cross fingers!

Here's the final enclosure (I opted for black everything, grey sides):

This enclosure here is derived from the Trellis Box and it's the first 3D model I make in a lot of years (10+) and it's the very first 3D model I print, so I really hope that I didn't mess with support frames heights and other stuff :S

Now, it's time for me to go home as my work shift is ending in a few minutes and I gotta take a train. I'll try to post more details this night or tomorrow morning.

As always, Cheers.

Mick

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