Status Reports

BARI BOX: This past week, I finalized the CAD for the BARI BOX and had it 3-D printed at TechSpark. The partially-assembled box is shown below. There were a few glitches in the manufacturing process, namely defacing of the surface finish and some poor tolerances in the mounting holes which will require drilling for further assembly, but overall this box is sufficient to serve as a mockup case for our design.

REV 2 MANUFACTURING: Components for BARI Rev 2 began to arrive this week, kick-starting my manufacturing of the new boards. My progress on the first Rev 2 board is shown below: I’ve assembled most of the pre-amplifier and analog effect stages, with the UI, ADC, and microprocessor to come next week as the necessary components arrive. The BM83 for this board was resoldered from a Rev 1 board due to the global chip shortage preventing us from obtaining a new device. The shielding case was dislodged during the resoldering process, and further testing is required to ensure the SoC remains functional.

PRE-AMP VERIFICATION: Finally, the new and more easily-solderable amplifiers arrived with Rev 2, and by retrofitting one of them onto a Rev 1 board, I was able to verify clean audio amplification on that Rev 1 board, as shown below:

Assuming that I receive the parts I need for next week, my goals are to finish the Rev 2 manufacturing quickly enough to help my teammates get the software of our device finished.

 

REV 2 FABRICATION: As we continue the process of bringing up the Rev 1 PCB and developing appropriate software, I am recording errata to inform the updates that will become the Rev 2 board. So far the only major errata is a mis-connection of one of the LCD pins which incorrectly sets the mode to serial instead of parallel. The target to finalize the Rev 2 design was 4/9/2021, but we pushed it back to the middle of the upcoming week to allow more time for verification on the Rev 1 hardware. Due to the overall excellent performance of the two Rev 1 boards, this should not significantly impact our schedule.

REV 1 BRINGUP: This week, I played a major role in supporting the bringup of the remaining peripherals on Rev 1. I helped Xingran to properly set up and communicate with the ADC, and I helped Sam properly set up and communicate with the LCD screen. At this point, essentially all of the peripherals are functional; the only somewhat undetermined element on the critical path is communication with / programming the BM83, but new programming hardware should allow us to resolve this shortly.

In the coming week, I will continue to assist with hardware bringup and simultaneously complete the mechanical design for the “BARI BOX”.

Working on the LCD with Sam:

REV 1 ASSEMBLY: This week most of my time was focused on Rev 1 hardware assembly in order to get working boards into the hands of my team members as quickly as possible. We decided that the new board (named “Alexey”) with the additional passive components we ordered from Digikey last week would go to Xingran while Sam would get the old board (named “Bernice”) which is still capable of running the UI modules.

By the end of the day on Thursday, I delivered both Alexey and Bernice, as well as a rotary encoder for Sam to test UI code and a power switch. A small amount of work still needs to be done on Alexey to fully implement the Analog Overdrive module, but since this is of secondary importance, we decided to put that off in favor of getting a prototype with a working ADC.

BARI BOX: Meanwhile, I continue to work on the mechanical design for BARI’s enclosure. At present, I can estimate that the cost for 3D printing + fasteners will be on the order of $50 (half of what we budgeted), though I am working on ways to make it lighter and thus cheaper.

I don’t have any good photos this week, so enjoy the remaining parts spread across the floor of my apartment:

And a close up of one of the unfinished boards:

And a suggestive, soft-focus close up for the fans out there 😉