AXIOM Beta Development Progress Report

While it may seem like AXIOM development is currently on summer break - it is true that the planned crowd funding got delayed - there is a lot going on behind the scenes. So I thought I'd give a short update on what is currently cooking on the technical side.
We made an initial design for the AXIOM Beta power supply for testing, which basically consists of a two stage regulator, where the first stage is a switching regulator to accommodate a wide range of input voltages, and the second stage is a low noise LDO which ensures that we reach and keep the desired target voltages with as little loss and noise as possible.

preliminary power switcher board PCB (top / bottom)

In April we were offered some space on a larger PCB panel, so we got the chance to get some PCBs made without having to pay for them - Big thanks to Gabriel! We decided to get two of those preliminary switcher boards made for testing. When the PCBs were ready, we populated half a board and ran some basic tests, which were promising but not perfect for several reasons: For one, the chosen parts are not optimal and will probably get replaced in the next version. Second, the design still needs some minor improvements to make it easier for DIY assembly. We are currently preparing some kind of systematic testing to further improve the design.

dual micro SD PMOD module PCB (top / bottom)

While we waited for the power supply PCBs, we found some time to finish the first test version of the dual micro SD PMOD module planned for AXIOM Beta and also managed to add a FAN controller, again for testing. The PCBs have been ordered from OSHpark and should arrive in the next week, so that will probably become the next module to work on. In the gaps between, we did a lot of planning and component identification for the Beta board, which included going through a number of different crystals to satisfy the various clock requirements of the planned devices. This made me think about adding a dedicated clock chip to the mix to reduce the area and improve configurability. We found a number of interesting potential candidates and decided to do some testing on them, which resulted in two more side products in the form of PMOD clock module I and PMOD clock module II.

The layout is simple and kept generic, so it allows to try out different crystals and various chips from the same family without having to change the design. And of course, they can be reused for other projects as well. PCBs and components have been ordered and should arrive in the next few weeks. This reminds me that we are - mostly due to the delay with the crowd funding campaign - on low budget and every donation, regardless how small, is very welcome, because it will allow us to continue all those Beta preparations instead of sitting around and waiting for the campaign to finish. We will give some more updates when the PCBs arrive and we finished assembling and testing them.

PMOD clock module I PCB layout (top / bottom) / PMOD clock module II PCB layout (top / bottom)