With the adoption of USB as primary interconnect format for our boards and the use of dual-side connectors for RJ45 and USB connectors, we’ve managed to get rid of the connector board. As a result, the two dualport DB25 connectors will be mounted directly on the audio ADC and DAC boards, which should further simplify our cabling work, while improving sound quality (less hops).
We’ve also decided to merge the keypad board and transport board into a single board, which we will continue to refer as the keypad board. The block diagram above now clearly outlines our USB bus architecture, which I tend to like quite a bit. With this approach, we should be able to quickly prototype the backplane, keypad board, and CV board independently of each other.
One thing we were not sure about is whether a microcontroller should be used on the CV board, or whether we should simply use a pair of of AS1113 LED drivers. We finally decided to go for the former, thereby sticking to the approach consisting in using the USB bus for all controls and indicators. Then, we asked ourselves whether this microcontroller should be connected to the backplane directly, or through one of the two USB hubs located on the keypad board. We decided to go for the former in order to reduce the number of cables coming out of the backplane.