Hi,
First off, I'm sorry if I used the wrong subsection, but this forum has so many of them and several applies.
I'm creating a board for interfacing with a sensor through CAN bus. The sensor (ADIS16488A) uses SPI and has a lot of things that can be configured. On the CAN bus side there will be a logger (HBM Quantum MX) that will be recording CAN messages of choice. The board I'm making will be reading sensor data through SPI and sending it to the logger through CAN bus. If done correctly, it will be plug'n'play.
This project probably doesn't have any appeal outside my very specific use case, but I'm making it open source so I can use it for self promotion. Everything I do at work is under NDAs (or worse) so I need something to show in job interviews.
My discipline is programming, not electronics, so I need some help with the board.
I have tried to split the schematic up in modules to make it easier to follow. The full schematic is attached as a pdf.
I tried to export a BOM from kiCad, but it didn't do a good job.
The first module is the MCU:
The MCU is a STM32F042F6P6.
Here the bypassing is well covered by the datasheet, so it should be OK. I may have simplified the VDDA slightly since I won't be using the ADC.
The crystal was a bit harder since the caps are dependent on the crystal. I chose a TXC 7A-8.000MAAE-T and it says 12pF in the description, so I chose generic 1206 12pF ceramic caps. It was not clear to me if any resistors are needed.
See PDF for SWD connector, but that part is tested in a earlier design and should be correct.
CAN tranceiver:
The CAN transmitter should be easy I hope. The datasheet didn't specify the bypass caps, so I copied two from the MCU.
I hope someone can confirm my pin choice on the DB9 connector. Which pins to use for power wasn't very clear in the standard.
Power supply:
Power supply design is way beyond my skill. I ended up using the Texas Instrument Webench Power Designer and just copying the reference design. I chose one with a huge voltage range just to eliminate the need for any over-voltage protection. It will normally be supplied with 6V and use 250mA@3.3V.
C9: C2012X5R1V106K085AC
C10: C3216X5R1E476M160AC, this is discontinued, so I have to find a replacement.
Any help is appreciated. Constructive criticism is also appreciated, but keep in mind that I'm not a EE and don't intend to become one. I just need a platform for my software.
I will start laying out the board tomorrow, hopefully I won't need to make too many revisions.