• The project has officially started.

    Josh Lloyd03/07/2019 at 06:17 0 comments

    Initial design has begun, I would usually do my design in KiCad but I thought I'd like to give EasyEDA a try. I really want to try out the integration between EasyEDA/LCSC/JLCPCB because I've not used any of these services previously, and having a Cloud based EDA seems like a good idea for collab/public space projects.

    Here are the two sheets for my current design. I may reduce this to one sheet in the future, depending on how much real estate I use. But I like to have some space to do lazy drag-selection when designing.

    I want to be able to use the Top Level Sequencer (State Machine) on the SX1276 (RFM95), as well as the FSK and OOK modes. Some of the features I want such as Preamble/RSSI Detect require DIO3 or DIO4 so I at least need more DIO pins than the usual LoRaWAN stack for example. (DIO0-DIO2)

    I'm torn between mapping all of the DIO pins to the ESP32 (The Input only pins from 34 to 39 are tempting), or just using some diodes here. I could also do a Wire OR, that can't be too bad right? I really need to think about the DIO more before I finalize that part of the design. Page 1 shows a tiny Diode array I found on Digikey (1.6mm square) but this could be precious real-estate later, they are also $0.50 each.

    Another thing I do not have is a header to break all the pins out. I want something low profile (mezzanine connector?), and I'm also considering a castellated PCB. Still things to consider here.