On Mon, 8 Jan 2018, Mark Webb-Johnson wrote:
Now finalising hardware with the china manufacturer. I think at this point, it is worth:
1. Use 1 line SD CARD (which frees up GPIOs SD_DATA1/SD_DATA2/SD_DATA3, but also avoids the conflict between GPIO12/SD_DATA2 and VDD_SDIO bootstrap pin).
I just go with the flow on this one.
2. Add some capacitors for power line smoothing, as per Espressif’s example in their test board.
Always a good idea.
3. Double-check power on SIMCOM module, to ensure it is as expected (following issues reported with low-amperage USB ports).
As I've been testing with release/v3.0 of esp-idf, I had to disable the brownout trap entirely. Even the lowest configured voltage would trap repeatedly. This is with a powered hub (SIIG brand, I think decent quality). Sometimes it seemed I could get by this by flashing again, but when it was happening it would repeat with every reset.
4. Change to use Analog Lamb WROOM-32 module and their 16MB flash + 4MB ram.
Would it be feasible to add our own SPIRAM chip to use with the WROOM module? -- Steve