[Ovmsdev] SD CARD vs 16MB flash

Stephen Casner casner at acm.org
Tue Jan 9 00:57:01 HKT 2018

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

                                                        -- Steve

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