/docs/design_guide: added links to firmware build learning guides for SAMD21 & ESP8266. Changes were placed in the "Adding native modules" section, since that seemed to me the best place based on target audience.
Updated documentation for `delay()` which fixes#243.
Changes:
* New faster filter loop, by @ladyada. New filter coefficients as well.
* Turn on microphone clock when PDMIn object is created, and run it all the time, so the user code doesn't have to wait for microphone startup, which can be 10ms or even 100ms.
* Wait for microphone startup when PDMIn is first created, based on new optional parameter microphone_startup in seconds (takes a float).
* record() returns number of samples actually recorded, so you can see if it's not keeping up.
* Fix buffer overflow errors when buffer size was not a multiple of 16 or something like that.
* Tweak a few peripheral settings.
* Minimum sampling frequency is now 16kHZ or so, because 8kHz runs microphone at only 0.5MHz, which is too slow for many mics.
Note: I tried 128x oversampling instead of 64x, but the code cannot keep up at 24kHz or above sampling. 128x would reduce the high-frequency noise by 6db.
- Added D4 and moved associated SD_CS so that they are paired within list
- Added D7 and SD_CD which is the SD Card Detect pin
- Added D8 and GREEN_LED
- Added RED_LED associated with D13
- Added Setup information regarding arm complier packages
- README - Updated to reflect that feather_m0_adalogger microSD is supported
- Added D4 and moved associated SD_CS so that they are paired within list
- Added D7 and SD_CD which is the SD Card Detect pin
- Added D8 and GREEN_LED
- Added RED_LED associated with D13
- Added Setup information regarding arm complier packages
- Added D4 and moved associated SD_CS so that they are paired within list
- Added D7 and SD_CD which is the SD Card Detect pin
- Added D8 and GREEN_LED
- Added RED_LED associated with D13
Initially this library assumed the display is rotated by 90 degrees, so
the x and y were swapped. I'm now handling the display rotation in the
driver, with the hardware display settings, so the library should use
a sane order of x and y. This way it will work with any display
orientation.
Also, fixed pin mappings for rev B Metro M4:
swap PA12 and PA13 on SPI 2x3 header
swap A3 and A5
Comment out all frozen modules in CPX again to make room while waiting
for SPI flash.
