SD SPI mode driver
This MR adds functionality to support SD cards connected via SPI interface.
Additionally, two bugs are fixed:
- Definition of `SPI_TRANS_MODE_DIOQIO_ADDR` in spi_master driver
- SD card probing frequency was 4000kHz instead of 400kHz as required by the standard
See merge request !727
NVS is used to store PHY calibration data, WiFi configuration, and BT
configuration. Previously BT examples did not call nvs_flash_init,
relying on the fact that it is called during PHY init. However PHY init
did not handle possible NVS initialization errors.
This change moves PHY init procedure into the application, and adds
diagnostic messages to BT config management routines if NVS is not
initialized.
* Use "example" in all example function & variable names,
ie use i2c_example_xxx instead of i2c_xxx for example functions.
Closes#198https://github.com/espressif/esp-idf/issues/198
* Mark example functions, etc. static
* Replace uses of "test" & "demo" with "example"
* Split the UART example into two
* Rename "main" example files to end with "_main.c" for disambiguation
nvs_flash_init may return an error code in some cases, and applications
should check this error code (or at least assert on it being ESP_OK, to
make potential issues more immediately obvious).
This change modifies all the examples which use NVS to check the error
code. Most examples get a simple ESP_ERROR_CHECK assert, while NVS
examples, OTA example, and NVS unit tests get a more verbose check which
may be used in real applications.
* New "espefuse.py set_flash_voltage" command to easily set a fix
VDD_SDIO regulator voltage (1.8V, 3.3V or disabled).
* Fixes bugs when flashing files with non-4-byte aligned lengths
(doesn't effect esp-idf image files)
* README improvements
