This commit consolidates a number of check_esp_err functions that check
whether an ESP-IDF return code is OK and raises an exception if not. The
exception raised is an OSError with the error code as the first argument
(negative if it's ESP-IDF specific) and the ESP-IDF error string as the
second argument.
This commit also fixes esp32.Partition.set_boot to use check_esp_err, and
uses that function for a unit test.
Now that error string compression is supported it's more important to have
consistent error string formatting (eg all lowercase English words,
consistent contractions). This commit cleans up some of the strings to
make them more consistent.
This adds support for SD cards using the ESP32's built-in hardware SD/MMC
host controller, over either the SDIO bus or SPI. The class is available
as machine.SDCard and using it can be as simple as:
uos.mount(machine.SDCard(), '/sd')
Seon Rozenblum
Damien George
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Thorsten von Eicken
Damien George
Jim Mussared
Nicko van Someren