Part 1 is, implement
- M20: List SD card.
- M21: Initialize SD card (has to be done before listing).
- M22: Release SD card.
Do all this in one chunk, splitting this up wouldn't allow to test
the result.
For now this is just a nice demonstration on how to send bytes
over SPI. Add SD_CARD_SELECT_PIN to your configuration board
file manually to see data signals on MOSI dancing on the scope.
The TODO's about SS in arduino*.h were wrong, SS does have a
chip-specific special meaning (used in SPI multi-master or SPI
slave mode). Still, a #define MAX6675_SELECT_PIN is missing.
Squashed in this commit from the SPI development topic branch to
get this first step working:
Author: jbernardis <jeff.bernardis@gmail.com>
2015-02-04 22:35:07
mendel.c: disable SPI in power management only when not needed.
If we want to talk to a SD card connected to SPI, we need SPI
powered, of course.
From Traumflug: nice catch, Jeff!
This file was never in use and actually didn't even compile.
It didn't disturb so far because its whole content was wrapped
in #if 0. Recently it was fixed to at least compile, but code
quality was found to be poor enough to justify looking for
something written more carefully, which was found in FatFs
sample code.
Michael Moon
Markus Hitter