Hello,
The Raspberry Pi SPI bus on the P1 GPIO header is already working, both
through polling and interrupts on the bus FIFOS, and has been tested
with a microchip 23k256 SRAM device.
The bus code can be found in:
https://github.com/asuol/rtems/blob/GPIO_API/c/src/lib/libbsp/arm/raspberrypi/i2c/spi.c
The 23k256 SRAM minimal device driver (based in the
libchip/i2c/spi-memdrv driver) used to test the bus can be found in:
https://github.com/asuol/rtems/blob/GPIO_API/c/src/libchip/i2c/23k256.c
The application that tests the device can be found in:
https://github.com/asuol/rtems/blob/GPIO_API/testsuites/samples/SPI_23k256_TEST/init.c
Alan, from what I have seen of your adafruit FRAM device datasheet I
recon that it should also work with my 23k256 driver if you comment out
lines 65 through 106, as it just sets the device in sequential mode
which your device already uses.
The current pending issues with the SPI implementation are:
- Currently the bus is registered in the system through a function
called on an application. Should it stay this way or should the bus be
registered in the system in the predriver-hook during the BSP startup?
- It can currently work either in polling or interrupt mode, as well as
in either 3-wire mode (miso, mosi, and sclk) or in 2-wire mode
(bi-directional mode by turning the bus around in the mosi data line,
although this stills needs to be tested with another device). These
configuration options are currently made staticaly during the SPI bus
initialization, but they should be made elsewhere by the user. Should
these options be passed to the bus register function or through define
constants?
Thanks,
André Marques.
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