ra8_io_sdhi_demo Directory Reference

Directory dependency graph for ra8_io_sdhi_demo:

Directories
	src

Detailed Description

Proves the ra8_io fabric's swappable-backend promise (epic #155, phase #156) on the native 4-bit SDHI controller (#123): the same VFS API that ra8_io_demo runs over a RAM disk and ra8_io_sd_demo runs over SD-over-SPI, now running over a micro-SD card reached through the dedicated SDHI host controller, by swapping only the block-device backend.

Everything above the block device is the identical fabric – bridge to ra8_fs, format and mount FAT16, register in the VFS, mkdir, then a write / read / byte-compare round-trip through the streaming file API. ra8_io_sd_demo binds the SD-over-SPI block device; this app binds ra8_io_blockdev_sdhi_init on top of the ra8_sdcard + ra8_sdhi HAL drivers, and the SD bring-up runs the full SD Physical Layer identification. Every return value is checked; the first failing step parks the CPU.

Warning: this app erases the card – it reformats FAT16. Insert a disposable microSD before booting.

Hardware

The eight SDHI bus pins are on port 4, pins 0..7, all routed to PSEL = k_ra8_psel_sdhi:

Port-4 pin	SDHI signal
P400	SD_CMD
P401	SD_CLK
P402	SD_DAT0
P403	SD_DAT1
P404	SD_DAT2
P405	SD_DAT3
P406	SD_WP
P407	SD_CD

Blocked on

A bench run with a real card. The native SDHI host controller is modelled off-target against a blank card image, so the fabric round-trip is automatable; what that cannot prove is the controller against real silicon and a real card's timing.