esp-idf/components/driver/sdio_slave/README.md

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# SDIO workflow
This README is a supplement to the comments in the SDIO slave driver. For more details, see `sdio_slave.c`.
The diagram are described in mermaid format. You can view the diagrams on Github or with any mermaid renders.
## Sending direction
```mermaid
sequenceDiagram
actor task
participant ISR
participant HW
Note right of HW: always: rx_done.raw = 1, rx_eof.ena= 1
task-->>ISR: Prepare transfers
task->>HW: rx_done.ena=1
activate HW
%% First ISR triggering transfer
HW->>ISR: trigger
activate ISR
ISR->>HW: rx_done.ena=0
deactivate HW
loop every finished descriptor
note over task, HW: skipped, see below
end
opt HW idle && new transfer prepared
ISR->>HW: Load transfer
end
deactivate ISR
activate HW
HW->>HW: Host doing RX transfer
deactivate HW
HW->>HW: rx_eof.raw=1
activate HW
%% Second ISR recycling transfer
HW->>ISR: trigger
activate ISR
ISR-->>HW: rx_done.ena=0
loop every finished descriptor
ISR->>HW: rx_eof.raw=0
deactivate HW
ISR-->>task: inform
end
opt HW idle && new transfer prepared
note over ISR, HW: Load next transfer if there is...
end
deactivate ISR
```