35 lines
1.6 KiB
TypeScript
35 lines
1.6 KiB
TypeScript
/**
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* Generic SPI bus interface, board-agnostic.
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*
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* Every simulator (AVR, RP2040, ESP32 Xtensa/RISC-V, RiscV bare-metal,
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* Pi-Pico-W, …) exposes a `.spi` member matching this shape so SPI-driven
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* components — ILI9341 displays, custom chips, SD cards, etc. — can hook
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* the bus without knowing which board they're attached to.
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*
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* The contract follows the AVRSimulator's existing shape (the original
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* implementation): the consumer assigns its handler to `onByte`, which
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* receives one MOSI byte per SPI clock cycle. If the consumer is a slave
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* that wants to drive the master's MISO line for that cycle, it calls
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* `completeTransfer(miso)`. For boards where MISO is driven externally
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* (ESP32 — the QEMU worker handles the response via _spi_response),
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* `completeTransfer` is a no-op.
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*
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* Each simulator's `.spi` is a SINGLE-LISTENER channel: assigning to
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* `onByte` overwrites any previous handler. Components that wrap an
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* existing handler must save the old one and chain it in their own
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* implementation (the standard pattern; see ili9341Simulation in
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* ComplexParts.ts).
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*/
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export interface SpiBusLike {
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/** Settable per-cycle byte handler. Null when no consumer is attached. */
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onByte: ((mosi: number) => void) | null;
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/**
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* Tell the master what to place on MISO for the current cycle.
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* Optional — boards where MISO is owned by the emulator (ESP32) treat
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* this as a no-op. Hardware-faithful boards (AVR, RP2040) must call
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* this before the next byte arrives or the master will read 0.
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*/
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completeTransfer?(miso: number): void;
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}
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