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Working on programming AVR chips exposes a glaring omission in my first design of the SPI Relay: not allowing multiple devices make this task hard. I constantly have to unplug my SD card before, plug the AVR chip holder, then play a bit, then unplug the AVR holder, then replug the SD card... My prototype for a SPI relay design is built, but I haven't tested it yet. I need to adapt the code first, which is what I do here. When the prototype is tested, I'll update the SDC recipe with a new schema.
40 lines
1.2 KiB
Plaintext
40 lines
1.2 KiB
Plaintext
# Protocols
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Some subsystems (and in the case of KEY and EMIT, the core) re-
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quire drivers to implement certain words in a certain way. For
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example, the core requires drivers to implement (key) and (emit)
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or else it won't know how to provide a console.
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These protocols are described here.
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# TTY protocol
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(key) -- c Returns the next typed key on the console.
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If none, block until there is one.
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(emit) c -- Spit a character on the console.
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# PS/2 protocol
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This protocol enables communication with a device that spits
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PS/2 keycodes.
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(ps2kc) -- kc Returns the next typed PS/2 keycode from the
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console. Blocking.
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# SPI Relay protocol
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This protocol enables communication with a SPI relay. This
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protocol is designed to support devices with multiple endpoints.
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To that end, (spie) takes a device ID argument, with a meaning
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that is up to the device itself. To disable all devices, supply
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0 to (spie).
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We expect relay devices to support only one enabled device at
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once. Enabling a specific device is expected to disable the
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previously enabled one.
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(spie) n -- Enable SPI device
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(spix) n -- n Perform SPI exchange (push a number, get a
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number back)
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