31 lines
1.4 KiB
Go
31 lines
1.4 KiB
Go
// Copyright 2016 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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// Package chip contains header definitions for NextThing Co's C.H.I.P. board.
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//
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// CHIP uses the Allwinner R8 processor and thus the allwinner host package is
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// automatically imported.
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//
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// This package exports the U13 header, which is opposite the power LED, and
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// U14, which is right next to the power LED. Most of the pins are usable as
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// GPIO and are directly to the processor. These can use memory-mapped GPIO,
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// which is very fast. The XIO-P0 through XIO-P7 pins are attached to a pcf8574
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// I²C expander which has the result that all accesses to these pins have to go
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// through the kernel and the I²C bus protocol, i.e., they're slow.
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//
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// GPIO edge detection (using interrupts) is only supported on a few of the
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// processor's pins: AP-EINT1, AP-EINT3, CSIPCK, and CSICK. Edge detection is
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// also supported on the XIO pins, but this feature is rather limited due to
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// the device and the driver (for example, the driver interrupts on all edges).
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//
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// References
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//
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// http://www.chip-community.org/index.php/Hardware_Information
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//
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// http://docs.getchip.com/chip.html#chip-hardware
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//
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// A graphical view of the board headers is available at:
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// http://docs.getchip.com/chip.html#pin-headers
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package chip
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