1// Copyright 2016 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Package spi allows users to read from and write to an SPI device. 6// 7// Deprecated 8// 9// This package is not maintained anymore. An actively supported cross-platform 10// alternative is https://periph.io/. 11package spi // import "golang.org/x/exp/io/spi" 12 13import ( 14 "time" 15 16 "golang.org/x/exp/io/spi/driver" 17) 18 19// Mode represents the SPI mode number where clock parity (CPOL) 20// is the high order and clock edge (CPHA) is the low order bit. 21type Mode int 22 23const ( 24 Mode0 = Mode(0) 25 Mode1 = Mode(1) 26 Mode2 = Mode(2) 27 Mode3 = Mode(3) 28) 29 30// Order is the bit justification to be used while transfering 31// words to the SPI device. MSB-first encoding is more popular 32// than LSB-first. 33type Order int 34 35const ( 36 MSBFirst = Order(0) 37 LSBFirst = Order(1) 38) 39 40type Device struct { 41 conn driver.Conn 42} 43 44// SetMode sets the SPI mode. SPI mode is a combination of polarity and phases. 45// CPOL is the high order bit, CPHA is the low order. Pre-computed mode 46// values are Mode0, Mode1, Mode2 and Mode3. 47// The value can be changed by SPI device's driver. 48func (d *Device) SetMode(mode Mode) error { 49 return d.conn.Configure(driver.Mode, int(mode)) 50} 51 52// SetMaxSpeed sets the maximum clock speed in Hz. 53// The value can be overriden by SPI device's driver. 54func (d *Device) SetMaxSpeed(speed int) error { 55 return d.conn.Configure(driver.MaxSpeed, speed) 56} 57 58// SetBitsPerWord sets how many bits it takes to represent a word, e.g. 8 represents 8-bit words. 59// The default is 8 bits per word. 60func (d *Device) SetBitsPerWord(bits int) error { 61 return d.conn.Configure(driver.Bits, bits) 62} 63 64// SetBitOrder sets the bit justification used to transfer SPI words. 65// Valid values are MSBFirst and LSBFirst. 66func (d *Device) SetBitOrder(o Order) error { 67 return d.conn.Configure(driver.Order, int(o)) 68} 69 70// SetDelay sets the amount of pause will be added after each frame write. 71func (d *Device) SetDelay(t time.Duration) error { 72 return d.conn.Configure(driver.Delay, int(t.Nanoseconds()/1000)) 73} 74 75// SetCSChange sets whether to leave the chipselect enabled after a Tx. 76func (d *Device) SetCSChange(leaveEnabled bool) error { 77 v := 0 78 if leaveEnabled { 79 v = 1 80 } 81 return d.conn.Configure(driver.CSChange, v) 82} 83 84// Tx performs a duplex transmission to write w to the SPI device 85// and read len(r) bytes to r. 86// User should not mutate the w and r until this call returns. 87func (d *Device) Tx(w, r []byte) error { 88 // TODO(jbd): Allow nil w. 89 return d.conn.Tx(w, r) 90} 91 92// Open opens a device with the specified bus and chip select 93// by using the given driver. If a nil driver is provided, 94// the default driver (devfs) is used. 95 96func Open(o driver.Opener) (*Device, error) { 97 conn, err := o.Open() 98 if err != nil { 99 return nil, err 100 } 101 return &Device{conn: conn}, nil 102} 103 104// Close closes the SPI device and releases the related resources. 105func (d *Device) Close() error { 106 return d.conn.Close() 107} 108