mirror of https://github.com/kidoman/embd
66 lines
1.5 KiB
Go
66 lines
1.5 KiB
Go
// Package mcp3008 allows interfacing with the mcp3008 8-channel, 10-bit ADC through SPI protocol.
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package mcp3008
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import (
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"github.com/golang/glog"
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"github.com/kidoman/embd"
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)
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// MCP3008 represents a mcp3008 8bit DAC.
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type MCP3008 struct {
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Mode, Bits byte
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Bus embd.SPIBus
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}
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//How many bits does the
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const (
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Bits10 = iota //10 bit MCP300** family
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Bits12 //12 bit MCP320** family
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)
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const (
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// SingleMode represents the single-ended mode for the mcp3008.
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SingleMode = 1
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// DifferenceMode represents the diffenrential mode for the mcp3008.
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DifferenceMode = 0
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)
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// New creates a representation of the mcp3008 convertor
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func New(mode, bits byte, bus embd.SPIBus) *MCP3008 {
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return &MCP3008{Mode: mode, Bus: bus}
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}
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const (
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startBit = 1
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)
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// AnalogValueAt returns the analog value at the given channel of the convertor.
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func (m *MCP3008) AnalogValueAt(chanNum int) (int, error) {
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var data [3]uint8
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switch m.Bits {
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case Bits10:
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data[0] = startBit
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data[1] = uint8(m.Mode)<<7 | uint8(chanNum)<<4
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data[2] = 0
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case Bits12:
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data[0] = (uint8(startBit) << 2) + (uint8(m.Mode) << 1) + (uint8(chanNum) >> 2)
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data[1] = uint8(chanNum) << 6
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data[2] = 0
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}
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glog.V(2).Infof("mcp3008: sendingdata buffer %v", data)
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if err := m.Bus.TransferAndReceiveData(data[:]); err != nil {
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return 0, err
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}
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switch m.Bits {
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case Bits10:
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return int(uint16(data[1]&0x03)<<8 | uint16(data[2])), nil
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case Bits12:
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return int(uint16(data[1]&0x0f)<<8 | uint16(data[2])), nil
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default:
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panic("mcp3008: unknown number of bits")
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}
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}
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