From 9c1817a8194a05d9db64b4fd24fe04b23d7da40d Mon Sep 17 00:00:00 2001
From: analogic <info@analogic.cz>
Date: Sat, 27 May 2017 14:57:32 +0200
Subject: [PATCH] Adding MCP3208 convertor

Copy of mcp3008 with necessary changes derived from https://github.com/kidoman/embd/pull/47 to make MCP3208 work. Creating new driver instead of changing API of different model (like pull 47) seems to be better choice.
---
 convertors/mcp3208/mcp3208.go | 45 +++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 convertors/mcp3208/mcp3208.go

diff --git a/convertors/mcp3208/mcp3208.go b/convertors/mcp3208/mcp3208.go
new file mode 100644
index 0000000..3347392
--- /dev/null
+++ b/convertors/mcp3208/mcp3208.go
@@ -0,0 +1,45 @@
+// Package mcp3208 allows interfacing with the mcp3208 8-channel, 12-bit ADC through SPI protocol.
+package mcp3208
+
+import (
+	"github.com/golang/glog"
+	"github.com/kidoman/embd"
+)
+
+// MCP3208 represents a mcp3208 8bit DAC.
+type MCP3208 struct {
+	Mode byte
+	Bus  embd.SPIBus
+}
+
+const (
+	// SingleMode represents the single-ended mode for the mcp3208.
+	SingleMode = 1
+
+	// DifferenceMode represents the diffenrential mode for the mcp3208.
+	DifferenceMode = 0
+)
+
+// New creates a representation of the mcp3208 convertor
+func New(mode byte, bus embd.SPIBus) *MCP3208 {
+	return &MCP3208{mode, bus}
+}
+
+const (
+	startBit = 1
+)
+
+// AnalogValueAt returns the analog value at the given channel of the convertor.
+func (m *MCP3208) AnalogValueAt(chanNum int) (int, error) {
+	var data [3]uint8
+	data[0] = (uint8(startBit) << 2) + (uint8(m.Mode) << 1) + (uint8(chanNum) >> 2)
+	data[1] = uint8(chanNum) << 6
+	data[2] = 0
+
+	glog.V(2).Infof("mcp3208: sendingdata buffer %v", data)
+	if err := m.Bus.TransferAndReceiveData(data[:]); err != nil {
+		return 0, err
+	}
+
+	return int(uint16(data[1] & 0x0f) << 8 | uint16(data[2])), nil
+}