BMW Steering Wheel Buttons: The Universal Adapter

1// BMW Steering Wheel Buttons Universal Adapter
2// It decodes the original signals from the buttons to on/off
3// signals and steers a programable resistor for modern radio headers
4
5//Target: Pro Micro
6//
7#include <MCP4151.h>
8#include "IbusTrx.h"
9#define DEBUG
10
11#ifdef DEBUG
12  #define DEBUG_PRINTLN(x)  Serial.println (x)
13#else
14  #define DEBUG_PRINTLN(x)
15#endif
16
17#define CS     10
18#define MOSI   16
19#define MISO   14
20#define SCK    15
21
22const int POT_VOLMINUS = 255 - 0;
23const int POT_VOLPLUS = 255 - 1;
24const int POT_CHNMINUS = 255 - 2;
25const int POT_CHNPLUS = 255 - 3;
26const int POT_PHONE = 255 - 4;
27const int POT_SPMINUS = 255 - 6;
28const int POT_SPPLUS = 255 - 9;
29const int POT_IO = 255 - 13;
30const int POT_CC = 255 - 19;
31const int POT_RT = 255 - 26;
32const int POT_MAX = 256 - 38;
33
34
35const int INTERRUPTPIN = 2;
36const int PIN_CHNPLUS = 3;
37const int PIN_CHNMINUS = 4;
38const int PIN_VOLPLUS = 5;
39const int PIN_VOLMINUS = 6;
40const int PIN_PHONE = 7;
41
42const int PIN_CC = 8;
43const int PIN_IO = 9;
44const int PIN_SPPLUS = 20;
45const int PIN_SPMINUS = 19;
46const int PIN_RT = 18;
47
48IbusTrx ibusTrx;
49long m_EndTime;
50long m_Duration;
51int m_CCReceivedBuffer;
52volatile int m_CCReceived;
53volatile bool m_CCNewData;
54bool m_SuppressRT;
55bool m_WasCC;
56
57MCP4151 pot(CS, MOSI, MISO, SCK);
58
59void PinInterrupt(){
60  delayMicroseconds(234);
61  int bit = digitalRead(INTERRUPTPIN);
62  delayMicroseconds(234);
63  if(digitalRead(INTERRUPTPIN) == HIGH){
64    m_CCReceived = m_CCReceivedBuffer>>1;
65    m_CCReceivedBuffer = 0;
66    m_CCNewData = true;
67  }else{
68    m_CCReceivedBuffer = (m_CCReceivedBuffer<<1) + bit;
69  }
70}
71
72void setup() {
73
74#ifdef DEBUG
75  Serial.begin(9600);
76  delay(600);
77  Serial.println("Start");
78#endif
79  
80  m_Duration = 100;
81  m_EndTime = 0;
82  m_CCReceived = 0;
83  m_CCReceivedBuffer = 0;
84  m_CCNewData = false;
85  m_SuppressRT = false;
86  m_WasCC = false;
87  pinMode(PIN_CHNMINUS, OUTPUT);
88  pinMode(PIN_CHNPLUS, OUTPUT);
89  pinMode(PIN_VOLMINUS, OUTPUT);
90  pinMode(PIN_VOLPLUS, OUTPUT);
91  pinMode(PIN_PHONE, OUTPUT);
92  pinMode(PIN_RT, OUTPUT);
93  pinMode(PIN_CC, OUTPUT);
94  pinMode(PIN_IO, OUTPUT);
95  pinMode(PIN_SPMINUS, OUTPUT);
96  pinMode(PIN_SPPLUS, OUTPUT);
97  pinMode(INTERRUPTPIN, INPUT);
98  attachInterrupt(digitalPinToInterrupt(INTERRUPTPIN), PinInterrupt, RISING);
99  ibusTrx.begin(Serial1);
100  pot.writeValue(POT_MAX);
101}
102
103void loop() {
104  if(m_EndTime != 0 && millis() > m_EndTime){
105    digitalWrite(PIN_RT, LOW);
106    digitalWrite(PIN_VOLPLUS, LOW);
107    digitalWrite(PIN_VOLMINUS, LOW);
108    pot.writeValue(POT_MAX);
109    m_EndTime = 0;
110    DEBUG_PRINTLN("EndTime!");
111  } 
112
113  if (m_CCNewData){
114    m_CCNewData = false;
115    ccEvent();
116    m_CCReceived = 0;
117  }
118  
119  if (ibusTrx.available()) radioEvent();
120}
121
122void radioEvent(){
123  IbusMessage message = ibusTrx.readMessage();
124  if(message.source() != 80)return;
125
126  if(message.destination() == 176 || message.destination() == 208) m_SuppressRT = true;
127
128  if(message.destination() != 104 && message.destination() != 200) return;
129
130  if(message.b(0) == 1){
131    if(m_SuppressRT){
132      m_SuppressRT = false;
133      return;
134    }
135    m_EndTime = millis() + m_Duration;
136    pot.writeValue(POT_RT);
137    digitalWrite(PIN_RT, HIGH);
138    DEBUG_PRINTLN("RT");
139    return;
140  }
141
142  switch(message.b(0)<<8 | message.b(1)){
143    case  0x3211:
144      m_EndTime = millis() + m_Duration;
145      pot.writeValue(POT_VOLPLUS);
146      digitalWrite(PIN_VOLPLUS, HIGH);
147      DEBUG_PRINTLN("PIN_VOLPLUS_DOWN");
148    break;
149
150    case  0x3210:
151      m_EndTime = millis() + m_Duration;
152      pot.writeValue(POT_VOLMINUS);
153      digitalWrite(PIN_VOLMINUS, HIGH);
154      DEBUG_PRINTLN("PIN_VOLMINUS_DOWN");
155    break;
156
157    case  0x3B01:
158      pot.writeValue(POT_CHNPLUS);
159      digitalWrite(PIN_CHNPLUS, HIGH);
160      DEBUG_PRINTLN("PIN_CHNPLUS_DOWN");
161    break;
162
163    case  0x3B21:
164      pot.writeValue(POT_MAX);
165      digitalWrite(PIN_CHNPLUS, LOW);
166      DEBUG_PRINTLN("PIN_CHNPLUS_UP");
167    break;
168
169    case  0x3B08:
170      pot.writeValue(POT_CHNMINUS);
171      digitalWrite(PIN_CHNMINUS, HIGH);
172      DEBUG_PRINTLN("PIN_CHNMINUS_DOWN");
173    break;
174
175    case  0x3B28:
176      pot.writeValue(POT_MAX);
177      digitalWrite(PIN_CHNMINUS, LOW);
178      DEBUG_PRINTLN("PIN_CHNMINUS_UP");
179    break;
180
181    case  0x3B80:
182      pot.writeValue(POT_PHONE);
183      digitalWrite(PIN_PHONE, HIGH);
184      DEBUG_PRINTLN("PIN_PHONE_DOWN");
185    break;
186
187    case  0x3BA0:
188      pot.writeValue(POT_MAX);
189      digitalWrite(PIN_PHONE, LOW);
190      DEBUG_PRINTLN("PIN_PHONE_UP");
191    break;
192  }
193}
194
195void ccEvent(){
196  switch(m_CCReceived){
197    case 127:
198      if(m_WasCC) pot.writeValue(POT_MAX);
199      digitalWrite(PIN_CC, LOW);
200      digitalWrite(PIN_IO, LOW);
201      digitalWrite(PIN_SPPLUS, LOW);
202      digitalWrite(PIN_SPMINUS, LOW);
203      m_WasCC=false;
204    break;
205
206    case 55:
207      pot.writeValue(POT_CC);
208      digitalWrite(PIN_CC, HIGH);
209      m_WasCC=true;
210      DEBUG_PRINTLN("PIN_CC_DOWN");
211    break;
212
213    case 109:
214      pot.writeValue(POT_IO);
215      digitalWrite(PIN_IO, HIGH);
216      DEBUG_PRINTLN("PIN_IO_DOWN");
217      m_WasCC=true;
218    break;
219
220    case 91:
221      pot.writeValue(POT_SPPLUS);
222      digitalWrite(PIN_SPPLUS, HIGH);
223      DEBUG_PRINTLN("PIN_SPPLUS_DOWN");
224      m_WasCC=true;
225    break;
226
227    case 126:
228      pot.writeValue(POT_SPMINUS);
229      digitalWrite(PIN_SPMINUS, HIGH);
230      DEBUG_PRINTLN("PIN_SPMINUS_DOWN");
231      m_WasCC=true;
232    break;
233  }
234}