Rev Author Line No. Line
1580 kakl 1 /************ SMB driver ************/
2  
3 #define SA 0x00 // Slave Address (0 for single slave / 0x5A<<1 default)
4 #define RAM_Access 0x00 // RAM access command
5 #define RAM_Tobj1 0x07 // To1 address in the RAM
6 #define RAM_Tamb 0x06 // Ta address in the RAM
7  
8  
9 // High and Low level of clock
10 #define HIGHLEV 40 // max. 50us
11 #define LOWLEV 100 // max. 30ms
12 #define TBUF 20
13  
14 // SMBus control signals
1585 kakl 15 #define SCL PIN_B4
1580 kakl 16 #define SDA PIN_B1
17  
18 #define mSDA_HIGH() output_float(SDA); // SDA float
19 #define mSDA_LOW() output_low(SDA); // SDA low
20 #define mSCL_HIGH() output_float(SCL); // SCL float
21 #define mSCL_LOW() output_low(SCL); // SCL low
22  
23 #define ACK 0
24 #define NACK 1
25  
26 //**********************************************************************************************
27 // START CONDITION ON SMBus
28 //**********************************************************************************************
29 //Name: START_bit
30 //Function: Generate START condition on SMBus
31 //Parameters: No
32 //Return: No
33 //Comments: Refer to "System Managment BUS(SMBus) specification Version 2.0"
34 // or AN"SMBus communication with MLX90614" on the website www.melexis.com
35 //**********************************************************************************************
36 void SMB_START_bit(void)
37 {
38 // disable_interrupts(GLOBAL);
39 mSDA_HIGH(); // Set SDA line
40 delay_us( TBUF ); // Wait a few microseconds
41 mSCL_HIGH(); // Set SCL line
42 delay_us( TBUF ); // Generate bus free time between Stop
43 // and Start condition (Tbuf=4.7us min)
44 mSDA_LOW(); // Clear SDA line
45 delay_us( TBUF ); // Hold time after (Repeated) Start Condition.
46 // After this period, the first clock is generated.
47 // (Thd:sta=4.0us min)
48 mSCL_LOW(); // Clear SCL line
49 // enable_interrupts(GLOBAL);
50 delay_us( TBUF ); // Wait a few microseconds
51 }
52  
53 //*********************************************************************************************
54 // STOP CONDITION ON SMBus
55 //*********************************************************************************************
56 //Name: STOPbit
57 //Function: Generate STOP condition on SMBus
58 //Parameters: No
59 //Return: No
60 //Comments: Refer to "System Managment BUS(SMBus) specification Version 2.0"
61 // or AN"SMBus communication with MLX90614" on the website www.melexis.com
62 //*********************************************************************************************
63 void SMB_STOP_bit(void)
64 {
65 // disable_interrupts(GLOBAL);
66 mSDA_HIGH();
67 mSCL_LOW(); // Clear SCL line
68 delay_us( TBUF ); // Wait a few microseconds
69 mSDA_LOW(); // Clear SDA line
70 delay_us( TBUF ); // Wait a few microseconds
71 mSCL_HIGH(); // Set SCL line
72 delay_us( TBUF ); // Stop condition setup time(Tsu:sto=4.0us min)
73 mSDA_HIGH(); // Set SDA line
74 // enable_interrupts(GLOBAL);
75 }
76  
77  
78 void SMB_send_bit(unsigned char bit_out)
79 {
80 // disable_interrupts(GLOBAL);
81 if(bit_out==0) {mSDA_LOW();}
82 else {mSDA_HIGH();}
83 delay_us(3);
84 mSCL_HIGH(); // Set SCL line
85 delay_us( HIGHLEV ); // High Level of Clock Pulse
86 mSCL_LOW(); // Clear SCL line
87  
88 //!!! toggle_dome();
89 delay_us(1);
90  
91 delay_us( LOWLEV ); // Low Level of Clock Pulse
92 // mSDA_HIGH(); // Master release SDA line ,
93 // enable_interrupts(GLOBAL);
94  
95 //!!! toggle_dome();
96 delay_us(1);
97 return;
98 }
99  
100 unsigned char SMB_Receive_bit(void)
101 {
102 unsigned char Ack_bit;
103  
104 // disable_interrupts(GLOBAL);
105 mSDA_HIGH(); //_SDA_IO=1; // SDA-input
106 mSCL_HIGH(); // Set SCL line
107 delay_us( HIGHLEV ); // High Level of Clock Pulse
108 if(input(SDA)) Ack_bit=1; // \ Read acknowledgment bit, save it in Ack_bit
109 else Ack_bit=0; // /
110 mSCL_LOW(); // Clear SCL line
111  
112 //!!! toggle_dome();
113 delay_us(1);
114  
115 delay_us( LOWLEV ); // Low Level of Clock Pulse
116 // enable_interrupts(GLOBAL);
117  
118 //!!! toggle_dome();
119 delay_us(1);
120  
121 return Ack_bit;
122 }
123  
124  
125 //*********************************************************************************************
126 // TRANSMIT DATA ON SMBus
127 //*********************************************************************************************
128 //Name: TX_byte
129 //Function: Send a byte on SMBus
130 //Parameters: TX_buffer ( the byte which will be send on the SMBus )
131 //Return: Ack_bit ( acknowledgment bit )
132 //Comments: Sends MSbit first
133 //*********************************************************************************************
134 unsigned char SMB_TX_byte(unsigned char Tx_buffer)
135 {
136 unsigned char Bit_counter;
137 unsigned char Ack_bit;
138 unsigned char bit_out;
139  
140 for(Bit_counter=8; Bit_counter; Bit_counter--)
141 {
142 if(Tx_buffer&0x80) bit_out=1; // If the current bit of Tx_buffer is 1 set bit_out
143 else bit_out=0; // else clear bit_out
144  
145 SMB_send_bit(bit_out); // Send the current bit on SDA
146 Tx_buffer<<=1; // Get next bit for checking
147 }
148  
149 Ack_bit=SMB_Receive_bit(); // Get acknowledgment bit
150  
151 return Ack_bit;
152 }
153  
154 //*********************************************************************************************
155 // RECEIVE DATA ON SMBus
156 //*********************************************************************************************
157 //Name: RX_byte
158 //Function: Receive a byte on SMBus
159 //Parameters: ack_nack (ackowlegment bit)
160 //Return: RX_buffer(Received byte)
161 //Comments: MSbit is received first
162 //*********************************************************************************************
163 unsigned char SMB_RX_byte(unsigned char ack_nack)
164 {
165 unsigned char RX_buffer;
166 unsigned char Bit_Counter;
167  
168 for(Bit_Counter=8; Bit_Counter; Bit_Counter--)
169 {
170 if(SMB_Receive_bit()) // Get a bit from the SDA line
171 {
172 RX_buffer <<= 1; // If the bit is HIGH save 1 in RX_buffer
173 RX_buffer |=0b00000001;
174 }
175 else
176 {
177 RX_buffer <<= 1; // If the bit is LOW save 0 in RX_buffer
178 RX_buffer &=0b11111110;
179 }
180 }
181  
182 SMB_send_bit(ack_nack); // Sends acknowledgment bit
183  
184 return RX_buffer;
185 }
186  
187  
188 unsigned char PEC_calculation(unsigned char pec[]) // CRC calculation
189 {
190 unsigned char crc[6];
191 unsigned char BitPosition=47;
192 unsigned char shift;
193 unsigned char i;
194 unsigned char j;
195 unsigned char temp;
196  
197 do
198 {
199 crc[5]=0; /* Load CRC value 0x000000000107 */
200 crc[4]=0;
201 crc[3]=0;
202 crc[2]=0;
203 crc[1]=0x01;
204 crc[0]=0x07;
205 BitPosition=47; /* Set maximum bit position at 47 */
206 shift=0;
207  
208 //Find first 1 in the transmited message
209 i=5; /* Set highest index */
210 j=0;
211 while((pec[i]&(0x80>>j))==0 && i>0)
212 {
213 BitPosition--;
214 if(j<7)
215 {
216 j++;
217 }
218 else
219 {
220 j=0x00;
221 i--;
222 }
223 //!!! toggle_dome();
224 delay_us(1);
225  
226 }
227  
228 shift=BitPosition-8; /*Get shift value for crc value*/
229  
230  
231 //Shift crc value
232 while(shift)
233 {
234 for(i=5; i<0xFF; i--)
235 {
236 if((crc[i-1]&0x80) && (i>0))
237 {
238 temp=1;
239 }
240 else
241 {
242 temp=0;
243 }
244 crc[i]<<=1;
245 crc[i]+=temp;
246 }
247 shift--;
248 //!!! toggle_dome();
249 delay_us(1);
250  
251 }
252  
253 //Exclusive OR between pec and crc
254 for(i=0; i<=5; i++)
255 {
256 pec[i] ^=crc[i];
257 }
258 } while(BitPosition>8);
259  
260 return pec[0];
261 }