Rev 3074 Rev 3375
1 /* 1 /*
2 MPL115A1 SDN - +3.3V (always power on) 2 MPL115A1 SDN - +3.3V (always power on)
3 MPL115A1 #CS - PIN_C2 3 MPL115A1 #CS - PIN_C2
4 MPL115A1 DOUT - PIN_C4 4 MPL115A1 DOUT - PIN_C4
5 MPL115A1 DIN - PIN_C5 5 MPL115A1 DIN - PIN_C5
6 MPL115A1 SCLK - PIN_C3 6 MPL115A1 SCLK - PIN_C3
7 MPL115A1 GND - GND 7 MPL115A1 GND - GND
8 MPL115A1 VDD - +3.3V 8 MPL115A1 VDD - +3.3V
9 */ 9 */
10   10  
11   11  
12 // SPI mode definitions. 12 // SPI mode definitions.
13 #define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H) 13 #define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
14 #define SPI_MODE_1 (SPI_L_TO_H) 14 #define SPI_MODE_1 (SPI_L_TO_H)
15 #define SPI_MODE_2 (SPI_H_TO_L) 15 #define SPI_MODE_2 (SPI_H_TO_L)
16 #define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H) 16 #define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
17   17  
18 float a0; // correctiaon coefficients 18 float a0; // correctiaon coefficients
19 float b1; 19 float b1;
20 float b2; 20 float b2;
21 float c12; 21 float c12;
22   22  
23   23  
24 void MPL_init() 24 void MPL_init()
25 { 25 {
26 unsigned int8 a0_MSB, a0_LSB; 26 unsigned int8 a0_MSB, a0_LSB;
27 unsigned int8 b1_MSB, b1_LSB; 27 unsigned int8 b1_MSB, b1_LSB;
28 unsigned int8 b2_MSB, b2_LSB; 28 unsigned int8 b2_MSB, b2_LSB;
29 unsigned int8 c12_MSB, c12_LSB; 29 unsigned int8 c12_MSB, c12_LSB;
30   30  
31 output_low(CSN_SPI); 31 output_low(CSN_SPI);
32   32  
33 spi_write(0x88); // get MSB for a0 33 spi_write(0x88); // get MSB for a0
34 a0_MSB = spi_read(0x00); 34 a0_MSB = spi_read(0x00);
35 spi_write(0x8A); // get LSB for a0 35 spi_write(0x8A); // get LSB for a0
36 a0_LSB = spi_read(0x00); 36 a0_LSB = spi_read(0x00);
37   37  
38 spi_write(0x8C); // get MSB for b1 38 spi_write(0x8C); // get MSB for b1
39 b1_MSB = spi_read(0x00); 39 b1_MSB = spi_read(0x00);
40 spi_write(0x8E); // get LSB for b1 40 spi_write(0x8E); // get LSB for b1
41 b1_LSB = spi_read(0x00); 41 b1_LSB = spi_read(0x00);
42   42  
43 spi_write(0x90); // get MSB for b2 43 spi_write(0x90); // get MSB for b2
44 b2_MSB = spi_read(0x00); 44 b2_MSB = spi_read(0x00);
45 spi_write(0x92); // get LSB for b2 45 spi_write(0x92); // get LSB for b2
46 b2_LSB = spi_read(0x00); 46 b2_LSB = spi_read(0x00);
47   47  
48 spi_write(0x94); // get MSB for c12 48 spi_write(0x94); // get MSB for c12
49 c12_MSB = spi_read(0x00); 49 c12_MSB = spi_read(0x00);
50 spi_write(0x96); // get LSB for c12 50 spi_write(0x96); // get LSB for c12
51 c12_LSB = spi_read(0x00); 51 c12_LSB = spi_read(0x00);
52   52  
53 spi_read(0x00); 53 spi_read(0x00);
54 output_high(CSN_SPI); 54 output_high(CSN_SPI);
55 55
56 // translate to floating point number 56 // translate to floating point number
-   57  
-   58 printf("%d %d %d %d %d %d %d %d ",a0_MSB, a0_LSB,b1_MSB, b1_LSB, b2_MSB, b2_LSB, c12_MSB, c12_LSB);
57 59
58 a0 = ((unsigned int16) a0_MSB << 5) + (a0_LSB >> 3) + (a0_LSB & 0x07)/8.0; 60 a0 = ((unsigned int16) a0_MSB << 5) + (a0_LSB >> 3) + (a0_LSB & 0x07)/8.0;
59 b1 = ((((b1_MSB & 0x1F) * 0x100) + b1_LSB) / 8192.0) - 3; 61 b1 = ((((b1_MSB & 0x1F) * 0x100) + b1_LSB) / 8192.0) - 3;
60 b2 = ((((unsigned int16) (b2_MSB - 0x80) << 8) + b2_LSB)/ 16384.0) - 2; 62 b2 = ((((unsigned int16) (b2_MSB - 0x80) << 8) + b2_LSB)/ 16384.0) - 2;
61 c12 =(((c12_MSB * 0x100) + c12_LSB)/16777216.0); 63 c12 =(((c12_MSB * 0x100) + c12_LSB)/16777216.0);
62 } 64 }
63   65  
64 float MPL_get_pressure() 66 float MPL_get_pressure()
65 { 67 {
66 unsigned int8 LSB_data, MSB_data; 68 unsigned int8 LSB_data, MSB_data;
67 unsigned int16 ADC_pressure, ADC_temperature; 69 unsigned int16 ADC_pressure, ADC_temperature;
68 float Pcomp; 70 float Pcomp;
69   71  
70 output_low(CSN_SPI); //Start temperature and pressure conversion 72 output_low(CSN_SPI); //Start temperature and pressure conversion
71 spi_write(0x24); 73 spi_write(0x24);
72 spi_write(0x00); 74 spi_write(0x00);
73 output_high(CSN_SPI); 75 output_high(CSN_SPI);
74   76  
75 delay_ms(10); 77 delay_ms(10);
76 78
77 output_low(CSN_SPI); // get MSB for Pressure 79 output_low(CSN_SPI); // get MSB for Pressure
78 spi_write(0x80); 80 spi_write(0x80);
79 MSB_data = spi_read(0x00); 81 MSB_data = spi_read(0x00);
80 spi_write(0x82); // get LSB for Pressure 82 spi_write(0x82); // get LSB for Pressure
81 LSB_data = spi_read(0x00); 83 LSB_data = spi_read(0x00);
82 output_high(CSN_SPI); 84 output_high(CSN_SPI);
83   85  
84 ADC_pressure = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable 86 ADC_pressure = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
85   87  
86 output_low(CSN_SPI); 88 output_low(CSN_SPI);
87 spi_write(0x84); 89 spi_write(0x84);
88 MSB_data = spi_read(0x00); 90 MSB_data = spi_read(0x00);
89 spi_write(0x86); // get LSB for Temperature 91 spi_write(0x86); // get LSB for Temperature
90 LSB_data = spi_read(0x00); 92 LSB_data = spi_read(0x00);
91 spi_read(0x00); 93 spi_read(0x00);
92 output_high(CSN_SPI); 94 output_high(CSN_SPI);
93   95  
94 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable 96 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
95 97
96 Pcomp = (a0 + (b1 + c12 * ADC_temperature) * ADC_pressure + b2 * ADC_temperature ); // compute relative compensated pressure 98 Pcomp = (a0 + (b1 + c12 * ADC_temperature) * ADC_pressure + b2 * ADC_temperature ); // compute relative compensated pressure
97   99  
98 return (Pcomp * ((115.0 - 50.0)/1023.0) + 50.0); // return absolute pressure 100 return (Pcomp * ((115.0 - 50.0)/1023.0) + 50.0); // return absolute pressure
99 } 101 }
100   102  
101 float MPL_get_temperature() 103 float MPL_get_temperature()
102 { 104 {
103 unsigned int8 LSB_data, MSB_data; 105 unsigned int8 LSB_data, MSB_data;
104 unsigned int16 ADC_temperature; 106 unsigned int16 ADC_temperature;
105   107  
106 output_low(CSN_SPI); //Start temperature and pressure conversion 108 output_low(CSN_SPI); //Start temperature and pressure conversion
107 spi_write(0x22); 109 spi_write(0x22);
108 spi_write(0x00); 110 spi_write(0x00);
109 output_high(CSN_SPI); 111 output_high(CSN_SPI);
110   112  
111 delay_ms(10); 113 delay_ms(10);
112 114
113 output_low(CSN_SPI); 115 output_low(CSN_SPI);
114 spi_write(0x84); 116 spi_write(0x84);
115 MSB_data = spi_read(0x00); 117 MSB_data = spi_read(0x00);
116 spi_write(0x86); // get LSB for Temperature 118 spi_write(0x86); // get LSB for Temperature
117 LSB_data = spi_read(0x00); 119 LSB_data = spi_read(0x00);
118 spi_read(0x00); 120 spi_read(0x00);
119 output_high(CSN_SPI); 121 output_high(CSN_SPI);
120   122  
121 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable 123 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
122 124
123 return ( ((float) ADC_temperature - 498.0)/-5.35) + 25.0; // return temperature in deg C 125 return ( ((float) ADC_temperature - 498.0)/-5.35) + 25.0; // return temperature in deg C
124 } 126 }
125   127