Rev Author Line No. Line
2778 kaklik 1 /*
2 MPL115A1 SDN - +3.3V (always power on)
3 MPL115A1 #CS - PIN_C2
4 MPL115A1 DOUT - PIN_C4
5 MPL115A1 DIN - PIN_C5
6 MPL115A1 SCLK - PIN_C3
7 MPL115A1 GND - GND
8 MPL115A1 VDD - +3.3V
9 */
10  
11  
12 // SPI mode definitions.
13 #define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
14 #define SPI_MODE_1 (SPI_L_TO_H)
15 #define SPI_MODE_2 (SPI_H_TO_L)
16 #define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
17  
18 float a0; // correctiaon coefficients
19 float b1;
20 float b2;
21 float c12;
22  
23  
24 void MPL_init()
25 {
26 unsigned int8 a0_MSB, a0_LSB;
27 unsigned int8 b1_MSB, b1_LSB;
28 unsigned int8 b2_MSB, b2_LSB;
29 unsigned int8 c12_MSB, c12_LSB;
30  
31 output_low(CSN_SPI);
32  
33 spi_write(0x88); // get MSB for a0
34 a0_MSB = spi_read(0x00);
35 spi_write(0x8A); // get LSB for a0
36 a0_LSB = spi_read(0x00);
37  
38 spi_write(0x8C); // get MSB for b1
39 b1_MSB = spi_read(0x00);
40 spi_write(0x8E); // get LSB for b1
41 b1_LSB = spi_read(0x00);
42  
43 spi_write(0x90); // get MSB for b2
44 b2_MSB = spi_read(0x00);
45 spi_write(0x92); // get LSB for b2
46 b2_LSB = spi_read(0x00);
47  
48 spi_write(0x94); // get MSB for c12
49 c12_MSB = spi_read(0x00);
50 spi_write(0x96); // get LSB for c12
51 c12_LSB = spi_read(0x00);
52  
53 spi_read(0x00);
54 output_high(CSN_SPI);
55  
56 // translate to floating point number
3375 kaklik 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);
2778 kaklik 59  
60 a0 = ((unsigned int16) a0_MSB << 5) + (a0_LSB >> 3) + (a0_LSB & 0x07)/8.0;
61 b1 = ((((b1_MSB & 0x1F) * 0x100) + b1_LSB) / 8192.0) - 3;
62 b2 = ((((unsigned int16) (b2_MSB - 0x80) << 8) + b2_LSB)/ 16384.0) - 2;
63 c12 =(((c12_MSB * 0x100) + c12_LSB)/16777216.0);
64 }
65  
66 float MPL_get_pressure()
67 {
68 unsigned int8 LSB_data, MSB_data;
69 unsigned int16 ADC_pressure, ADC_temperature;
70 float Pcomp;
71  
72 output_low(CSN_SPI); //Start temperature and pressure conversion
73 spi_write(0x24);
74 spi_write(0x00);
75 output_high(CSN_SPI);
76  
77 delay_ms(10);
78  
79 output_low(CSN_SPI); // get MSB for Pressure
80 spi_write(0x80);
81 MSB_data = spi_read(0x00);
82 spi_write(0x82); // get LSB for Pressure
83 LSB_data = spi_read(0x00);
84 output_high(CSN_SPI);
85  
86 ADC_pressure = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
87  
88 output_low(CSN_SPI);
89 spi_write(0x84);
90 MSB_data = spi_read(0x00);
91 spi_write(0x86); // get LSB for Temperature
92 LSB_data = spi_read(0x00);
93 spi_read(0x00);
94 output_high(CSN_SPI);
95  
96 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
97  
98 Pcomp = (a0 + (b1 + c12 * ADC_temperature) * ADC_pressure + b2 * ADC_temperature ); // compute relative compensated pressure
99  
100 return (Pcomp * ((115.0 - 50.0)/1023.0) + 50.0); // return absolute pressure
101 }
102  
103 float MPL_get_temperature()
104 {
105 unsigned int8 LSB_data, MSB_data;
106 unsigned int16 ADC_temperature;
107  
108 output_low(CSN_SPI); //Start temperature and pressure conversion
109 spi_write(0x22);
110 spi_write(0x00);
111 output_high(CSN_SPI);
112  
113 delay_ms(10);
114  
115 output_low(CSN_SPI);
116 spi_write(0x84);
117 MSB_data = spi_read(0x00);
118 spi_write(0x86); // get LSB for Temperature
119 LSB_data = spi_read(0x00);
120 spi_read(0x00);
121 output_high(CSN_SPI);
122  
123 ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable
124  
125 return ( ((float) ADC_temperature - 498.0)/-5.35) + 25.0; // return temperature in deg C
126 }
127