| 0,0 → 1,125 |
|---|
| /* |
| MPL115A1 SDN - +3.3V (always power on) |
| MPL115A1 #CS - PIN_C2 |
| MPL115A1 DOUT - PIN_C4 |
| MPL115A1 DIN - PIN_C5 |
| MPL115A1 SCLK - PIN_C3 |
| MPL115A1 GND - GND |
| MPL115A1 VDD - +3.3V |
| */ |
| |
| |
| // SPI mode definitions. |
| #define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H) |
| #define SPI_MODE_1 (SPI_L_TO_H) |
| #define SPI_MODE_2 (SPI_H_TO_L) |
| #define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H) |
| |
| float a0; // correctiaon coefficients |
| float b1; |
| float b2; |
| float c12; |
| |
| |
| void MPL_init() |
| { |
| unsigned int8 a0_MSB, a0_LSB; |
| unsigned int8 b1_MSB, b1_LSB; |
| unsigned int8 b2_MSB, b2_LSB; |
| unsigned int8 c12_MSB, c12_LSB; |
| |
| output_low(CSN_SPI); |
| |
| spi_write(0x88); // get MSB for a0 |
| a0_MSB = spi_read(0x00); |
| spi_write(0x8A); // get LSB for a0 |
| a0_LSB = spi_read(0x00); |
| |
| spi_write(0x8C); // get MSB for b1 |
| b1_MSB = spi_read(0x00); |
| spi_write(0x8E); // get LSB for b1 |
| b1_LSB = spi_read(0x00); |
| |
| spi_write(0x90); // get MSB for b2 |
| b2_MSB = spi_read(0x00); |
| spi_write(0x92); // get LSB for b2 |
| b2_LSB = spi_read(0x00); |
| |
| spi_write(0x94); // get MSB for c12 |
| c12_MSB = spi_read(0x00); |
| spi_write(0x96); // get LSB for c12 |
| c12_LSB = spi_read(0x00); |
| |
| spi_read(0x00); |
| output_high(CSN_SPI); |
| |
| // translate to floating point number |
| |
| a0 = ((unsigned int16) a0_MSB << 5) + (a0_LSB >> 3) + (a0_LSB & 0x07)/8.0; |
| b1 = ((((b1_MSB & 0x1F) * 0x100) + b1_LSB) / 8192.0) - 3; |
| b2 = ((((unsigned int16) (b2_MSB - 0x80) << 8) + b2_LSB)/ 16384.0) - 2; |
| c12 =(((c12_MSB * 0x100) + c12_LSB)/16777216.0); |
| } |
| |
| float MPL_get_pressure() |
| { |
| unsigned int8 LSB_data, MSB_data; |
| unsigned int16 ADC_pressure, ADC_temperature; |
| float Pcomp; |
| |
| output_low(CSN_SPI); //Start temperature and pressure conversion |
| spi_write(0x24); |
| spi_write(0x00); |
| output_high(CSN_SPI); |
| |
| delay_ms(10); |
| |
| output_low(CSN_SPI); // get MSB for Pressure |
| spi_write(0x80); |
| MSB_data = spi_read(0x00); |
| spi_write(0x82); // get LSB for Pressure |
| LSB_data = spi_read(0x00); |
| output_high(CSN_SPI); |
| |
| ADC_pressure = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable |
| |
| output_low(CSN_SPI); |
| spi_write(0x84); |
| MSB_data = spi_read(0x00); |
| spi_write(0x86); // get LSB for Temperature |
| LSB_data = spi_read(0x00); |
| spi_read(0x00); |
| output_high(CSN_SPI); |
| |
| ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable |
| |
| Pcomp = (a0 + (b1 + c12 * ADC_temperature) * ADC_pressure + b2 * ADC_temperature ); // compute relative compensated pressure |
| |
| return (Pcomp * ((115.0 - 50.0)/1023.0) + 50.0); // return absolute pressure |
| } |
| |
| float MPL_get_temperature() |
| { |
| unsigned int8 LSB_data, MSB_data; |
| unsigned int16 ADC_temperature; |
| |
| output_low(CSN_SPI); //Start temperature and pressure conversion |
| spi_write(0x22); |
| spi_write(0x00); |
| output_high(CSN_SPI); |
| |
| delay_ms(10); |
| |
| output_low(CSN_SPI); |
| spi_write(0x84); |
| MSB_data = spi_read(0x00); |
| spi_write(0x86); // get LSB for Temperature |
| LSB_data = spi_read(0x00); |
| spi_read(0x00); |
| output_high(CSN_SPI); |
| |
| ADC_temperature = (((unsigned int16) MSB_data << 8) + LSB_data ) >> 6; // conversion of 8bit registers to 16bit variable |
| |
| return ( ((float) ADC_temperature - 498.0)/-5.35) + 27.0; // return temperature in deg C |
| } |
| |