First draft HMC5883 magnetometer sensor using physical quantities, outputting via serial port using std::cout on mbed os 5
main.cpp
- Committer:
- skyscraper
- Date:
- 2020-03-22
- Revision:
- 1:e11ab941748b
- Parent:
- 0:37dbfb036586
- Child:
- 2:9ffb2f18756b
File content as of revision 1:e11ab941748b:
#include "mbed.h" #include <string> #include <array> #include <iostream> #include <ratio> #include <type_traits> #include <quan/out/magnetic_flux_density.hpp> #include <quan/three_d/out/vect.hpp> #include <quan/max.hpp> #include <quan/min.hpp> namespace { DigitalOut led2(LED2); } // namespace /* paradigm input stream synchronous/asynchronous Ideally it updates in background You can be notified of update in callback or just read */ template<typename SensorUnit> struct Sensor { typedef SensorUnit sensor_unit_t; // TODO status_t get_status()const; virtual bool open() = 0; virtual bool read(sensor_unit_t const & current_value) const = 0; virtual bool close() = 0; }; namespace { /* 00 Configuration Register A R/W 01 Configuration Register B R/W 02 Mode Register R/W 03 Data Output X MSB Register R 04 Data Output X LSB Register R 05 Data Output Z MSB Register R 06 Data Output Z LSB Register R 07 Data Output Y MSB Register R 08 Data Output Y LSB Register R 09 Status Register R 10 Identification Register A R 11 Identification Register B R 12 Identification Register C R */ I2C i2c(I2C_SDA, I2C_SCL ); constexpr uint8_t i2c_addr = 0x3D; constexpr char cfg_regA = 0; constexpr char cfg_regB = 1; constexpr char mode_reg = 2; constexpr char dout_reg = 3; constexpr char status_reg = 9; constexpr char id_regA = 10U; // Set reg index to idx_in // return true if successful bool mag_set_reg_idx(uint8_t idx_in) { char const idx = static_cast<char>(idx_in); bool const result = (i2c.write(i2c_addr,&idx,1) == 0); if(result) { return true; } else { std::cout << "mag_set_reg_idx failed\n"; return false; } } // Write reg at idx with val // return true if successful bool mag_write_reg(uint8_t idx, uint8_t val) { char ar[2] = {idx,val}; bool const result = (i2c.write(i2c_addr,ar,2) == 0); if(result) { return true; } else { std::cout << " mag_write_reg failed\n"; return false; } } // Read reg at idx to result // return true if successfull bool mag_get_reg(uint8_t idx_in, uint8_t& result) { if ( mag_set_reg_idx(idx_in)) { char result1 = 0; if (i2c.read(i2c_addr,&result1,1) == 0) { result = result1; return true; } else { std::cout << "mag_get_reg read failed\n"; return false; } } else { return false; } } // Update value in reg using and and or masks // reg <-- (reg & and_val) | or_val // return true if successfull bool mag_modify_reg(uint8_t idx, uint8_t and_val, uint8_t or_val) { uint8_t cur_val = 0; if(mag_get_reg(idx,cur_val)) { uint8_t const new_val = (cur_val & and_val ) | or_val; return mag_write_reg(idx,new_val); } else { return false; } } // probe for the HMC5883 on I2C // return true if found bool mag_detected() { if ( mag_set_reg_idx(id_regA) ) { char id_input[4]; if(i2c.read(i2c_addr,id_input,3) == 0) { id_input[3] = '\0'; bool const is_hmc = (strcmp(id_input,"H43") == 0); if (is_hmc) { return true; } else { std::cout << "hmc5883 ID string didnt match\n"; return false; } } else { std::cout << "id mag read failed\n"; return false; } } else { return false; } } // terminal loop, printing message periodically void loop_forever(std::string const & str) { // stop but print error dynamically int count = 0; for (;;) { led2 = 1; std::cout << str << " " << count++ << '\n'; ThisThread::sleep_for(200U); led2 = 0; ThisThread::sleep_for(800U); } } bool mag_set_samples_average(int n_samples) { uint8_t or_val = 0; switch (n_samples) { case 1 : or_val = 0b00U << 5U; break; case 2 : or_val = 0b01U << 5U; break; case 4 : or_val = 0b10U << 5U; break; case 8 : or_val = 0b11U << 5U; break; default: std::cout << "mag_set_samples_average : invalid n_samples (" << n_samples << ")\n"; return false; } uint8_t constexpr and_val = ~(0b11 << 5U); return mag_modify_reg(cfg_regA,and_val,or_val); } /* data rate 0.75, 1.5, 3 ,7.5, 15 (Default) , 30, 75 */ namespace detail { template <int N, int D=1> struct mag_data_rate_id; // values are mag settings for each data rate template <> struct mag_data_rate_id<3,4> : std::integral_constant<uint8_t,(0b000U << 2U)> {}; template <> struct mag_data_rate_id<3,2> : std::integral_constant<uint8_t,(0b001U << 2U)> {}; template <> struct mag_data_rate_id<3> : std::integral_constant<uint8_t,(0b010U << 2U)> {}; template <> struct mag_data_rate_id<15,2> : std::integral_constant<uint8_t,(0b011U << 2U)> {}; template <> struct mag_data_rate_id<15> : std::integral_constant<uint8_t,(0b100U << 2U)> {}; template <> struct mag_data_rate_id<30> : std::integral_constant<uint8_t,(0b101U << 2U)> {}; template <> struct mag_data_rate_id<75> : std::integral_constant<uint8_t,(0b110U << 2U)> {}; } // detail template <int N, int D=1> inline bool mag_set_data_rate() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b111U << 2U)); uint8_t constexpr or_val = detail::mag_data_rate_id<N,D>::value; return mag_modify_reg(cfg_regA,and_val,or_val); } bool mag_set_positive_bias() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b01U; return mag_modify_reg(cfg_regA,and_val,or_val); } bool mag_set_negative_bias() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b10U; return mag_modify_reg(cfg_regA,and_val,or_val); } bool mag_clear_bias() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b00U; return mag_modify_reg(cfg_regA,and_val,or_val); } QUAN_QUANTITY_LITERAL(magnetic_flux_density,gauss); QUAN_QUANTITY_LITERAL(magnetic_flux_density,milli_gauss); QUAN_QUANTITY_LITERAL(magnetic_flux_density,uT); // per lsb defualt resolution quan::magnetic_flux_density::uT mag_resolution = 0.92_milli_gauss; // range before saturation quan::magnetic_flux_density::uT mag_range = 1.3_gauss; // set +- range // sets the nearest greater equal +-range to abs(range_in) bool mag_set_range(quan::magnetic_flux_density::uT const & range_in) { uint8_t or_value = 0; auto const range = abs(range_in); if ( range <= 0.88_gauss) { or_value = 0b001U << 5U ; mag_range = 0.88_gauss; mag_resolution = 0.73_milli_gauss; } else if (range <= 1.3_gauss) { or_value = 0b001U << 5U ; mag_range = 1.3_gauss; mag_resolution = 0.92_milli_gauss; } else if (range <= 1.9_gauss) { or_value = 0b010U << 5U ; mag_range = 1.9_gauss; mag_resolution = 1.22_milli_gauss; } else if (range <= 2.5_gauss) { or_value = 0b011U << 5U ; mag_range = 2.5_gauss; mag_resolution = 1.52_milli_gauss; } else if (range <= 4.0_gauss) { or_value = 0b100U << 5U ; mag_range = 4.0_gauss; mag_resolution = 2.27_milli_gauss; } else if (range <= 4.7_gauss) { or_value = 0b101U << 5U ; mag_range = 4.7_gauss; mag_resolution = 2.56_milli_gauss; } else if (range <=5.6_gauss) { or_value = 0b110U << 5U ; mag_range = 5.6_gauss; mag_resolution = 3.03_milli_gauss; } else if ( range <= 8.1_gauss) { or_value = 0b111U << 5U ; mag_range = 8.1_gauss; mag_resolution = 4.35_milli_gauss; } else { quan::magnetic_flux_density::uT constexpr max_range = 8.1_gauss; std::cout << "range too big: max +- range = " << max_range <<"\n"; return false; } uint8_t constexpr and_val = static_cast<uint8_t>(~(0b111U << 5U)); std::cout << "mag range set to : +- " << mag_range <<'\n'; return mag_modify_reg(cfg_regB,and_val,or_value); } bool mag_set_continuous_measurement_mode() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b00U; return mag_modify_reg(mode_reg,and_val,or_val); } bool mag_set_single_measurement_mode() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b01U; return mag_modify_reg(mode_reg,and_val,or_val); } bool mag_set_idle_mode() { uint8_t constexpr and_val = static_cast<uint8_t>(~(0b11U )); uint8_t constexpr or_val = 0b10U; return mag_modify_reg(mode_reg,and_val,or_val); } bool mag_data_ready() { uint8_t result = 0; if ( mag_get_reg(status_reg, result)) { return (result & 0b1U) != 0U; } else { std::cout << "mag data ready failed\n"; return false; } } bool mag_data_locked() { uint8_t result = 0; if ( mag_get_reg(status_reg, result)) { return (result & 0b10U) != 0U; } else { std::cout << "mag data locked failed\n"; return false; } } // assume mag_data_ready has returned true before call bool mag_read(quan::three_d::vect<quan::magnetic_flux_density::uT> & v) { if( mag_set_reg_idx(dout_reg)) { char arr[7]; if(i2c.read(i2c_addr,arr,7) == 0) { // TODO check status reg arr[6] // if quan::three_d::vect<int16_t> temp; temp.x = static_cast<int16_t>(arr[1]) + ( static_cast<int16_t>(arr[0]) << 8U); temp.y = static_cast<int16_t>(arr[5]) + ( static_cast<int16_t>(arr[4]) << 8U); temp.z = static_cast<int16_t>(arr[3]) + ( static_cast<int16_t>(arr[2]) << 8U); v = temp * mag_resolution; return true; } else { std::cout << "mag_read failed\n"; return false; } } else { return false; } } bool mag_do_single_measurement(quan::three_d::vect<quan::magnetic_flux_density::uT>& result) { if ( ! mag_set_single_measurement_mode()) { return false; } while (! mag_data_ready()) { ThisThread::sleep_for(5U); } return mag_read(result); } bool mag_get_offsets(quan::three_d::vect<quan::magnetic_flux_density::uT> & result) { // set single measurement mode // to prevent saturation mag_set_range(5.7_gauss); quan::three_d::vect<quan::magnetic_flux_density::uT> mSet; // throw away first mag_do_single_measurement(mSet); mag_set_positive_bias(); mag_do_single_measurement(mSet); std::cout << "mSet = " << mSet <<'\n'; mag_set_negative_bias(); quan::three_d::vect<quan::magnetic_flux_density::uT> mReset; mag_do_single_measurement(mReset); mag_clear_bias(); std::cout << "mReset = " << mReset <<'\n'; result = (mSet - mReset )/2; std::cout << "result = " << result << '\n'; return true; } }// namespace int main() { std::cout << "HMC5883 test\n"; //wait for mag to init ThisThread::sleep_for(500U); bool success = false; if ( mag_detected()) { success = true; std::cout << "Detected a HMC5883\n"; } else { loop_forever("Failed to detect HMC5883"); } /* for ( int i = 0; i < 5; ++i){ mag_get_offsets(offsets); ThisThread::sleep_for(100U); } */ // N.b after offsets removed mag was reading around 33.6 uT, so not bad! constexpr auto earth_magnetic_field_flux_density = 31.869_uT; success = mag_set_samples_average(8) && mag_set_data_rate<3,4>() && // N.B if offsets are large then may need to set larger range // prob need to cycle through looking for best range // so this may not work mag_set_range( earth_magnetic_field_flux_density * 2U); if ( !success) { loop_forever("HMC5883 setup failed"); } // calculate the offsets dynamically by averaging // the min and max over time quan::three_d::vect<quan::magnetic_flux_density::uT> voffsets; quan::three_d::vect<quan::magnetic_flux_density::uT> vmax; quan::three_d::vect<quan::magnetic_flux_density::uT> vmin; auto prev = Kernel::get_ms_count(); for (;;) { quan::three_d::vect<quan::magnetic_flux_density::uT> values; if(mag_do_single_measurement(values)) { vmax.x = quan::max(vmax.x,values.x); vmax.y = quan::max(vmax.y,values.y); vmax.z = quan::max(vmax.z,values.z); vmin.x = quan::min(vmin.x,values.x); vmin.y = quan::min(vmin.y,values.y); vmin.z = quan::min(vmin.z,values.z); voffsets = (vmin + vmax)/2.f; values -= voffsets; std::cout << "val = " << values << '\n'; std::cout << "off = " << voffsets << "\n\n"; } else { std::cout << "mag read failed\n"; } ThisThread::sleep_for(10U); auto now = Kernel::get_ms_count(); if (( now - prev)> 500){ prev = now; led2 = ! led2; } } }