Mercurial > public > ostc4
changeset 335:c11ce8c885d3 PressureMeasure_Improvment
Use average calculation for pressure: precondition was that pressure values jittered +- 10 HPa from one capture (once a second) to the other. Basically pressure is measured several times a second => using these values in an additional history calculation reduces the jitter down to +-1 per second
Additionaly a similar function has been added to the surface pressure capture to further reduce the jitter in long therm measurements (once a minute)
author | ideenmodellierer |
---|---|
date | Tue, 13 Aug 2019 21:46:26 +0200 |
parents | 143fe85f82a2 |
children | 449e9e9632e4 |
files | Small_CPU/Src/pressure.c |
diffstat | 1 files changed, 40 insertions(+), 27 deletions(-) [+] |
line wrap: on
line diff
--- a/Small_CPU/Src/pressure.c Sun Aug 04 11:01:06 2019 +0200 +++ b/Small_CPU/Src/pressure.c Tue Aug 13 21:46:26 2019 +0200 @@ -49,6 +49,8 @@ #define PRESSURE_HISTORY_SIZE (8u) #define PRESSURE_JUMP_VALID_MBAR (500.0f) /* values are measure several times a second => jumps > 5m very unlikely */ +#define PRESSURE_SURFACE_QUE (30u) /* history buffer [minutes] for past pressure measurements */ + static uint16_t get_ci_by_coef_num(uint8_t coef_num); //void pressure_calculation_new(void); //void pressure_calculation_old(void); @@ -79,7 +81,7 @@ static float ambient_temperature = 0; static float ambient_pressure_mbar = 1000.0; static float surface_pressure_mbar = 1000.0; -static float surface_ring_mbar[31] = { 0 }; +static float surface_ring_mbar[PRESSURE_SURFACE_QUE] = { 0 }; static float pressure_history_mbar[PRESSURE_HISTORY_SIZE]; @@ -103,10 +105,12 @@ void init_surface_ring(void) { - surface_ring_mbar[0] = 0; - for(int i=1; i<31; i++) - surface_ring_mbar[i] = ambient_pressure_mbar; - surface_pressure_mbar = ambient_pressure_mbar; + if(surface_ring_mbar[0] == 0) /* only initialize once. Keep value in place in case of an i2c recovery */ + { + for(int i=0; i<PRESSURE_SURFACE_QUE; i++) + surface_ring_mbar[i] = ambient_pressure_mbar; + surface_pressure_mbar = ambient_pressure_mbar; + } } void init_pressure_history(void) @@ -117,33 +121,34 @@ } } -/* the ring has one place with 0 - * after that comes the oldest value - * the new pressure is written in this hole - * the oldest value is read and then the new hole -*/ + void update_surface_pressure(uint8_t call_rhythm_seconds) { - secondCounterSurfaceRing += call_rhythm_seconds; - - if(secondCounterSurfaceRing < 60) - return; - - secondCounterSurfaceRing = 0; - + static uint8_t writeIndex = 0; /* Reinitialization will reset all entries to the same value => no need to reinit write index */ + static uint8_t avgCount = 0; + static float runningAvg = 0; + if(is_init_pressure_done()) { - int hole; - for(hole=30;hole>0;hole--) - if(surface_ring_mbar[hole] == 0) { break; } + runningAvg = (runningAvg * avgCount + ambient_pressure_mbar) / (avgCount +1); + avgCount++; + secondCounterSurfaceRing += call_rhythm_seconds; - surface_ring_mbar[hole] = ambient_pressure_mbar; + if(secondCounterSurfaceRing >= 60) + { + surface_ring_mbar[writeIndex] = runningAvg; + writeIndex++; /* the write index is now pointing to the oldest value in the buffer which will be overwritten next time */ - hole++; - if(hole > 30) - hole = 0; - surface_pressure_mbar = surface_ring_mbar[hole]; - surface_ring_mbar[hole] = 0; + if(writeIndex == PRESSURE_SURFACE_QUE) + { + writeIndex = 0; + } + + surface_pressure_mbar = surface_ring_mbar[writeIndex]; /* 30 minutes old measurement */ + + secondCounterSurfaceRing = 0; + avgCount = 1; /* use the current value as starting point but restart the weight decrement of the measurements */ + } } } @@ -449,6 +454,9 @@ static void pressure_calculation_AN520_004_mod_MS5803_30BA__09_2015(void) { + static float runningAvg = 0; + static uint8_t avgCnt = 0; + uint32_t local_D1; // ADC value of the pressure conversion uint32_t local_D2; // ADC value of the temperature conversion int32_t local_Px10; // compensated pressure value @@ -516,7 +524,12 @@ calc_pressure = ((float)local_Px10) / 10; if(pressure_plausible(calc_pressure)) { - ambient_pressure_mbar = calc_pressure; + runningAvg = (avgCnt * runningAvg + calc_pressure) / (avgCnt + 1); + if (avgCnt < 10) /* build an average considering the last measurements to a a weight "1 of 10" */ + { /* Main reason for this is the jitter of up to +-10 HPa in surface mode which is caused */ + avgCnt++; /* by the measurement range of the sensor which is focused on under water pressure measurement */ + } + ambient_pressure_mbar = runningAvg; } }