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STM32 : Cordic support for Atan2 #68

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STM32 : Cordic support for Atan2 #68

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58 changes: 43 additions & 15 deletions src/utilities/stm32math/STM32G4CORDICTrigFunctions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,38 +46,66 @@ bool SimpleFOC_CORDIC_Config(void){
return true;
};

static bool arg2_modified = false;


float _sin(float a) {
a = fmod(a, _2PI);
if (a>_PI) a -= _2PI;
if (a<-_PI) a += _2PI;
CORDIC->WDATA = (q31_t)((a / _PI) * 0x80000000);
q31_t out_cos = (int32_t)CORDIC->RDATA; // read cosine result
q31_t out_sin = (int32_t)CORDIC->RDATA; // read sine result
return (float)out_sin / (float)0x80000000;
float s, c;
_sincos(a, &s, &c);
return s;
}

float _cos(float a) {
a = fmod(a, _2PI);
if (a>_PI) a -= _2PI;
if (a<-_PI) a += _2PI;
CORDIC->WDATA = (q31_t)((a / _PI) * 0x80000000);
q31_t out_cos = (int32_t)CORDIC->RDATA; // read cosine result
q31_t out_sin = (int32_t)CORDIC->RDATA; // read sine result
return (float)out_cos / (float)0x80000000;
float s, c;
_sincos(a, &s, &c);
return c;
}

void _sincos(float a, float* s, float* c) {
a = fmod(a, _2PI);
if (a>_PI) a -= _2PI;
if (a<-_PI) a += _2PI;
if (a<-_PI) a += _2PI;
LL_CORDIC_SetFunction(CORDIC, LL_CORDIC_FUNCTION_COSINE);
CORDIC->WDATA = (q31_t)((a / _PI) * 0x80000000);
if (arg2_modified)
{
CORDIC->WDATA = (q31_t)((1.f) * 0x80000000);
}
q31_t out_cos = (int32_t)CORDIC->RDATA; // read cosine result
q31_t out_sin = (int32_t)CORDIC->RDATA; // read sine result
*c = (float)out_cos / (float)0x80000000;
*s = (float)out_sin / (float)0x80000000;
if (arg2_modified)
{
LL_CORDIC_SetNbWrite(CORDIC, LL_CORDIC_NBWRITE_1);
arg2_modified = false;
}
}

void _atan2mod(float y, float x, float* phase, float* modulus)
{
float absx = abs(x), absy = abs(y);
float xbigger = abs(x) >= abs(y);
float scaler = (xbigger ? absx : absy) * 1.5f; //multiply scaler by 1.5 to avoid saturating modulus
LL_CORDIC_SetFunction(CORDIC, LL_CORDIC_FUNCTION_PHASE);
if (!arg2_modified)
{
arg2_modified = true;
LL_CORDIC_SetNbWrite(CORDIC, LL_CORDIC_NBWRITE_2);
}
CORDIC->WDATA = (q31_t)((x / scaler) * 0x80000000);
CORDIC->WDATA = (q31_t)((y / scaler) * 0x80000000);
q31_t out_phase = (int32_t)CORDIC->RDATA; // read phase result
q31_t out_modulus = (int32_t)CORDIC->RDATA; // read modulus result
*phase = (float)out_phase * _PI / (float)0x80000000;
*modulus = (float)out_modulus / (float)0x80000000 * scaler;
}

float _atan2(float y, float x)
{
float phase, modulus;
_atan2mod(y, x, &phase, &modulus);
return phase;
}

#endif