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[CC1101] Reworked exp/mant calculation

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This commit is contained in:
jgromes 2019-01-13 19:47:56 +01:00
parent bd2596efac
commit 819297060b
2 changed files with 93 additions and 121 deletions
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186
src/modules/CC1101.cpp
View file

@ -4,7 +4,7 @@ CC1101::CC1101(Module* module) : PhysicalLayer(CC1101_CRYSTAL_FREQ, CC1101_DIV_E
_mod = module;
}
int16_t CC1101::begin(float freq, float br, uint16_t rxBw, float freqDev) {
int16_t CC1101::begin(float freq, float br, float rxBw, float freqDev) {
// set module properties
_mod->SPIreadCommand = CC1101_CMD_READ;
_mod->SPIwriteCommand = CC1101_CMD_WRITE;
@ -91,6 +91,20 @@ int16_t CC1101::transmit(uint8_t* data, size_t len, uint8_t addr) {
return(ERR_NONE);
}
int16_t CC1101::receive(String& str, size_t len) {
// create temporary array to store received data
char* data = new char[len + 1];
int16_t state = CC1101::receive((uint8_t*)data, len);
// if packet was received successfully, copy data into String
if(state == ERR_NONE) {
str = String(data);
}
delete[] data;
return(state);
}
int16_t CC1101::receive(uint8_t* data, size_t len) {
// TODO
@ -160,119 +174,36 @@ int16_t CC1101::setBitRate(float br) {
SPIsendCommand(CC1101_CMD_IDLE);
// calculate exponent and mantisa values
for(uint8_t e = 14; e > 0; e++) {
float intervalStart = 406250.00/(float)(1 << (14 - e));
if((br * 1000.0) > intervalStart) {
float stepSize = intervalStart/256.0;
uint8_t m = (uint8_t)(((br * 1000.0) - intervalStart) / stepSize);
uint8_t e, m;
getExpMant(br * 1000.0, 256, 28, 14, e, m);
// set bit rate value
int16_t state = _mod->SPIsetRegValue(CC1101_REG_MDMCFG4, e, 3, 0);
state |= _mod->SPIsetRegValue(CC1101_REG_MDMCFG3, m);
return(state);
}
}
return(ERR_UNKNOWN);
}
int16_t CC1101::setRxBandwidth(uint16_t rxBw) {
int16_t CC1101::setRxBandwidth(float rxBw) {
// check allowed bandwidth range
uint8_t bwMant, bwExp;
switch(rxBw) {
case 58:
bwMant = 3;
bwExp = 3;
break;
case 68:
bwMant = 2;
bwExp = 3;
break;
case 81:
bwMant = 1;
bwExp = 3;
break;
case 102:
bwMant = 0;
bwExp = 3;
break;
case 116:
bwMant = 3;
bwExp = 2;
break;
case 135:
bwMant = 2;
bwExp = 2;
break;
case 162:
bwMant = 1;
bwExp = 2;
break;
case 203:
bwMant = 0;
bwExp = 2;
break;
case 232:
bwMant = 3;
bwExp = 1;
break;
case 270:
bwMant = 2;
bwExp = 1;
break;
case 325:
bwMant = 1;
bwExp = 1;
break;
case 406:
bwMant = 0;
bwExp = 1;
break;
case 464:
bwMant = 3;
bwExp = 0;
break;
case 541:
bwMant = 2;
bwExp = 0;
break;
case 650:
bwMant = 1;
bwExp = 0;
break;
case 812:
bwMant = 0;
bwExp = 0;
break;
default:
if(!((rxBw >= 58) && (rxBw <= 812))) {
return(ERR_INVALID_RX_BANDWIDTH);
}
// set mode to standby
SPIsendCommand(CC1101_CMD_IDLE);
// calculate exponent and mantisa values
for(int8_t e = 3; e >= 0; e--) {
for(int8_t m = 3; m >= 0; m --) {
float point = (CC1101_CRYSTAL_FREQ * 1000000.0)/(8 * (m + 4) * ((uint32_t)1 << e));
if(abs((rxBw * 1000.0) - point) <= 0.001) {
// set Rx channel filter bandwidth
return(_mod->SPIsetRegValue(CC1101_REG_MDMCFG4, (bwExp << 6) | (bwMant << 4), 7, 4));
}
return(_mod->SPIsetRegValue(CC1101_REG_MDMCFG4, (e << 6) | (m << 4), 7, 4));
}
}
}
int16_t CC1101::directMode() {
// set mode to standby
SPIsendCommand(CC1101_CMD_IDLE);
// set GDO0 and GDO2 mapping
int16_t state = _mod->SPIsetRegValue(CC1101_REG_IOCFG0, CC1101_GDOX_SERIAL_CLOCK , 5, 0);
state |= _mod->SPIsetRegValue(CC1101_REG_IOCFG2, CC1101_GDOX_SERIAL_DATA_SYNC , 5, 0);
// set continuous mode
state |= _mod->SPIsetRegValue(CC1101_REG_PKTCTRL0, CC1101_PKT_FORMAT_SYNCHRONOUS, 5, 4);
return(state);
}
int16_t CC1101::config() {
// enable autmatic frequency synthesizer calibration
int16_t state = _mod->SPIsetRegValue(CC1101_REG_MCSM0, CC1101_FS_AUTOCAL_IDLE_TO_RXTX, 5, 4);
return(state);
return(ERR_UNKNOWN);
}
int16_t CC1101::setFrequencyDeviation(float freqDev) {
@ -292,20 +223,59 @@ int16_t CC1101::setFrequencyDeviation(float freqDev) {
SPIsendCommand(CC1101_CMD_IDLE);
// calculate exponent and mantisa values
for(uint8_t e = 7; e > 0; e++) {
float intervalStart = 203125.00/(float)(1 << (7 - e));
if((freqDev * 1000.0) > intervalStart) {
float stepSize = intervalStart/8.0;
uint8_t m = (uint8_t)(((freqDev * 1000.0) - intervalStart) / stepSize);
uint8_t e, m;
getExpMant(freqDev * 1000.0, 8, 17, 7, e, m);
// set frequency deviation value
int16_t state = _mod->SPIsetRegValue(CC1101_REG_DEVIATN, (e << 4), 6, 4);
state |= _mod->SPIsetRegValue(CC1101_REG_DEVIATN, m, 2, 0);
return(state);
}
}
}
return(ERR_UNKNOWN);
int16_t CC1101::config() {
// enable autmatic frequency synthesizer calibration
int16_t state = _mod->SPIsetRegValue(CC1101_REG_MCSM0, CC1101_FS_AUTOCAL_IDLE_TO_RXTX, 5, 4);
return(state);
}
int16_t CC1101::directMode() {
// set mode to standby
SPIsendCommand(CC1101_CMD_IDLE);
// set GDO0 and GDO2 mapping
int16_t state = _mod->SPIsetRegValue(CC1101_REG_IOCFG0, CC1101_GDOX_SERIAL_CLOCK , 5, 0);
state |= _mod->SPIsetRegValue(CC1101_REG_IOCFG2, CC1101_GDOX_SERIAL_DATA_SYNC , 5, 0);
// set continuous mode
state |= _mod->SPIsetRegValue(CC1101_REG_PKTCTRL0, CC1101_PKT_FORMAT_SYNCHRONOUS, 5, 4);
return(state);
}
void CC1101::getExpMant(float target, uint8_t mantOffset, uint8_t divExp, uint8_t expMax, uint8_t& exp, uint8_t& mant) {
// get table origin point (exp = 0, mant = 0)
float origin = (mantOffset * CC1101_CRYSTAL_FREQ * 1000000.0)/((uint32_t)1 << divExp);
// iterate over possible exponent values
for(int8_t e = expMax; e >= 0; e--) {
// get table column start value (exp = e, mant = 0);
float intervalStart = ((uint32_t)1 << e) * origin;
// check if target value is in this column
if(target >= intervalStart) {
// save exponent value
exp = e;
// calculate size of step between table rows
float stepSize = intervalStart/(float)mantOffset;
// get target point position (exp = e, mant = m)
mant = ((target - intervalStart) / stepSize);
// we only need the first match, terminate
return;
}
}
}
int16_t CC1101::SPIgetRegValue(uint8_t reg, uint8_t msb, uint8_t lsb) {
@ -317,9 +287,9 @@ uint8_t CC1101::SPIreadRegister(uint8_t reg) {
}
void CC1101::SPIsendCommand(uint8_t cmd) {
digitalWrite(_mod->cs(), LOW);
digitalWrite(_mod->getCs(), LOW);
SPI.beginTransaction(SPISettings(2000000, MSBFIRST, SPI_MODE0));
SPI.transfer(cmd);
SPI.endTransaction();
digitalWrite(_mod->cs(), HIGH);
digitalWrite(_mod->getCs(), HIGH);
}

6
src/modules/CC1101.h
View file

@ -498,10 +498,11 @@ class CC1101: public PhysicalLayer {
CC1101(Module* module);
// basic methods
int16_t begin(float freq = 868.0, float br = 115.2, uint16_t rxBw = 203, float freqDev = 48.0);
int16_t begin(float freq = 868.0, float br = 115.2, float rxBw = 325.0, float freqDev = 48.0);
int16_t transmit(String& str, uint8_t addr = 0);
int16_t transmit(const char* str, uint8_t addr = 0);
int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0);
int16_t receive(String& str, size_t len = 0);
int16_t receive(uint8_t* data, size_t len);
int16_t standby();
int16_t transmitDirect(uint32_t FRF = 0);
@ -510,7 +511,7 @@ class CC1101: public PhysicalLayer {
// configuration methods
int16_t setFrequency(float freq);
int16_t setBitRate(float br);
int16_t setRxBandwidth(uint16_t rxBw);
int16_t setRxBandwidth(float rxBw);
int16_t setFrequencyDeviation(float freqDev);
private:
@ -518,6 +519,7 @@ class CC1101: public PhysicalLayer {
int16_t config();
int16_t directMode();
void getExpMant(float target, uint8_t mantOffset, uint8_t divExp, uint8_t expMax, uint8_t& exp, uint8_t& mant);
// SPI read overrides to set access bit for status registers
int16_t SPIgetRegValue(uint8_t reg, uint8_t msb = 7, uint8_t lsb = 0);