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Improve I2C_TIMINGR register calculation

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This commit is contained in:
Hans Christian Olaussen 2021-03-18 19:26:08 +01:00
parent b30f16fe91
commit ea86fe941b
1 changed files with 23 additions and 14 deletions
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37
src/main/drivers/bus_i2c_hal_init.c
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@ -203,19 +203,20 @@ const i2cHardware_t i2cHardware[I2CDEV_COUNT] = {
i2cDevice_t i2cDevice[I2CDEV_COUNT];
// Values from I2C-SMBus specification
static uint16_t trmax; // Raise time (max)
static uint16_t trmax; // Rise time (max)
static uint16_t tfmax; // Fall time (max)
static uint8_t tsuDATmin; // SDA setup time (min)
static uint8_t thdDATmin; // SDA hold time (min)
static uint16_t tHIGHmin; // High period of SCL clock (min)
static uint16_t tLOWmin; // Low period of SCL clock (min)
// Silicon specific values, from datasheet
static uint8_t tAFmin; // Analog filter delay (min)
static uint8_t tAFmax; // Analog filter delay (max)
static uint16_t tAFmax; // Analog filter delay (max)
// Actual (estimated) values
static uint16_t tr = 100; // Raise time
static uint16_t tf = 100; // Fall time
static uint8_t tAF = 70; // Analog filter delay
static uint16_t tr = 100; // Rise time
static uint16_t tf = 10; // Fall time
/*
* Compute SCLDEL, SDADEL, SCLH and SCLL for TIMINGR register according to reference manuals.
@ -229,12 +230,16 @@ static void i2cClockComputeRaw(uint32_t pclkFreq, int i2cFreqKhz, int presc, int
tfmax = 120;
tsuDATmin = 50;
thdDATmin = 0;
tHIGHmin = 260;
tLOWmin = 500;
} else {
// Fm (Fast mode)
trmax = 300;
tfmax = 300;
tsuDATmin = 100;
thdDATmin = 0;
tHIGHmin = 600;
tLOWmin = 1300;
}
tAFmin = 50;
tAFmax = 90;
@ -249,19 +254,23 @@ static void i2cClockComputeRaw(uint32_t pclkFreq, int i2cFreqKhz, int presc, int
uint32_t SDADELmin = (tfmax + thdDATmin - tAFmin - ((dfcoeff + 3) * tI2cclk)) / ((presc + 1) * tI2cclk);
float tsync1 = tf + tAF + dfcoeff * tI2cclk + 3 * tI2cclk;
float tsync2 = tr + tAF + dfcoeff * tI2cclk + 3 * tI2cclk;
float tsync1 = tf + tAFmin + dfcoeff * tI2cclk + 2 * tI2cclk;
float tsync2 = tr + tAFmin + dfcoeff * tI2cclk + 2 * tI2cclk;
float tSCLHL = tSCL - tsync1 - tsync2;
float SCLHL = tSCLHL / ((presc + 1) * tI2cclk) - 1;
float tSCLH = tHIGHmin * tSCL / (tHIGHmin + tLOWmin) - tsync2;
float tSCLL = tSCL - tSCLH - tsync1 - tsync2;
uint32_t SCLH = SCLHL / 4.75; // STM32CubeMX seems to use a value like this
uint32_t SCLL = (uint32_t)(SCLHL + 0.5f) - SCLH;
uint32_t SCLH = tSCLH / ((presc + 1) * tI2cclk) - 1;
uint32_t SCLL = tSCLL / ((presc + 1) * tI2cclk) - 1;
while (tsync1 + tsync2 + ((SCLH + 1) + (SCLL + 1)) * ((presc + 1) * tI2cclk) < tSCL) {
SCLH++;
}
*scldel = SCLDELmin;
*sdadel = SDADELmin;
*sclh = SCLH - 1;
*scll = SCLL - 1;
*sclh = SCLH;
*scll = SCLL;
}
static uint32_t i2cClockTIMINGR(uint32_t pclkFreq, int i2cFreqKhz, int dfcoeff)
@ -274,7 +283,7 @@ static uint32_t i2cClockTIMINGR(uint32_t pclkFreq, int i2cFreqKhz, int dfcoeff)
uint16_t sclh;
uint16_t scll;
for (int presc = 1; presc < 15; presc++) {
for (int presc = 0; presc < 15; presc++) {
i2cClockComputeRaw(pclkFreq, i2cFreqKhz, presc, dfcoeff, &scldel, &sdadel, &sclh, &scll);
// If all fields are not overflowing, return TIMINGR.