/**
* Reset 1-wire bus (~1 ms).
*/
static inline uint8_t reset(void)
{
uint8_t tmp = 0;
uint8_t result = 0;
TIM1_SetAutoreload(485);
TIM1->CR1 |= TIM1_CR1_CEN;
OW_PORT->ODR |= OW_OUT;
while (TIM1->CR1 & TIM1_CR1_CEN);
OW_PORT->ODR &= ~OW_OUT;
TIM1_ClearFlag(TIM1_FLAG_UPDATE);
// Wait once again, sample within 100 mks
TIM1->CR1 |= TIM1_CR1_CEN;
while (TIM1->CR1 & TIM1_CR1_CEN)
{
tmp = TIM1->CNTRH;
if (TIM1->CNTRL >= RESET_TIME)
break;
}
result = (OW_PORT->IDR & OW_IN) == 0;
// Wait for the end of reset period.
while (TIM1->CR1 & TIM1_CR1_CEN);
TIM1_ClearFlag(TIM1_FLAG_UPDATE);
TIM1_SetAutoreload(60);
return result;
}
/**
* 1-wire read cycle.
* Drive line low for 1 mks, then release line, wait until remote device drives it and measure release time.
*
* \pre TIM1 is configured to 1 MHz, 60 mks period.
* \pre TIM1 counter is set to 0.
* \pre TIM1 CC1 is configured to input capture.
* \returns 0x80 if 1 was read
*/
static inline uint8_t read(void)
{
uint8_t tmp = 0;
uint8_t result = 0;
TIM1->CR1 |= TIM1_CR1_CEN;
OW_PORT->ODR |= OW_OUT;
for (;;)
{
tmp = TIM1->CNTRH;
if (TIM1->CNTRL >= READ_PULSE)
break;
}
OW_PORT->ODR &= ~OW_OUT;
for (;;)
{
tmp = TIM1->CNTRH;
if (TIM1->CNTRL >= READ_TIME)
break;
}
result = (OW_PORT->IDR & OW_IN) ? 0x80 : 0;
while (TIM1->CR1 & TIM1_CR1_CEN); // Wait until the end of time slot.
TIM1_ClearFlag(TIM1_FLAG_UPDATE);
return result;
}
/**
* 1-wire write 0 cycle (60 mks).
* Drive line low for the whole cycle.
*
* \pre TIM1 is configured to 1 MHz, 60 mks period.
* \pre TIM1 counter is set to 0.
*/
static inline void write_0(void)
{
TIM1->CR1 |= TIM1_CR1_CEN;
OW_PORT->ODR |= OW_OUT; // Drives line low.
while (TIM1->CR1 & TIM1_CR1_CEN);
OW_PORT->ODR &= ~OW_OUT; // Release line.
TIM1_ClearFlag(TIM1_FLAG_UPDATE);
}
/**
* @brief Configure TIM1 to to capture the internal clock source (LSI)
* @param None
* @retval None
*/
static void TIM1_Config(void)
{
TIM1_ICInit( TIM1_CHANNEL_1, TIM1_ICPOLARITY_FALLING, TIM1_ICSELECTION_DIRECTTI,
TIM1_ICPSC_DIV8, 0x0);
/* Enable TIM1 */
TIM1_Cmd(ENABLE);
/* Clear CC1 Flag*/
TIM1_ClearFlag(TIM1_FLAG_CC1);
/* wait a capture on CC1 */
while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
/* Get CCR1 value*/
ICValue1 = TIM1_GetCapture1();
TIM1_ClearFlag(TIM1_FLAG_CC1);
/* wait a capture on cc1 */
while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
/* Get CCR1 value*/
ICValue2 = TIM1_GetCapture1();
TIM1_ClearFlag(TIM1_FLAG_CC1);
}
/**
* 1-wire write 1 cycle (60 mks).
* Drive line low for ~5 mks, then drive it high.
*
* \pre TIM1 is configured to 1 MHz, 60 mks period.
* \pre TIM1 counter is set to 0.
*/
static inline void write_1(void)
{
uint8_t tmp;
TIM1->CR1 |= TIM1_CR1_CEN;
OW_PORT->ODR |= OW_OUT; // Drives line low.
while (TIM1->CR1 & TIM1_CR1_CEN)
{
tmp = TIM1->CNTRH;
if (TIM1->CNTRL >= WRITE1_TIME)
{
OW_PORT->ODR &= ~OW_OUT;
break;
}
}
while (TIM1->CR1 & TIM1_CR1_CEN); // Wait until the end of time slot.
TIM1_ClearFlag(TIM1_FLAG_UPDATE);
}
/**
* @brief Measure the LSI frequency using timer IC1 and update the calibration registers.
* @par Parameters:
* None
* @retval
* None
* @par Required preconditions:
* It is recommanded to use a timer clock frequency of at least 10MHz in order
* to obtain a better in the LSI frequency measurement.
*/
u32 LSIMeasurment(void)
{
u32 lsi_freq_hz = 0x0;
u32 fmaster = 0x0;
u16 ICValue1 = 0x0;
u16 ICValue2 = 0x0;
/* Get master frequency */
fmaster = CLK_GetClockFreq();
/* Enable the LSI measurement: LSI clock connected to timer Input Capture 1 */
AWU->CSR |= AWU_CSR_MSR;
#if defined (STM8S903) || defined (STM8S103)
/* Measure the LSI frequency with TIMER Input Capture 1 */
/* Capture only every 8 events!!! */
/* Enable capture of TI1 */
TIM1_ICInit(TIM1_CHANNEL_1, TIM1_ICPOLARITY_RISING, TIM1_ICSELECTION_DIRECTTI, TIM1_ICPSC_DIV8, 0);
/* Enable TIM1 */
TIM1_Cmd(ENABLE);
/* wait a capture on cc1 */
while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
/* Get CCR1 value*/
ICValue1 = TIM1_GetCapture1();
TIM1_ClearFlag(TIM1_FLAG_CC1);
/* wait a capture on cc1 */
while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
/* Get CCR1 value*/
ICValue2 = TIM1_GetCapture1();
TIM1_ClearFlag(TIM1_FLAG_CC1);
/* Disable IC1 input capture */
TIM1->CCER1 &= (u8)(~TIM1_CCER1_CC1E);
/* Disable timer2 */
TIM1_Cmd(DISABLE);
#else
/* Measure the LSI frequency with TIMER Input Capture 1 */
/* Capture only every 8 events!!! */
/* Enable capture of TI1 */
TIM3_ICInit(TIM3_CHANNEL_1, TIM3_ICPOLARITY_RISING, TIM3_ICSELECTION_DIRECTTI, TIM3_ICPSC_DIV8, 0);
/* Enable TIM3 */
TIM3_Cmd(ENABLE);
/* wait a capture on cc1 */
while ((TIM3->SR1 & TIM3_FLAG_CC1) != TIM3_FLAG_CC1);
/* Get CCR1 value*/
ICValue1 = TIM3_GetCapture1();
TIM3_ClearFlag(TIM3_FLAG_CC1);
/* wait a capture on cc1 */
while ((TIM3->SR1 & TIM3_FLAG_CC1) != TIM3_FLAG_CC1);
/* Get CCR1 value*/
ICValue2 = TIM3_GetCapture1();
TIM3_ClearFlag(TIM3_FLAG_CC1);
/* Disable IC1 input capture */
TIM3->CCER1 &= (u8)(~TIM3_CCER1_CC1E);
/* Disable timer3 */
TIM3_Cmd(DISABLE);
#endif
/* Compute LSI clock frequency */
lsi_freq_hz = (8 * fmaster) / (ICValue2 - ICValue1);
/* Disable the LSI measurement: LSI clock disconnected from timer Input Capture 1 */
AWU->CSR &= (u8)(~AWU_CSR_MSR);
return (lsi_freq_hz);
}
