diff options
Diffstat (limited to 'libmaple/adc.c')
| -rw-r--r-- | libmaple/adc.c | 171 |
1 files changed, 108 insertions, 63 deletions
diff --git a/libmaple/adc.c b/libmaple/adc.c index 3e6818c..73dce0a 100644 --- a/libmaple/adc.c +++ b/libmaple/adc.c @@ -23,85 +23,92 @@ *****************************************************************************/ /** - * @brief Analog to digital converter routines - */ - -#include "libmaple.h" -#include "rcc.h" -#include "adc.h" - -/* The ADC input clock is generated from PCLK2/APB2 divided by a prescaler - * and it must not exceed 14MHz. + * @file adc.c * - * ADC1 and ADC2 are clocked by APB2 - * - * 1) Power on by setting ADON in ADC_CR2 - * Conversion starts when ADON is set for a second time after some - * time t > t_stab. - * - * Up to 16 selected conversion must be selected in ADC_SQRx - * - * Single conversion mode: - * Set the ADON bit in the ADC_CR2 register - * Once the conversion is complete: - * Converted data is stored in ADC_DR - * EOC flag is set - * Interrupt is generated if EOCIE is set - * - * Calibration: - * Calibration is started by setting the CAL bit in the ADC_CR2 register. - * Once calibration is over, the CAL bit is reset by hardware and normal - * conversion can be performed. Calibrate at power-on. - * - * ALIGN in ADC_CR2 selects the alignment of data + * @brief Analog to digital converter routines * * IMPORTANT: maximum external impedance must be below 0.4kOhms for 1.5 * sample conversion time. * - * At 55.5 cycles/sample, the external input impedance < 50kOhms*/ - -void set_adc_smprx(adc_smp_rate smp_rate); + * At 55.5 cycles/sample, the external input impedance < 50kOhms. + * + * See STM32 manual RM0008 for how to calculate this. + */ -void adc_init(adc_smp_rate smp_rate) { - rcc_set_prescaler(RCC_PRESCALER_ADC, RCC_ADCPRE_PCLK_DIV_6); - rcc_clk_enable(RCC_ADC1); - rcc_reset_dev(RCC_ADC1); +#include "libmaple.h" +#include "rcc.h" +#include "adc.h" - ADC_CR1 = 0; - /* Software triggers conversions */ - ADC_CR2 = CR2_EXTSEL_SWSTART | CR2_EXTTRIG; - ADC_SQR1 = 0; +adc_dev adc1 = { + .regs = ADC1_BASE, + .clk_id = RCC_ADC1 +}; +const adc_dev *ADC1 = &adc1; - /* Set the sample conversion time. See note above for impedance - requirements. */ - adc_set_sample_rate(smp_rate); +adc_dev adc2 = { + .regs = ADC2_BASE, + .clk_id = RCC_ADC2 +}; +const adc_dev *ADC2 = &adc2; - /* Enable the ADC */ - CR2_ADON_BIT = 1; +#ifdef STM32_HIGH_DENSITY +adc_dev adc3 = { + .regs = ADC3_BASE, + .clk_id = RCC_ADC3 +}; +const adc_dev *ADC3 = &adc3; +#endif - /* Reset the calibration registers and then perform a reset */ - CR2_RSTCAL_BIT = 1; - while(CR2_RSTCAL_BIT) - ; - - CR2_CAL_BIT = 1; - while(CR2_CAL_BIT) - ; +/** + * @brief Initialize an ADC peripheral. + * + * Initializes the RCC clock line for the given peripheral, using ADC + * prescaler RCC_ADCPRE_PCLK_DIV_6. Resets ADC device registers. + * + * @param dev ADC peripheral to initialize + */ +void adc_init(const adc_dev *dev) { + rcc_set_prescaler(RCC_PRESCALER_ADC, RCC_ADCPRE_PCLK_DIV_6); + rcc_clk_enable(dev->clk_id); + rcc_reset_dev(dev->clk_id); } +/** + * @brief Set external event select for regular group + * @param dev ADC device + * @param event Event used to trigger the start of conversion. + * @see adc_extsel_event + */ +void adc_set_extsel(const adc_dev *dev, adc_extsel_event event) { + uint32 cr2 = dev->regs->CR2; + cr2 &= ~ADC_CR2_EXTSEL; + cr2 |= event; + dev->regs->CR2 = cr2; +} -void adc_disable(void) { - CR2_ADON_BIT = 0; +/** + * @brief Call a function on all ADC devices. + * @param fn Function to call on each ADC device. + */ +void adc_foreach(void (*fn)(const adc_dev*)) { + fn(ADC1); + fn(ADC2); +#ifdef STM32_HIGH_DENSITY + fn(ADC3); +#endif } -/* Turn the given sample rate into values for ADC_SMPRx. (Don't - * precompute in order to avoid wasting space). - * - * Don't call this during conversion! +/** + * @brief Turn the given sample rate into values for ADC_SMPRx. Don't + * call this during conversion. + * @param dev adc device + * @param smp_rate sample rate to set + * @see adc_smp_rate */ -void adc_set_sample_rate(adc_smp_rate smp_rate) { +void adc_set_sample_rate(const adc_dev *dev, adc_smp_rate smp_rate) { uint32 adc_smpr1_val = 0, adc_smpr2_val = 0; int i; + for (i = 0; i < 10; i++) { if (i < 8) { /* ADC_SMPR1 determines sample time for channels [10,17] */ @@ -110,6 +117,44 @@ void adc_set_sample_rate(adc_smp_rate smp_rate) { /* ADC_SMPR2 determines sample time for channels [0,9] */ adc_smpr2_val |= smp_rate << (i * 3); } - ADC_SMPR1 = adc_smpr1_val; - ADC_SMPR2 = adc_smpr2_val; + + dev->regs->SMPR1 = adc_smpr1_val; + dev->regs->SMPR2 = adc_smpr2_val; +} + +/** + * @brief Calibrate an ADC peripheral + * @param dev adc device + */ +void adc_calibrate(const adc_dev *dev) { + __io uint32 *rstcal_bit = bb_perip(&(dev->regs->CR2), 3); + __io uint32 *cal_bit = bb_perip(&(dev->regs->CR2), 2); + + *rstcal_bit = 1; + while (*rstcal_bit) + ; + + *cal_bit = 1; + while (*cal_bit) + ; +} + +/** + * @brief Perform a single synchronous software triggered conversion on a + * channel. + * @param dev ADC device to use for reading. + * @param channel channel to convert + * @return conversion result + */ +uint16 adc_read(const adc_dev *dev, uint8 channel) { + adc_reg_map *regs = dev->regs; + + adc_set_reg_seqlen(dev, 1); + + regs->SQR3 = channel; + regs->CR2 |= ADC_CR2_SWSTART; + while(!(regs->SR & ADC_SR_EOC)) + ; + + return (uint16)(regs->DR & ADC_DR_DATA); } |