F4: updates in adc.h and adc.c

[ag88]

• ADC1, ADC2, ADC3 fixup for invalid conversion from const errors

initially i'm running into some errors: invalid conversion from 'const adc_dev*' while using ADC1, ADC2, ADC3

 extern const adc_dev adc1;
 extern const adc_dev adc2;
 extern const adc_dev adc3;

 #define ADC1 (&adc1)
 #define ADC2 (&adc2)
 #define ADC3 (&adc3)

those errors are resolved by defining them as follows

 extern const adc_dev adc1;
 extern const adc_dev adc2;
 extern const adc_dev adc3;

 #define ADC1 ((adc_dev*) &adc1)
 #define ADC2 ((adc_dev*) &adc2)
 #define ADC3 ((adc_dev*) &adc3)

• add adc_prescaler this is modeled after the same function in the F1 core, the macro symbols are same as well. this would make it more 'compatible' for those writing codes that may possibly be used in both F1 and F4 sets.

adc.h

/**
 * @brief STM32F1/F4 ADC prescalers, as divisors of PCLK2.
 */
typedef enum adc_prescaler {
    /** PCLK2 divided by 2 */
    ADC_PRE_PCLK2_DIV_2 = 0,
    /** PCLK2 divided by 4 */
    ADC_PRE_PCLK2_DIV_4 = 1,
    /** PCLK2 divided by 6 */
    ADC_PRE_PCLK2_DIV_6 = 2,
    /** PCLK2 divided by 8 */
    ADC_PRE_PCLK2_DIV_8 = 3,
} adc_prescaler;

void adc_set_prescaler(adc_prescaler pre);

adc.c

/*
 *  @param pre, setup the ADC prescaler to one of PCLK /2, /4, /6, /8
 *         the templates per adc_prescaler enum
 */
void adc_set_prescaler(adc_prescaler pre) {

    ADC_COMMON->CCR &= ~ ADC_CCR_ADCPRE;
    ADC_COMMON->CCR |= ((pre & 3U) << ADC_CCR_ADCPRE_SHIFT);
}

• add static inline void adc_awd_disable()

adc.h

static inline void adc_awd_disable(const adc_dev * dev)
{
    dev->regs->CR1 &= ~ADC_CR1_AWDEN;
}

• add ADC overrun interrupt support, add missing adc_awd_enable_irq() when setting up adc_awd irq handler

adc.h

//Added by bubulindo - Interrupt ID's for ADC
typedef enum {
    ADC_EOC,     // End Of Conversion interrupt.
    ADC_AWD ,    // Analog WatchDog interrupt
    ADC_JEOC,    // Injected End Of Conversion interrupt.
    ADC_OVR,     // overrun interrupt
    ADC_LAST_IRQ_ID
} adc_irq_id;

void adc_ovr_enable_irq(const adc_dev* dev);

adc.c

void adc_ovr_enable_irq(const adc_dev* dev)
{
    dev->regs->CR1 |= ADC_CR1_OVRIE;
    //nvic_irq_enable(NVIC_ADC_1_2_3);
}

void adc_attach_interrupt(const adc_dev *dev,
                            adc_irq_id irq_id,
                            voidFuncPtr handler)
{
    if (irq_id<ADC_LAST_IRQ_ID)
    {
        (*(dev->handler_p))[irq_id] = handler;
        if(irq_id == ADC_EOC)
            adc_enable_irq(dev);
        else if (irq_id == ADC_AWD)
            adc_awd_enable_irq(dev);
        else if (irq_id == ADC_OVR)
            adc_ovr_enable_irq(dev);
    }
}

/*
    ADC IRQ handler.
    added by bubulindo
*/
void adc_irq_handler(const adc_dev * dev)
{
    //End Of Conversion
    if (dev->regs->SR & ADC_SR_EOC) {
        dev->regs->SR = ~ADC_SR_EOC;
        voidFuncPtr handler = (*(dev->handler_p))[ADC_EOC];
        if (handler) {
            handler();
        }
    }
    //Injected End Of Conversion
    if (dev->regs->SR & ADC_SR_JEOC) {
        dev->regs->SR = ~ADC_SR_JEOC;
        voidFuncPtr handler = (*(dev->handler_p))[ADC_JEOC];
        if (handler) {
            handler();
        }
    }
    //Analog Watchdog
    if (dev->regs->SR & ADC_SR_AWD) {
        dev->regs->SR = ~ADC_SR_AWD;
        voidFuncPtr handler = (*(dev->handler_p))[ADC_AWD];
        if (handler) {
            handler();
        }
    }

    //ADC overrun interrupt
    if (dev->regs->SR & ADC_SR_OVR) {
        dev->regs->SR = ~ADC_SR_OVR;
        voidFuncPtr handler = (*(dev->handler_p))[ADC_OVR];
        if (handler) {
            handler();
        }
    }

}

[ag88]

partly discussed in issue thread in steve's core https://github.com/stevstrong/Arduino_STM32/issues/41

[stevstrong]

Do you have a simple sketch to test the new functions?

[ag88]

working on it (the example/test sketch), check back later ;)

[ag88]

i've added a test sketch in STM32F4/libraries/STM32F4_ADC/examples/PR784F4AdcTest/

as i worked the test sketch, i actually found a bug in my code and fixed it that fix is commited here as well. as the tests include a few functionality, e.g. setting adc_prescaler, setting up awd and overrun interrupts. the tests evolved into a little app on its own, i made the sketch read the temperature sensor and use the analog watch dog to test the upper threshold which triggers when a higher temperature is detected. it responds to a single character command 'w' which toggles the watch dog on / off.

i observed something interesting during the tests, EOC may not be set if the awd triggers. i end up adding some codes, which checks for awd triggers and if the awd is triggered, i disable AWD and read the temperature sensor again. hence, the adc_awd_disable() function becomes handy.

to test adc overrun, you'd need to uncomment several lines of codes in loop(). the overruns occurs by triggering conversion ADC1->regs->CR2 |= ADC_CR2_SWSTART but not reading the ADC data register. i've added in addition a readme.md file which i hope may be helpful.

[stevstrong]

Seems to work ok, so I will merge it.