libopencm3/lib/stm32/f4/adc.c

/** @defgroup STM32F4xx_adc_file ADC

@ingroup STM32F4xx

@brief <b>libopencm3 STM32F4xx Analog to Digital Converters</b>

@author @htmlonly &copy; @endhtmlonly 2012
Ken Sarkies <ksarkies@internode.on.net>

@date 30 August 2012

This library supports the A/D Converter Control System in the STM32 series
of ARM Cortex Microcontrollers by ST Microelectronics.

Devices can have up to three A/D converters each with their own set of
registers.  However all the A/D converters share a common clock which is
prescaled from the APB2 clock by default by a minimum factor of 2 to a maximum
of 8. The ADC resolution can be set to 12, 10, 8 or 6 bits.

Each A/D converter has up to 19 channels:
@li On ADC1 the analog channels 16 is internally connected to the temperature
sensor, channel 17 to V<sub>REFINT</sub>, and channel 18 to V<sub>BATT</sub>.
@li On ADC2 and ADC3 the analog channels 16 - 18 are not used.

The conversions can occur as a one-off conversion whereby the process stops
once conversion is complete. The conversions can also be continuous wherein a
new conversion starts immediately the previous conversion has ended.

Conversion can occur as a single channel conversion or a scan of a group of
channels in either continuous or one-off mode. If more than one channel is
converted in a scan group, DMA must be used to transfer the data as there is
only one result register available. An interrupt can be set to occur at the end
of conversion, which occurs after all channels have been scanned.

A discontinuous mode allows a subgroup of group of a channels to be converted
in bursts of a given length.

Injected conversions allow a second group of channels to be converted
separately from the regular group. An interrupt can be set to occur at the end
of conversion, which occurs after all channels have been scanned.

@section adc_f4_api_ex Basic ADC Handling API.

Example 1: Simple single channel conversion polled. Enable the peripheral clock
and ADC, reset ADC and set the prescaler divider. Set multiple mode to
independent.

@code
gpio_mode_setup(GPIOA, GPIO_MODE_ANALOG, GPIO_PUPD_NONE, GPIO1);
rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_ADC1EN);
adc_set_clk_prescale(RCC_CFGR_ADCPRE_BY2);
adc_disable_scan_mode(ADC1);
adc_set_single_conversion_mode(ADC1);
adc_set_sample_time(ADC1, ADC_CHANNEL0, ADC_SMPR1_SMP_1DOT5CYC);
uint8_t channels[] = ADC_CHANNEL0;
adc_set_regular_sequence(ADC1, 1, channels);
adc_set_multi_mode(ADC_CCR_MULTI_INDEPENDENT);
adc_power_on(ADC1);
adc_start_conversion_regular(ADC1);
while (! adc_eoc(ADC1));
reg16 = adc_read_regular(ADC1);
@endcode

LGPL License Terms @ref lgpl_license
 */
/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2012 Ken Sarkies <ksarkies@internode.on.net>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopencm3/stm32/f4/adc.h>

/**@{*/

/*---------------------------------------------------------------------------*/
/** @brief ADC Off

Turn off the ADC to reduce power consumption to a few microamps.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_off(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_ADON;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Analog Watchdog for Regular Conversions

The analog watchdog allows the monitoring of an analog signal between two
threshold levels. The thresholds must be preset. Comparison is done before data
alignment takes place, so the thresholds are left-aligned.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_analog_watchdog_regular(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_AWDEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Analog Watchdog for Regular Conversions

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_analog_watchdog_regular(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_AWDEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Analog Watchdog for Injected Conversions

The analog watchdog allows the monitoring of an analog signal between two
threshold levels. The thresholds must be preset. Comparison is done before data
alignment takes place, so the thresholds are left-aligned.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_analog_watchdog_injected(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_JAWDEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Analog Watchdog for Injected Conversions

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_analog_watchdog_injected(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_JAWDEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Discontinuous Mode for Regular Conversions

In this mode the ADC converts, on each trigger, a subgroup of up to 8 of the
defined regular channel group. The subgroup is defined by the number of
consecutive channels to be converted. After a subgroup has been converted
the next trigger will start conversion of the immediately following subgroup
of the same length or until the whole group has all been converted. When the
the whole group has been converted, the next trigger will restart conversion
of the subgroup at the beginning of the whole group.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] length Unsigned int8. Number of channels in the group @ref
adc_cr1_discnum
*/

void adc_enable_discontinuous_mode_regular(uint32_t adc, uint8_t length)
{
	if ((length-1) > 7) {
		return;
	}
	ADC_CR1(adc) |= ADC_CR1_DISCEN;
	ADC_CR1(adc) |= ((length-1) << ADC_CR1_DISCNUM_SHIFT);
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Discontinuous Mode for Regular Conversions

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_discontinuous_mode_regular(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_DISCEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Discontinuous Mode for Injected Conversions

In this mode the ADC converts sequentially one channel of the defined group of
injected channels, cycling back to the first channel in the group once the
entire group has been converted.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_discontinuous_mode_injected(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_JDISCEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Discontinuous Mode for Injected Conversions

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_discontinuous_mode_injected(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_JDISCEN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Automatic Injected Conversions

The ADC converts a defined injected group of channels immediately after the
regular channels have been converted. The external trigger on the injected
channels is disabled as required.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_automatic_injected_group_conversion(uint32_t adc)
{
	adc_disable_external_trigger_injected(adc);
	ADC_CR1(adc) |= ADC_CR1_JAUTO;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Automatic Injected Conversions

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_automatic_injected_group_conversion(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_JAUTO;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Analog Watchdog for All Regular and/or Injected Channels

The analog watchdog allows the monitoring of an analog signal between two
threshold levels. The thresholds must be preset. Comparison is done before data
alignment takes place, so the thresholds are left-aligned.

@note The analog watchdog must be enabled for either or both of the regular or
injected channels. If neither are enabled, the analog watchdog feature will be
disabled.
@ref adc_enable_analog_watchdog_injected, @ref
adc_enable_analog_watchdog_regular.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_analog_watchdog_on_all_channels(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_AWDSGL;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Analog Watchdog for a Selected Channel

The analog watchdog allows the monitoring of an analog signal between two
threshold levels. The thresholds must be preset. Comparison is done before data
alignment takes place, so the thresholds are left-aligned.

@note The analog watchdog must be enabled for either or both of the regular or
injected channels. If neither are enabled, the analog watchdog feature will be
disabled. If both are enabled, the same channel number is monitored.
@ref adc_enable_analog_watchdog_injected, @ref
adc_enable_analog_watchdog_regular.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] channel Unsigned int8. ADC channel number @ref adc_watchdog_channel
*/

void adc_enable_analog_watchdog_on_selected_channel(uint32_t adc,
						    uint8_t channel)
{
	uint32_t reg32;

	reg32 = (ADC_CR1(adc) & ~ADC_CR1_AWDCH_MASK); /* Clear bits [4:0]. */
	if (channel < 18) {
		reg32 |= channel;
	}
	ADC_CR1(adc) = reg32;
	ADC_CR1(adc) |= ADC_CR1_AWDSGL;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Scan Mode

In this mode a conversion consists of a scan of the predefined set of channels,
regular and injected, each channel conversion immediately following the
previous one. It can use single, continuous or discontinuous mode.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_scan_mode(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_SCAN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Scan Mode

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_scan_mode(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_SCAN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Injected End-Of-Conversion Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_eoc_interrupt_injected(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_JEOCIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Injected End-Of-Conversion Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_eoc_interrupt_injected(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_JEOCIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Analog Watchdog Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_awd_interrupt(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_AWDIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Analog Watchdog Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_awd_interrupt(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_AWDIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Regular End-Of-Conversion Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_eoc_interrupt(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_EOCIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable Regular End-Of-Conversion Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_eoc_interrupt(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_EOCIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Software Triggered Conversion on Regular Channels

This starts conversion on a set of defined regular channels. It is cleared by
hardware once conversion starts.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_start_conversion_regular(uint32_t adc)
{
	/* Start conversion on regular channels. */
	ADC_CR2(adc) |= ADC_CR2_SWSTART;

	/* Wait until the ADC starts the conversion. */
	while (ADC_CR2(adc) & ADC_CR2_SWSTART);
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Software Triggered Conversion on Injected Channels

This starts conversion on a set of defined injected channels. It is cleared by
hardware once conversion starts.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_start_conversion_injected(uint32_t adc)
{
	/* Start conversion on injected channels. */
	ADC_CR2(adc) |= ADC_CR2_JSWSTART;

	/* Wait until the ADC starts the conversion. */
	while (ADC_CR2(adc) & ADC_CR2_JSWSTART);
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set the Data as Left Aligned

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_left_aligned(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_ALIGN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set the Data as Right Aligned

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_right_aligned(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_ALIGN;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable DMA Transfers

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_dma(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_DMA;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable DMA Transfers

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_dma(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_DMA;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Continuous Conversion Mode

In this mode the ADC starts a new conversion of a single channel or a channel
group immediately following completion of the previous channel group conversion.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_continuous_conversion_mode(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_CONT;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable Single Conversion Mode

In this mode the ADC performs a conversion of one channel or a channel group
and stops.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_single_conversion_mode(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_CONT;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set the Sample Time for a Single Channel

The sampling time can be selected in ADC clock cycles from 1.5 to 239.5.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] channel Unsigned int8. ADC Channel integer 0..18 or from @ref
adc_channel
@param[in] time Unsigned int8. Sampling time selection from @ref adc_sample_rg
*/

void adc_set_sample_time(uint32_t adc, uint8_t channel, uint8_t time)
{
	uint32_t reg32;

	if (channel < 10) {
		reg32 = ADC_SMPR2(adc);
		reg32 &= ~(0x7 << (channel * 3));
		reg32 |= (time << (channel * 3));
		ADC_SMPR2(adc) = reg32;
	} else {
		reg32 = ADC_SMPR1(adc);
		reg32 &= ~(0x7 << ((channel - 10) * 3));
		reg32 |= (time << ((channel - 10) * 3));
		ADC_SMPR1(adc) = reg32;
	}
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set the Sample Time for All Channels

The sampling time can be selected in ADC clock cycles from 1.5 to 239.5, same
for all channels.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] time Unsigned int8. Sampling time selection from @ref adc_sample_rg
*/

void adc_set_sample_time_on_all_channels(uint32_t adc, uint8_t time)
{
	uint8_t i;
	uint32_t reg32 = 0;

	for (i = 0; i <= 9; i++) {
		reg32 |= (time << (i * 3));
	}
	ADC_SMPR2(adc) = reg32;

	for (i = 10; i <= 17; i++) {
		reg32 |= (time << ((i - 10) * 3));
	}
	ADC_SMPR1(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Analog Watchdog Upper Threshold

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] threshold Unsigned int8. Upper threshold value
*/

void adc_set_watchdog_high_threshold(uint32_t adc, uint16_t threshold)
{
	uint32_t reg32 = 0;

	reg32 = (uint32_t)threshold;
	reg32 &= ~0xfffff000; /* Clear all bits above 11. */
	ADC_HTR(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Analog Watchdog Lower Threshold

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] threshold Unsigned int8. Lower threshold value
*/

void adc_set_watchdog_low_threshold(uint32_t adc, uint16_t threshold)
{
	uint32_t reg32 = 0;

	reg32 = (uint32_t)threshold;
	reg32 &= ~0xfffff000; /* Clear all bits above 11. */
	ADC_LTR(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set a Regular Channel Conversion Sequence

Define a sequence of channels to be converted as a regular group with a length
from 1 to 16 channels. If this is called during conversion, the current
conversion is reset and conversion begins again with the newly defined group.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] length Unsigned int8. Number of channels in the group.
@param[in] channel Unsigned int8[]. Set of channels in sequence, integers 0..18.
*/

void adc_set_regular_sequence(uint32_t adc, uint8_t length, uint8_t channel[])
{
	uint32_t reg32_1 = 0, reg32_2 = 0, reg32_3 = 0;
	uint8_t i = 0;

	/* Maximum sequence length is 16 channels. */
	if (length > 16) {
		return;
	}

	for (i = 1; i <= length; i++) {
		if (i <= 6) {
			reg32_3 |= (channel[i - 1] << ((i - 1) * 5));
		}
		if ((i > 6) & (i <= 12)) {
			reg32_2 |= (channel[i - 1] << ((i - 6 - 1) * 5));
		}
		if ((i > 12) & (i <= 16)) {
			reg32_1 |= (channel[i - 1] << ((i - 12 - 1) * 5));
		}
	}
	reg32_1 |= ((length - 1) << ADC_SQR1_L_LSB);

	ADC_SQR1(adc) = reg32_1;
	ADC_SQR2(adc) = reg32_2;
	ADC_SQR3(adc) = reg32_3;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set an Injected Channel Conversion Sequence

Defines a sequence of channels to be converted as an injected group with a
length from 1 to 4 channels. If this is called during conversion, the current
conversion is reset and conversion begins again with the newly defined group.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] length Unsigned int8. Number of channels in the group.
@param[in] channel Unsigned int8[]. Set of channels in sequence, integers 0..18
*/

void adc_set_injected_sequence(uint32_t adc, uint8_t length, uint8_t channel[])
{
	uint32_t reg32 = 0;
	uint8_t i = 0;

	/* Maximum sequence length is 4 channels. */
	if ((length-1) > 3) {
		return;
	}

	for (i = 1; i <= length; i++) {
		reg32 |= (channel[4 - i] << ((4 - i) * 5));
	}

	reg32 |= ((length - 1) << ADC_JSQR_JL_LSB);

	ADC_JSQR(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Read the End-of-Conversion Flag

This flag is set after all channels of a regular or injected group have been
converted.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns bool. End of conversion flag.
*/

bool adc_eoc(uint32_t adc)
{
	return (ADC_SR(adc) & ADC_SR_EOC) != 0;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Read the End-of-Conversion Flag for Injected Conversion

This flag is set after all channels of an injected group have been converted.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns bool. End of conversion flag.
*/

bool adc_eoc_injected(uint32_t adc)
{
	return (ADC_SR(adc) & ADC_SR_JEOC) != 0;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Read from the Regular Conversion Result Register

The result read back is 12 bits, right or left aligned within the first 16 bits.
For ADC1 only, the higher 16 bits will hold the result from ADC2 if
an appropriate dual mode has been set @see adc_set_dual_mode.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns Unsigned int32 conversion result.
*/

uint32_t adc_read_regular(uint32_t adc)
{
	return ADC_DR(adc);
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Read from an Injected Conversion Result Register

The result read back from the selected injected result register (one of four)
is 12 bits, right or left aligned within the first 16 bits. The result can have
a negative value if the injected channel offset has been set @see
adc_set_injected_offset.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] reg Unsigned int8. Register number (1 ... 4).
@returns Unsigned int32 conversion result.
*/

uint32_t adc_read_injected(uint32_t adc, uint8_t reg)
{
	switch (reg) {
	case 1:
		return ADC_JDR1(adc);
	case 2:
		return ADC_JDR2(adc);
	case 3:
		return ADC_JDR3(adc);
	case 4:
		return ADC_JDR4(adc);
	}
	return 0;
}

/*----------------------------------------------------------------------------*/
/** @brief ADC Set the Injected Channel Data Offset

This value is subtracted from the injected channel results after conversion is
complete, and can result in negative results. A separate value can be specified
for each injected data register.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] reg Unsigned int8. Register number (1 ... 4).
@param[in] offset Unsigned int32.
*/

void adc_set_injected_offset(uint32_t adc, uint8_t reg, uint32_t offset)
{
	switch (reg) {
	case 1:
		ADC_JOFR1(adc) = offset;
		break;
	case 2:
		ADC_JOFR2(adc) = offset;
		break;
	case 3:
		ADC_JOFR3(adc) = offset;
		break;
	case 4:
		ADC_JOFR4(adc) = offset;
		break;
	}
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Power On

If the ADC is in power-down mode then it is powered up. The application needs
to wait a time of about 3 microseconds for stabilization before using the ADC.
If the ADC is already on this function call will have no effect.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_power_on(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_ADON;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Clock Prescale

The ADC clock taken from the APB2 clock can be scaled down by 2, 4, 6 or 8.

@param[in] prescale Unsigned int32. Prescale value for ADC Clock @ref
adc_ccr_adcpre
*/

void adc_set_clk_prescale(uint32_t prescale)
{
	uint32_t reg32 = ((ADC_CCR & ~ADC_CCR_ADCPRE_MASK) | prescale);
	ADC_CCR = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Dual/Triple Mode

The multiple mode uses ADC1 as master, ADC2 and optionally ADC3 in a slave
arrangement. This setting is applied to ADC1 only.

The various modes possible are described in the reference manual.

@param[in] mode Unsigned int32. Multiple mode selection from @ref adc_multi_mode
*/

void adc_set_multi_mode(uint32_t mode)
{
	ADC_CCR |= mode;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable an External Trigger for Regular Channels

This enables an external trigger for set of defined regular channels, and sets
the polarity of the trigger event: rising or falling edge or both. Note that if
the trigger polarity is zero, triggering is disabled.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] trigger Unsigned int32. Trigger identifier @ref adc_trigger_regular
@param[in] polarity Unsigned int32. Trigger polarity @ref
adc_trigger_polarity_regular
*/

void adc_enable_external_trigger_regular(uint32_t adc, uint32_t trigger,
					 uint32_t polarity)
{
	uint32_t reg32 = ADC_CR2(adc);

	reg32 &= ~(ADC_CR2_EXTSEL_MASK | ADC_CR2_EXTEN_MASK);
	reg32 |= (trigger | polarity);
	ADC_CR2(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable an External Trigger for Regular Channels

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_external_trigger_regular(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_EXTEN_MASK;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable an External Trigger for Injected Channels

This enables an external trigger for set of defined injected channels, and sets
the polarity of the trigger event: rising or falling edge or both.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] trigger Unsigned int8. Trigger identifier @ref adc_trigger_injected
@param[in] polarity Unsigned int32. Trigger polarity @ref
adc_trigger_polarity_injected
*/

void adc_enable_external_trigger_injected(uint32_t adc, uint32_t trigger,
					  uint32_t polarity)
{
	uint32_t reg32 = ADC_CR2(adc);

	reg32 &= ~(ADC_CR2_JEXTSEL_MASK | ADC_CR2_JEXTEN_MASK);
	reg32 |= (trigger | polarity);
	ADC_CR2(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable an External Trigger for Injected Channels

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_external_trigger_injected(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_JEXTEN_MASK;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set Resolution

ADC Resolution can be reduced from 12 bits to 10, 8 or 6 bits for a
corresponding reduction in conversion time (resolution + 3 ADC clock cycles).

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@param[in] resolution Unsigned int8. Resolution value @ref adc_cr1_res
*/

void adc_set_resolution(uint32_t adc, uint16_t resolution)
{
	uint32_t reg32 = ADC_CR1(adc);

	reg32 &= ~ADC_CR1_RES_MASK;
	reg32 |= resolution;
	ADC_CR1(adc) = reg32;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable the Overrun Interrupt

The overrun interrupt is generated when data is not read from a result register
before the next conversion is written. If DMA is enabled, all transfers are
terminated and any conversion sequence is aborted.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_overrun_interrupt(uint32_t adc)
{
	ADC_CR1(adc) |= ADC_CR1_OVRIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable the Overrun Interrupt

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_overrun_interrupt(uint32_t adc)
{
	ADC_CR1(adc) &= ~ADC_CR1_OVRIE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Read the Overrun Flag

The overrun flag is set when data is not read from a result register before the
next conversion is written. If DMA is enabled, all transfers are terminated and
any conversion sequence is aborted.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns Unsigned int32 conversion result.
*/

bool adc_get_overrun_flag(uint32_t adc)
{
	return ADC_SR(adc) & ADC_SR_OVR;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Clear Overrun Flags

The overrun flag is cleared. Note that if an overrun occurs, DMA is terminated.
The flag must be cleared and the DMA stream and ADC reinitialised to resume
conversions (see the reference manual).

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns Unsigned int32 conversion result.
*/

void adc_clear_overrun_flag(uint32_t adc)
{
/* need to write zero to clear this */
	ADC_SR(adc) &= ~ADC_SR_OVR;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable an EOC for Each Conversion

The EOC is set after each conversion in a sequence rather than at the end of the
sequence. Overrun detection is enabled only if DMA is enabled.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_eoc_after_each(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_EOCS;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable the EOC for Each Conversion

The EOC is set at the end of each sequence rather than after each conversion in
the sequence. Overrun detection is enabled always.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_eoc_after_group(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_EOCS;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set DMA to Continue

This must be set to allow DMA to continue to operate after the last conversion
in the DMA sequence. This allows DMA to be used in continuous circular mode.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_dma_continue(uint32_t adc)
{
	ADC_CR2(adc) |= ADC_CR2_DDS;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Set DMA to Terminate

This must be set to allow DMA to terminate after the last conversion in the DMA
sequence. This can avoid overrun errors.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_set_dma_terminate(uint32_t adc)
{
	ADC_CR2(adc) &= ~ADC_CR2_DDS;
}
/*---------------------------------------------------------------------------*/
/** @brief ADC Read the Analog Watchdog Flag

This flag is set when the converted voltage crosses the high or low thresholds.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
@returns bool. AWD flag.
*/

bool adc_awd(uint32_t adc)
{
	return ADC_SR(adc) & ADC_SR_AWD;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Enable The Temperature Sensor

This enables both the sensor and the reference voltage measurements on channels
16 and 17. These are only available on ADC1 channel 16 and 17 respectively.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_enable_temperature_sensor()
{
	ADC_CCR |= ADC_CCR_TSVREFE;
}

/*---------------------------------------------------------------------------*/
/** @brief ADC Disable The Temperature Sensor

Disabling this will reduce power consumption from the sensor and the reference
voltage measurements.

@param[in] adc Unsigned int32. ADC block register address base @ref adc_reg_base
*/

void adc_disable_temperature_sensor()
{
	ADC_CCR &= ~ADC_CCR_TSVREFE;
}

/*---------------------------------------------------------------------------*/

/**@}*/