Overview

This section describes the programming interface of the AFE Peripheral driver. The AFE peripheral driver provides functions to initialize AFE module and channels, conversion triggering, and result reading.

Channel configuration structures

The driver uses instances of the channel configuration structures to configuration and initialization AFE channel. This structure holds the settings of the AFE measurement channel. The settings include AFE hardware/software triggering, AFE continuous/Single conversion mode, AFE phase delay compensation, AFE channel mode, AFE channel analog gain, AFE channel oversampling ration, and AFE channel interrupt or DMA function. The AFE channel mode selects whether the bypass mode is enabled or disabled and the external clock selection.

User configuration structures

The AFE driver uses instances of the user configuration structure afe_user_config_t for the AFE driver configuration. This structure holds the configuration which is common for all AFE channels. The settings include AFE low power mode, AFE result format, AFE clock divider mode, AFE clock source mode, and AFE start up delay of modulators.

Initialization

To initialize the AFE driver, call the AFE_DRV_Init() function and pass the instance number of the AFE peripheral and a pointer to the user configuration structure. For a typical use case, call the AFE_DRV_StructInitUserConfigDefault() function which populates the structure.
Then, call the AFE_DRV_ChnInit function and pass the instance number, channel number and a pointer to the channel configuration structure. For a typical use case, call the AFE_DRV_StructInitChnConfigDefault() function which populates the structure.
The start up value can be set by the AFE_DRV_SetStartUpVal20us() function call or by filling the startupCnt parameter of the AfeChnConfig structure.
If the phase delay values are configured, call the AFE_DRV_AssertDelayOk() function and pass the instance number.
Finally, call the AFE_DRV_Enable() function and pass the instance number and a true boolean parameter. Ensure that the clock and VREF are configured properly before configuring the AFE. For more information, see a VREF and documentation for the KSDK Clock Manager.

typedef struct AfeUserConfig
{
    bool lowPowerEnable;  

This is an example of a typical AFE configuration. The afe_user_config_t instantiation is configured in the normal mode (low power mode disabled), result format is justified to the right, clock divider is selected 2 and a first clock source is selected (see the microcontroller documentation for information about these selections). The afe_chn_config_t instantiation is configured in the normal mode (no bypass), a continuous conversion, a zero delay, no interrupt or DMA request, the software trigger enabled, and the PGA disabled and the OSR is 2048.

This is an example code to set up a user and a channel AFE configuration instantiation:

afe_user_config_t afeConfig;
afeConfig.clkDividerMode = kAfeClkDividerInputOf2;
afeConfig.clkSrcMode = kAfeClkSrcClk1;
afeConfig.lowPowerEnable = false;
afeConfig.resultFormat = kAfeResultFormatRight;
afeTestStruct.startupCnt = 80; // startupCnt = (Clk_freq/Clk_div)*20e-6    
afe_chn_config_t afeChnConfig;
afeChnConfig.chnMode = kAfeNormal;
afeChnConfig.continuousConvEnable = true;
afeChnConfig.delay = 0;
afeChnConfig.chnEvent = kAfeNoneReq;
afeChnConfig.hwTriggerEnable = false;
afeChnConfig.pgaGainSel = kAfePgaDisable;
afeChnConfig.decimOSR = kAfeDecimOsrOf2048;

This example shows how to call the AFE_DRV_Init() given the user configuration structure and the AFE instance 0.

uint32_t afeInstance = 0;

UART_DRV_Init(afeInstance, &afeConfig);

This example shows how to call the AFE_DRV_ChnInit() given the channel configuration structure and the AFE channel 0 and 1.

uint32_t afeChannel0 = 0;
uint32_t afeChannel1 = 1;
AFE_DRV_ChnInit(afeInstance, afeChannel0, &afeChnConfig); // Configure AFE channel 0
AFE_DRV_ChnInit(afeInstance, afeChannel1, &afeChnConfig); // Configure AFE channel 1

The last part of the initialization contains the start up count setting, delay values confirmation, and the AFE module enabling.

AFE_DRV_AssertDelayOk(afeInstance); // Assert delay for all channels simultaneously

AFE_DRV_Enable(afeInstance, true); // Enable all configured channels

Measuring

The driver contains functions for software triggering, a channel delay after trigger setting, a result (raw or converted to right justified), reading and waiting functions.

If the software triggering is enabled (hwTriggerEnable parameter in afe_chn_config is a false value), call the AFE_DRV_SoftTriggerConv() function to start conversion. In this example, the channel 0 and channel 1 are triggered simultaneously. After the conversion is completed, the results are read.

int32_t res0,res1;
AFE_DRV_SoftTriggerConv(afeInstance, CHN_TRIG_MASK(0) | CHN_TRIG_MASK(1));
while(1)
{
    AFE_DRV_WaitConvDone(afeInstance, 0);
    AFE_DRV_WaitConvDone(afeInstance, 1);
    res0 = AFE_DRV_GetChnConvValue(afeInstance, 0);
    res1 = AFE_DRV_GetChnConvValue(afeInstance, 1);
}

If the hardware triggering is enabled (hwTriggerEnable parameter in afe_chn_config is a true value), the AFE_DRV_SoftTriggerConv() function isn't called. The rest of the code is the same.

If the continuous conversion isn't allowed (continuousConvEnable parameter in afe_chn_config is a false value), call the AFE_DRV_SoftTriggerConv() function (in the software trigger case) in the main loop to trigger the next conversion.

Data Structures
struct	afe_chn_config_t
	Defines the structure to initialize the AFE channel. More...

struct	afe_user_config_t
	Defines the structure to initialize the AFE module. More...

struct	afe_delay_config_t
	Defines the structure to configure phase delay of each AFE channel. More...

Enumerations
enum	afe_pga_state_t { kAfePgaDisable = 0U, kAfePgaGain1 = 1U, kAfePgaGain2 = 2U, kAfePgaGain4 = 3U, kAfePgaGain8 = 4U, kAfePgaGain16 = 5U, kAfePgaGain32 = 6U }
	Defines the PGA's values. More...

enum	afe_chn_mode_t { kAfeNormal = 0, kAfeBypassExternCltPosEdge = 1, kAfeBypassExternClkNegEdge = 2, kAfeBypassInternClkPosEdge = 3, kAfeBypassInternClkNegEdge = 4 }
	Defines the channel's modes. More...

enum	afe_chn_event_t { kAfeNoneReq = 0, kAfeIntReq = 1, kAfeDmaReq = 2 }
	Defines the channel's event requests. More...

enum	afe_flag_t { kAfeOverflowFlag = 0U, kAfeReadyFlag = 1U, kAfeConvCompleteFlag = 2U }
	Defines the type of event flags. More...

Functions
afe_status_t	AFE_DRV_StructInitUserConfigDefault (afe_user_config_t *userConfigPtr)
	Fills the user configure structure. More...

afe_status_t	AFE_DRV_StructInitChnConfigDefault (afe_chn_config_t *chnConfigPtr)
	Fills the channel configuration structure. More...

afe_status_t	AFE_DRV_Init (uint32_t instance, afe_user_config_t *userConfigPtr)
	Initializes the AFE module. More...

afe_status_t	AFE_DRV_ChnInit (uint32_t instance, uint32_t chn, afe_chn_config_t *chnConfigPtr)
	Initializes the selected AFE channel. More...

void	AFE_DRV_Enable (uint32_t instance, bool enable)
	Enables/disables all configured AFE channels. More...

void	AFE_DRV_WaitConvDone (uint32_t instance, uint32_t chn)
	Waits until the last conversion is complete. More...

void	AFE_DRV_WaitChnReady (uint32_t instance, uint32_t chn)
	Waits until the channel is ready for conversion. More...

void	AFE_DRV_SoftTriggerConv (uint32_t instance, uint32_t chnMask)
	Triggers the AFE conversion by software. More...

bool	AFE_DRV_GetChnFlag (uint32_t instance, uint32_t chn, afe_flag_t flag)
	Gets the flag for channel's events. More...

uint32_t	AFE_DRV_GetChnConvValRaw (uint32_t instance, uint32_t chn)
	Reads the conversion value in a raw form. More...

int32_t	AFE_DRV_GetChnConvVal (uint32_t instance, uint32_t chn)
	Reads the conversion value in 2's complement form. More...

void	AFE_DRV_Deinit (uint32_t instance)
	De-initializes the AFE module. More...

void	AFE_DRV_ChnDeinit (uint32_t instance, uint32_t chn)
	De-initializes the selected AFE channel. More...

void	AFE_DRV_AssertDelayOk (uint32_t instance)
	Asserts the phase delay setting. More...

void	AFE_DRV_SetPhaseDelays (uint32_t instance, afe_delay_config_t *delayConfigPtr)
	Sets phase delays. More...

Variables
AFE_Type *const	g_afeBase []
	Table of base addresses for AFE instances. More...

const IRQn_Type	g_afeIrqId []
	Table to save AFE IRQ enumeration numbers defined in CMSIS header file. More...

Data Structure Documentation

struct afe_chn_config_t

This structure keeps the configuration for the AFE channel.

Data Fields
bool	hwTriggerEnable
	Enable triggering by hardware.

bool	continuousConvEnable
	Enable continuous conversion mode.

uint32_t	delay
	Set the phase compensation.

afe_chn_mode_t	chnMode
	Select if channel is in bypassed mode.

afe_pga_state_t	pgaGainSel
	Select the analog gain applied to the input signal.

afe_chn_osr_mode_t	decimOSR
	Select the over sampling ration.

afe_chn_event_t	chnEvent
	Select DMA or interrupt function.

struct afe_user_config_t

This structure keeps the configuration for the AFE module.

Data Fields
bool	lowPowerEnable
	Enable low power mode.

afe_result_format_mode_t	resultFormat
	Select the result format.

afe_clk_divider_mode_t	clkDividerMode
	Select the clock divider ration for the modulator clock.

afe_clk_src_mode_t	clkSrcMode
	Select clock source for modulator clock.

uint8_t	startupCnt
	Select the start up delay of modulators.

struct afe_delay_config_t

This structure keeps the phase delay of each AFE channel.

Data Fields
uint32_t	delayChn0
	Phase compensation of channel0. More...

uint32_t	delayChn1
	Phase compensation of channel1. More...

uint32_t	delayChn2
	Phase compensation of channel2. More...

Field Documentation

uint32_t afe_delay_config_t::delayChn0

uint32_t afe_delay_config_t::delayChn1

uint32_t afe_delay_config_t::delayChn2

Enumeration Type Documentation

enum afe_pga_state_t

Enumerator
kAfePgaDisable	PGA disabled.
kAfePgaGain1	Input gained by 1.
kAfePgaGain2	Input gained by 2.
kAfePgaGain4	Input gained by 4.
kAfePgaGain8	Input gained by 8.
kAfePgaGain16	Input gained by 16.
kAfePgaGain32	Input gained by 32.

enum afe_chn_mode_t

Enumerator
kAfeNormal	Normal channel mode.
kAfeBypassExternCltPosEdge	Bypassed channel mode - external clock selected, positive edge for registering data by the decimation filter.
kAfeBypassExternClkNegEdge	Bypassed channel mode - external clock selected, negative edge for registering data by the decimation filter.
kAfeBypassInternClkPosEdge	Bypassed channel mode - internal clock selected, positive edge for registering data by the decimation filter.
kAfeBypassInternClkNegEdge	Bypassed channel mode - external clock selected, negative edge for registering data by the decimation filter.

enum afe_chn_event_t

Enumerator
kAfeNoneReq	None request is enabled if conversion is completed.
kAfeIntReq	Interrupt request is enabled if conversion is completed.
kAfeDmaReq	DMA request is enabled if conversion is completed.

enum afe_flag_t

Enumerator
kAfeOverflowFlag	Indicates if a previous conversion result has not been read and new data has already arrived.
kAfeReadyFlag	Indicates whether a channel is ready to conversion.
kAfeConvCompleteFlag	Indicates whether a conversion is complete.

Function Documentation

afe_status_t AFE_DRV_StructInitUserConfigDefault ( afe_user_config_t * userConfigPtr )

This function fills the afe_user_config_t structure with default settings. These setting are:

.lowPowerEnable = false
.resultFormat = kAfeResultFormatLeft
.clkDividerMode = kAfeClkDividerInputOf2
.clkSrcMode = kAfeClkSrcClk0
.startupCnt = 125

Parameters

userConfigPtr Pointer to structure of "afe_user_config_t".

Returns: Execution status.

afe_status_t AFE_DRV_StructInitChnConfigDefault ( afe_chn_config_t * chnConfigPtr )

This function fills the afe_chn_config_t structure with default settings. These setting are:

.hwTriggerEnable = false
.continuousConvEnable = false
.chnMode = kAfeNormal
.decimOSR = kAfeDecOsrOf64
.delay = 0
.pgaGainSel = kAfePgaGain1
.chnEvent = kAfeNoneReq

Parameters

chnConfigPtr Pointer to structure of "afe_chn_config_t".

Returns: Execution status.

afe_status_t AFE_DRV_Init	(	uint32_t	instance,
		afe_user_config_t *	userConfigPtr
	)

This function configures the AFE module for the configuration which are shared by all channels.

Parameters

instance	The AFE instance number.
userConfigPtr	Pointer to structure of "afe_user_config_t". If startupCnt parameter is less than two, this value is calculated according to equation Statup_cnt = (clk_freq/clk_div)*20e-6.

Returns: Execution status.

afe_status_t AFE_DRV_ChnInit	(	uint32_t	instance,
		uint32_t	chn,
		afe_chn_config_t *	chnConfigPtr
	)

This function configures the selected AFE channel.

Parameters

instance	The AFE instance number.
chn	Channel which will be triggered.
chnConfigPtr	Pointer to structure of "afe_chn_config_t".

Returns: Execution status.

void AFE_DRV_Enable	(	uint32_t	instance,
		bool	enable
	)

This function enables or disables all channels whose SD_MOD_EN and DEC_EN bits are asserted.

Parameters

instance	The AFE instance number.
enable	Enable (true) or disable (false) all ADCs and filters.

void AFE_DRV_WaitConvDone	(	uint32_t	instance,
		uint32_t	chn
	)

This function holds the program until the last conversion is complete.

Parameters

instance	The AFE instance number.
chn	Channel which is triggered.

void AFE_DRV_WaitChnReady	(	uint32_t	instance,
		uint32_t	chn
	)

This function holds the program until the channel is ready for conversion.

Parameters

instance	The AFE instance number.
chn	Channel which is triggered.

void AFE_DRV_SoftTriggerConv	(	uint32_t	instance,
		uint32_t	chnMask
	)

This function triggers the AFE conversion by executing a software command. It starts the conversion on selected channels if the software trigger option is selected for the channels.

Parameters

instance	The AFE instance number.
chnMask	Channel(s) mask which is triggered.

bool AFE_DRV_GetChnFlag	(	uint32_t	instance,
		uint32_t	chn,
		afe_flag_t	flag
	)

This function returns the selected flag of the desired channel.

Parameters

instance	The AFE instance number.
chn	The AFE Channel.
flag	Indicated event, see to "afe_flag_t".

Returns: Assertion of indicated event.

uint32_t AFE_DRV_GetChnConvValRaw	(	uint32_t	instance,
		uint32_t	chn
	)

This function returns the conversion value of the selected channel. The returned value could be left or right adjusted according to the AFE module configuration.

Parameters

instance	The AFE instance number.
chn	The AFE Channel.

Returns: Conversion value.

int32_t AFE_DRV_GetChnConvVal	(	uint32_t	instance,
		uint32_t	chn
	)

This function returns the conversion value of the selected channel. The returned value is in the twos complement (right adjusted) format.

Parameters

instance	The AFE instance number.
chn	The AFE Channel.

Returns: Conversion value in 2's complement format.

void AFE_DRV_Deinit ( uint32_t instance )

When the AFE is no longer used, calling this function shuts down the device to reduce power consumption.

Parameters

instance The AFE instance number.

void AFE_DRV_ChnDeinit	(	uint32_t	instance,
		uint32_t	chn
	)

De-initializes the selected AFE channel configuration and interrupt.

Parameters

instance	The AFE instance number.
chn	The AFE Channel.

void AFE_DRV_AssertDelayOk ( uint32_t instance )

This function should be called after all desired channel's delay registers are loaded. Values in channel's delay registers are active after calling this function and after the conversation starts.

Parameters

instance The AFE instance number.

void AFE_DRV_SetPhaseDelays	(	uint32_t	instance,
		afe_delay_config_t *	delayConfigPtr
	)

This function sets the phase delays for channels. This delay is inserted before the trigger response of the decimation filters. The delay is used to provide a phase compensation between AFE channels in step of prescaled modulator clock periods. The DelayOk bit is asserted in this function and the 'AFE_DRV_AssertDelayOk()' function doesn't have to be called. The delays for each channel are stored in a 'afe_delay_config_t' structure.

Parameters

instance	The AFE instance number.
delayConfigPtr	Pointer to structure of "afe_delay_config_t".

Variable Documentation

AFE_Type* const g_afeBase[]

const IRQn_Type g_afeIrqId[]

Overview

Channel configuration structures

User configuration structures

Initialization

Measuring

Data Structures

Enumerations

Functions

Variables

Data Structure Documentation

Data Fields

Data Fields

Data Fields

Field Documentation

Enumeration Type Documentation

Function Documentation

Variable Documentation