timer.c File Reference

Implementation for for iSensor-SPI-Buffer timer module. Covers microsecond timer and PPS timer. More...

#include "reg.h"
#include "timer.h"
#include "dio.h"
#include "main.h"

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Functions
static void	InitTIM2 (uint32_t timerfreq)
	Enables IMU sample timestamp timer. More...
static void	InitTIM8 ()
	Enables TIM8 as general 1MHz timer.
static void	ConfigurePPSPins (uint32_t enable)
	Configure PPS timer based on DIO_INPUT_CONFIG value. More...
static void	DWT_Init ()
	Init DWT peripheral. More...
void	Timer_Init ()
	Initialize all timers for operation. More...
void	Timer_Check_PPS_Unlock ()
	Check if the PPS signal is unlocked (greater than 1100ms since last PPS strobe) More...
void	Timer_Sleep_Microseconds (uint32_t microseconds)
	Blocking sleep function call. More...
uint32_t	Timer_Get_Microsecond_Timestamp ()
	Gets the current 32-bit value from the IMU sample timestamp timer. More...
uint32_t	Timer_Get_PPS_Timestamp ()
	Gets the current 32-bit value from PPS timestamp registers. More...
void	Timer_Clear_Microsecond_Timer ()
	Reset TIM2 counter to 0. More...
void	Timer_Enable_PPS ()
	Enable PPS input for time stamp synchronization (improved long term stability over 20ppm crystal). More...
void	Timer_Disable_PPS ()
	Disable PPS timer functionality. More...
void	Timer_Increment_PPS_Time ()
	Increment PPS timestamp by 1. More...

Variables
uint32_t	g_PPSInterruptMask = 0
static TIM_HandleTypeDef	htim2
static TIM_HandleTypeDef	htim8
static uint32_t	PPS_TickCount
static uint32_t	PPS_MaxTickCount

Detailed Description

Implementation for for iSensor-SPI-Buffer timer module. Covers microsecond timer and PPS timer.

Copyright (c) Analog Devices Inc, 2020 All Rights Reserved.

Date

6/26/2020

Author

A. Nolan (alex..nosp@m.nola.nosp@m.n@ana.nosp@m.log..nosp@m.com)

Function Documentation

ConfigurePPSPins()

static void ConfigurePPSPins ( uint32_t  enable )

static

Configure PPS timer based on DIO_INPUT_CONFIG value.

Parameters

enable

Bool flagging if PPS functionality is being enabled or disabled

This function sets up the PPS input pin, as well as the expected "PPS" period.

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DWT_Init()

static void DWT_Init ( )

static

Init DWT peripheral.

Returns

void

This peripheral is used to count microseconds for the timer module.

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InitTIM2()

static void InitTIM2 ( uint32_t  timerfreq )

static

Enables IMU sample timestamp timer.

Parameters

timerfreq

The desired timer freq (in Hz)

Returns

void

This function should be called as part of the buffered data acquisition startup process. The enabled timer is TIM2 (32 bit)

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Timer_Check_PPS_Unlock()

void Timer_Check_PPS_Unlock

(

)

Check if the PPS signal is unlocked (greater than 1100ms since last PPS strobe)

Returns

void

This function should be periodically called as part of the firmware housekeeping process

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Timer_Clear_Microsecond_Timer()

void Timer_Clear_Microsecond_Timer

(

)

Reset TIM2 counter to 0.

Returns

void

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Timer_Disable_PPS()

void Timer_Disable_PPS

(

)

Disable PPS timer functionality.

Returns

void

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Timer_Enable_PPS()

void Timer_Enable_PPS

(

)

Enable PPS input for time stamp synchronization (improved long term stability over 20ppm crystal).

Returns

void

The PPS input can be on any of the DIOx_Slave pins (host processor the iSensor-SPI-Buffer). The selected pin is configured by the PPS_SELECT field in the DIO_INPUT_CONFIG register. The trigger polarity for the PPS signal is configured by the PPS_POLARITY field in the DIO_INPUT_CONFIG register.

Pins:

DIO1: PB4 -> EXTI4 interrupt DIO2: PB8 -> EXTI9_5 interrupt, mask (1 << 8) DIO3: PC7 -> EXTI9_5 interrupt, mask (1 << 7) DIO4: PA8 -> EXTI9_5 interrupt, mask (1 << 8)

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Timer_Get_Microsecond_Timestamp()

uint32_t Timer_Get_Microsecond_Timestamp

(

)

Gets the current 32-bit value from the IMU sample timestamp timer.

Returns

The timer value

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Timer_Get_PPS_Timestamp()

uint32_t Timer_Get_PPS_Timestamp

(

)

Gets the current 32-bit value from PPS timestamp registers.

Returns

The PPS counter value

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Timer_Increment_PPS_Time()

void Timer_Increment_PPS_Time

(

)

Increment PPS timestamp by 1.

Returns

void

This function should be called whenever a PPS interrupt is generated. It handles PPS tick count incrementation, and resetting the microsecond timestamp every time one second has elapsed.

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Timer_Init()

void Timer_Init

(

)

Initialize all timers for operation.

Returns

void

Timer 2 is used as a 1MHz timer for the timestamp measurements Timer 8 is used as a timeout timer, also at 1MHz

The DWT timer is used for a polling based timer

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Timer_Sleep_Microseconds()

void Timer_Sleep_Microseconds

(

uint32_t

microseconds

)

Blocking sleep function call.

Parameters

microseconds

The number of microseconds to sleep

Returns

void

This function uses TIM6 to perform delay.

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Variable Documentation

g_PPSInterruptMask

uint32_t g_PPSInterruptMask = 0

PPS interrupt source. Global scope

htim2

TIM_HandleTypeDef htim2

static

TIM2 handle

htim8

TIM_HandleTypeDef htim8

static

TIM8 handle for init

PPS_MaxTickCount

uint32_t PPS_MaxTickCount

static

Number of PPS ticks per sec

PPS_TickCount

uint32_t PPS_TickCount

static

Track number of "PPS" ticks which have occurred in last second