Timer Interface
Timer Platform interface
Timer Overview
A timer is a critical component in microcontrollers and embedded systems, used for timekeeping, event scheduling, and generating precise delays or waveforms. Timers operate by counting clock cycles from the microcontroller’s clock source, allowing developers to execute tasks or generate signals at specified intervals.
Timer Operation Modes
The supportted operation modes, trigger sources as supported by the underlying timer.
Mode |
Description |
|---|---|
RS_TIMER_OPERATION_MODE_INPUT_CAPTURE |
Timer is configured for Input Capture operation |
RS_TIMER_OPERATION_MODE_OUTPUT_COMPARE |
Timer is configured for Output compare operation |
RS_TIMER_OPERATION_MODE_EDGE_PWM |
Timer is used to generate edge aligned PWM |
RS_TIMER_OPERATION_MODE_CENTER_PWM |
Timer is used to generate center aligned PWM |
RS_TIMER_OPERATION_MODE_ONE_PULSE |
Timer is used to generate single pulse |
Mode |
Description |
|---|---|
RS_TIMER_TRIGGER_MODE_CONTINUOUS |
Increment continuously |
RS_TIMER_TRIGGER_MODE_EXTERNAL |
Increment via external event |
Mode |
Description |
|---|---|
RS_TIMER_EVENT_TYPE_COUNTER_OVERFLOW |
On counter overflow |
RS_TIMER_EVENT_TYPE_COUNTER_UNDERFLOW |
On counter underflow |
RS_TIMER_EVENT_TYPE_INPUT_CAPTURE |
Input event happened |
Application Interface
The below table captures the functions that are to be called from the application layer.
Function |
Description |
|---|---|
rs_timer_init |
To open timer unit |
rs_timer_configure_channel |
To configures the timer channel |
rs_timer_start_channel |
To starts the timer for the given channel |
rs_timer_stop_channel |
To stops the timer for the given channel |
rs_timer_register_event_callback |
To registers the given callback function for event |
rs_timer_deinit |
To close the timer unit |
Error Code
Every API’s for the timer returns some success or failure values. Please refer below section,
Implementation Guide
Initialize the timer unit
Configure the timer channel under the unit
Register the callback function
Start the timer channel
Callback gets called.
Stop the timer once work is done
Un-Initialize the timer unit
Documentation from the relevant header as follows:
Defines
-
RS_TIMER_TRIGGER_MODE_CONTINUOUS
Increment continously
-
RS_TIMER_TRIGGER_MODE_EXTERNAL
Increment via external event
-
RS_TIMER_OPERATION_MODE_INPUT_CAPTURE
Capture input events
-
RS_TIMER_OPERATION_MODE_OUTPUT_COMPARE
Use for output compare
-
RS_TIMER_OPERATION_MODE_EDGE_PWM
Generate Edge aligned PWM
-
RS_TIMER_OPERATION_MODE_CENTER_PWM
Generate Center aligned PWM
-
RS_TIMER_OPERATION_MODE_ONE_PULSE
One pulse mode
-
RS_TIMER_EVENT_TYPE_COUNTER_OVERFLOW
On Counter Overflow
-
RS_TIMER_EVENT_TYPE_COUNTER_UNDERFLOW
On Counter Underflow
-
RS_TIMER_EVENT_TYPE_INPUT_CAPTURE
When an input event happened
-
RS_TIMER_WIDTH_8_BIT
8 bit resolution
-
RS_TIMER_WIDTH_16_BIT
16 bit resolution
-
RS_TIMER_WIDTH_24_BIT
24 bit resolution
-
RS_TIMER_WIDTH_32_BIT
32 bit resolution
-
RS_TIMER_WIDTH_64_BIT
64 bit resolution
Typedefs
-
typedef struct __rs_timer_channel_config rs_timer_channel_config_t
Structure for setting up each Timer Channel configuration
-
typedef struct __rs_timer_config rs_timer_config_t
Structure for setting up each Timer Unit configuration
-
typedef void (*rs_timer_callback_event)(rs_handle_t handle, rs_ret_val_t event, uint32_t u32_channel, void *ptr_arg)
Callback function format.
This callback function is called on an event
- Param handle:
[in] - Handle to the Timer unit
- Param event:
[in] - Event that initiated the callback or error code
- Param u32_channel:
[in] - Channel for which the event is for
- Param ptr_arg:
[in] - Argument as provided during register callback
- Return:
None
Functions
-
rs_handle_t rs_timer_init(rs_timer_config_t *ptr_timer_config)
-
rs_ret_val_t rs_timer_configure_channel(rs_handle_t handle, rs_timer_channel_config_t *ptr_config)
Configures the Timer channel.
This function configures/reconfigures the channel as per the given configuration
- Parameters:
handle – [in] - Handle to the Timer unit
ptr_config – [in] - Pointer to the configuration structure
- Returns:
0 on success or error code on failure
-
rs_ret_val_t rs_timer_start_channel(rs_handle_t handle, uint32_t u32_channel)
Starts the timer for the given channel.
This function intitiates the timer operation for the given Timer channel
- Parameters:
handle – [in] - Handle to the Timer unit
u32_channel – [in] - Channel number
- Returns:
0 on success or error code on failure
-
rs_ret_val_t rs_timer_stop_channel(rs_handle_t handle, uint32_t u32_channel)
Stops the timer for the given channel.
This function stops the timer operation for the given channel
- Parameters:
handle – [in] - Handle to the Timer unit
u32_channel – [in] - Channel number
- Returns:
0 on success or error code on failure
-
rs_ret_val_t rs_timer_register_event_callback(rs_handle_t handle, rs_timer_callback_event ptr_func, void *ptr_arg)
-
rs_ret_val_t rs_timer_deinit(rs_handle_t handle)
Uninitializes the Timer Unit.
This function un-initializes the Timer Unit and releases the handle
- Parameters:
handle – [in] - Handle to the Timer Unit
- Returns:
0 on success or error code on failure
-
struct __rs_timer_channel_config
- #include <rs_timer.h>
Structure for setting up each Timer Channel configuration
Public Members
-
uint8_t unit_index
Index to Timer unit as defined by underlying HAL layer
-
uint8_t channel
Channel number inside the unit, Starting from 0 index
-
uint8_t group
Grouping of channel, if supported
-
uint8_t trigger
Trigger source
-
uint8_t oper_mode
Operation mode - One-shot, continuous etc
-
uint8_t ext_event_id
Source of external event as defined by HAL
-
uint8_t event_type
Event up on which call back to be called
-
uint8_t u8_counter
8 bit Counter value
-
uint16_t u16_counter
16 bit Counter value
-
uint32_t u32_counter
32 bit Counter value
-
uint64_t u64_counter
32 bit Counter value
-
union __rs_timer_channel_config count_val
-
uint8_t unit_index
-
struct __rs_timer_config
- #include <rs_timer.h>
Structure for setting up each Timer Unit configuration