rs485_driver.c File Reference

Implementation of the rs485 driver. More...

#include "rs485_driver.h"
#include "esp_log.h"
#include "esp_timer.h"
#include "hal/uart_ll.h"
#include "runtime_tasks.h"

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Macros
#define	RS485_DRIVER_WAIT_ON_RX_QUEUE_MS   (10U)

Functions
static void	rs485_driver_task (void *parameters_void_ptr)
	RS485 Driver task.
static void	rs485_driver_stop_task (void)
	Stop event bus task.
esp_err_t	rs485_driver_init (rs485_driver_t *rs485_drv_ptr, const rs485_driver_config_t *config_ptr)
	Initialize RS485 driver.
uint8_t	rs485_driver_get_bits_count (rs485_driver_t *rs485_drv_ptr)
	Get frame bits count.
void	rs485_driver_deinit (rs485_driver_t *rs485_drv_ptr)
	De-initialize RS485 driver.

Variables
static const char *	TAG = "RS485_DRIVER"
static TaskHandle_t	rs485_driver_task_handle = NULL
runtime_task_config_t	rs485_driver_task_config

Detailed Description

Implementation of the rs485 driver.

• Configured as a passive listener, receive only mode
• Driver event task wait on UART events passing them to callback function

Macro Definition Documentation

RS485_DRIVER_WAIT_ON_RX_QUEUE_MS

#define RS485_DRIVER_WAIT_ON_RX_QUEUE_MS   (10U)

Wait on receiver queue timeout in milli-seconds

Function Documentation

rs485_driver_deinit()

void rs485_driver_deinit

(

rs485_driver_t *

rs485_drv_ptr

)

De-initialize RS485 driver.

Parameters

rs485_drv_ptr

Pointer to RS485 driver structure

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rs485_driver_get_bits_count()

uint8_t rs485_driver_get_bits_count

(

rs485_driver_t *

rs485_drv_ptr

)

Get frame bits count.

Parameters

rs485_drv_ptr

Pointer to RS485 driver structure

Returns

uint8_t Frame bits count

Note

Only call this function after driver initialization otherwise return is unpredictable

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rs485_driver_init()

esp_err_t rs485_driver_init	(	rs485_driver_t *	rs485_drv_ptr,
		const rs485_driver_config_t *	config_ptr
	)

Initialize RS485 driver.

Parameters

rs485_drv_ptr	Pointer to RS485 driver structure
config_ptr	Pointer to RS485 driver configuration structure

Returns

esp_err_t Initialize result

Return values

ESP_OK	Initialize success
ESP_FAIL	Initialize fail
ESP_ERR_INVALID_ARG	Provided invalid argument(s)
ESP_ERR_NO_MEM	No available memory for resource allocation

Note

• Driver doesn't use Tx pin as it act as a sniffer only
  • Pin is set as UART_PIN_NO_CHANGE
  • Mode is set to UART_MODE_RS485_APP_CTRL

UART RX FIFO FULL threshold is set to 128. For typical Modbus 8 to 256 Bytes is typical 128 characters is a practical value in-between and less than driver's event data buffer

UART RX timeout threshold is set to 4 closest integer to 3.5 characters Inter-frame timeout of practical Modbus transaction

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rs485_driver_task()

static void rs485_driver_task ( void *  parameters_void_ptr )

static

RS485 Driver task.

Parameters

parameters_void_ptr

Void pointer to parameters

Note

Call callback function if available on data/error ready

Old data in queue is dropped in case of overflow

Driver provides raw byte stream only with 4 characters timeout, so, frame boundaries must be reconstructed at higher layers

Variable Documentation

rs485_driver_task_config

runtime_task_config_t rs485_driver_task_config

Initial value:

= {.name        = RS485_DRIVER_TASK_NAME,
                                                  .entry       = rs485_driver_task,
                                                  .arg         = NULL,
                                                  .stack_depth = RS485_DRIVER_TASK_STACK_DEPTH,
                                                  .priority    = RS485_DRIVER_TASK_PRIORITY,
                                                  .core_id     = RS485_DRIVER_TASK_CPU_AFFINITY,
                                                  .handle      = &rs485_driver_task_handle,
                                                  .stop_func   = rs485_driver_stop_task}

RS485 Driver task configuration structure

rs485_driver_task_handle

TaskHandle_t rs485_driver_task_handle = NULL

static

RS485 Driver task handle

TAG

const char* TAG = "RS485_DRIVER"

static

RS485 Driver TAG name