rs485_driver.h File Reference

RS485 passive sniffer (RX-only) driver. More...

#include "driver/uart.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

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Data Structures
struct	rs485_driver_event_t
	RS485 driver event structure. More...
struct	rs485_driver_config_t
	RS485 driver configuration structure. More...
struct	rs485_driver_t
	RS485 driver type structure. More...

Macros
#define	RS485_DRIVER_TASK_NAME   ("RS485_DRV")
#define	RS485_DRIVER_TASK_STACK_DEPTH   (4096U)
#define	RS485_DRIVER_TASK_PRIORITY   (16U)
#define	RS485_DRIVER_TASK_CPU_AFFINITY   (0U)
#define	RS485_DRIVER_TASK_BUFFER_SIZE   (256U)
#define	RS485_DRIVER_TASK_NOTIFY_STOP_BIT   (1U << 0U)

Enumerations
enum	rs485_driver_event_flags_t { RS485_DRIVER_EVENT_FLAG_DATA = (1U << 0) , RS485_DRIVER_EVENT_FLAG_RX_TIMEOUT = (1U << 1) , RS485_DRIVER_EVENT_FLAG_OVERFLOW = (1U << 2) , RS485_DRIVER_EVENT_FLAG_PARITY = (1U << 3) }
	RS485 driver event flags enum. More...

Functions
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.

Detailed Description

RS485 passive sniffer (RX-only) driver.

Author

Abanoub Salah

• Does not transmit or control DE/RE lines
• Passively listens to bus traffic using UART RX
• Provide a task that provide events as they come to provided callback

Macro Definition Documentation

RS485_DRIVER_TASK_BUFFER_SIZE

#define RS485_DRIVER_TASK_BUFFER_SIZE   (256U)

Event buffer size

RS485_DRIVER_TASK_CPU_AFFINITY

#define RS485_DRIVER_TASK_CPU_AFFINITY   (0U)

CPU affinity

RS485_DRIVER_TASK_NAME

#define RS485_DRIVER_TASK_NAME   ("RS485_DRV")

Task name

RS485_DRIVER_TASK_NOTIFY_STOP_BIT

#define RS485_DRIVER_TASK_NOTIFY_STOP_BIT   (1U << 0U)

Task stop bit

RS485_DRIVER_TASK_PRIORITY

#define RS485_DRIVER_TASK_PRIORITY   (16U)

Priority

RS485_DRIVER_TASK_STACK_DEPTH

#define RS485_DRIVER_TASK_STACK_DEPTH   (4096U)

Stack depth

Enumeration Type Documentation

rs485_driver_event_flags_t

enum rs485_driver_event_flags_t

RS485 driver event flags enum.

Enumerator
RS485_DRIVER_EVENT_FLAG_DATA	Data flag
RS485_DRIVER_EVENT_FLAG_RX_TIMEOUT	Rx timeout flag
RS485_DRIVER_EVENT_FLAG_OVERFLOW	Overflow flag
RS485_DRIVER_EVENT_FLAG_PARITY	Parity flag

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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