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openblt/Target/Source/_template/mbrtu.c

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/************************************************************************************//**
* \file Source/_template/mbrtu.c
* \brief Bootloader Modbus RTU communication interface source file.
* \ingroup Target__template_mbrtu
* \internal
*----------------------------------------------------------------------------------------
* C O P Y R I G H T
*----------------------------------------------------------------------------------------
* Copyright (c) 2023 by Feaser http://www.feaser.com All rights reserved
*
*----------------------------------------------------------------------------------------
* L I C E N S E
*----------------------------------------------------------------------------------------
* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You have received a copy of the GNU General Public License along with OpenBLT. It
* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
*
* \endinternal
****************************************************************************************/
/************************************************************************************//**
* \defgroup Target__template_mbrtu Modbus RTU driver of a port
* \brief This module implements the Modbus RTU driver of a microcontroller port.
* \details For the most parts, this driver is already implemented. The only parts that
* need porting are the UART initialization, byte reception and byte
* transmission.
* \ingroup Target__template
****************************************************************************************/
/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h" /* bootloader generic header */
#if (BOOT_COM_MBRTU_ENABLE > 0)
/* TODO ##Port Include microcontroller peripheral driver header files here. */
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Timeout for transmitting a byte in milliseconds. */
#define MBRTU_BYTE_TX_TIMEOUT_MS (10u)
/****************************************************************************************
* Local data declarations
****************************************************************************************/
/** \brief Stores the number of free running counter ticks that represents the 3.5
* character delay time (T3_5) for Modbus RTU.
*/
static blt_int16u mbRtuT3_5Ticks;
/****************************************************************************************
* Function prototypes
****************************************************************************************/
static blt_bool MbRtuReceiveByte(blt_int8u *data);
static void MbRtuTransmitByte(blt_int8u data, blt_bool end_of_packet);
/************************************************************************************//**
** \brief Initializes the Modbus RTU communication interface.
** \attention It is the application's responsibility to initialize a timer peripheral
** to have an upwards counting free running counter, which runs at 100 kHz.
** \return none.
**
****************************************************************************************/
void MbRtuInit(void)
{
blt_int16u startTimeTicks;
blt_int16u deltaTimeTicks;
blt_int16u currentTimeTicks;
blt_int8u rxDummy;
/* TODO ##Port Perform compile time assertion to check that the configured UART channel
* is actually supported by this driver. The example is for a driver where UART
* channels 0 - 2 are supported.
*/
ASSERT_CT((BOOT_COM_MBRTU_CHANNEL_INDEX == 0) ||
(BOOT_COM_MBRTU_CHANNEL_INDEX == 1) ||
(BOOT_COM_MBRTU_CHANNEL_INDEX == 2));
/* calculate the 3.5 character delay time in free running counter ticks. note that
* the free running counter runs at 100 kHz, so one tick is 10 us. For baudrates >
* 19200 bps, it can be fixed to 1750 us.
*/
if (BOOT_COM_MBRTU_BAUDRATE > 19200)
{
/* set T3_5 time to a fixed value of 1750 us. */
mbRtuT3_5Ticks = 175;
}
/* calculate the T3_5 time, because the baudrate is <= 19200 bps. */
else
{
/* T3_5 [us * 10] = 3.5 * Tchar = 3.5 * 11 * 100000 / baudrate = 3850000 / baudrate.
* make sure to do integer round up though. Make sure to add 1 to adjust for 10us
* timer resolution inaccuracy.
*/
mbRtuT3_5Ticks = (blt_int16u)(((3850000UL + (BOOT_COM_MBRTU_BAUDRATE - 1U)) /
BOOT_COM_MBRTU_BAUDRATE) + 1);
}
/* TODO ##Port Configure and initialize the UART peripheral for the configured UART
* channel:
* - The communication speed should be set to the value configured with
* BOOT_COM_MBRTU_BAUDRATE.
* - Set the number of stopbits as configurec with BOOT_COM_MBRTU_STOPBITS.
* - Set the parity as configured with BOOT_COM_MBRTU_PARITY (0 for no parity, 1 for
* odd parity and 2 for event parity).
* Keep in mind that the bootloader runs in polling mode so without interrupts. For
* this reason make sure not to configure the UART peripheral for interrupt driven
* operation.
*/
/* enable the receiver output to be able to receive. */
MbRtuDriverOutputControlHook(BLT_FALSE);
/* wait for idle line detection. This is T3_5 time after reception of the last byte. */
startTimeTicks = MbRtuFreeRunningCounterGet();
do
{
/* service the watchdog. */
CopService();
/* get the current value of the free running counter. */
currentTimeTicks = MbRtuFreeRunningCounterGet();
/* check if a byte was received while waiting for the idle line. */
if (MbRtuReceiveByte(&rxDummy) == BLT_TRUE)
{
/* restart the idle line detection. */
startTimeTicks = currentTimeTicks;
}
/* calculate the number of ticks that elapsed since the start or since the last
* byte reception. Note that this calculation works, even if the free running counter
* overflowed.
*/
deltaTimeTicks = currentTimeTicks - startTimeTicks;
}
while (deltaTimeTicks < mbRtuT3_5Ticks);
} /*** end of MbRtuInit ***/
/************************************************************************************//**
** \brief Transmits a packet formatted for the communication interface.
** \param data Pointer to byte array with data that it to be transmitted.
** \param len Number of bytes that are to be transmitted.
** \return none.
**
****************************************************************************************/
void MbRtuTransmitPacket(blt_int8u *data, blt_int8u len)
{
blt_int16u data_index;
blt_int16u checksum;
blt_bool endOfPacket = BLT_FALSE;
/* Made static to lower stack load and +5 for Modbus RTU packet overhead. */
static blt_int8u txPacket[BOOT_COM_MBRTU_TX_MAX_DATA + 5];
/* On Modbus RTU, there must always be a T3_5 time separation between packet trans-
* missions.
*
* This bootloader uses XCP packets embedded in Modbus RTU packets. The XCP
* communication is always request / response based. That means that this packet is
* a response packet and it will only be sent, after the reception of a request packet.
*
* A response packet is only deemed valid, after the T3_5 idle time. This module
* implements the T3_5 end-of-packet time event detection. Consequently, it is already
* guaranteed that there is T3_5 between subsequent packet transmissions. As such, no
* further T3_5 wait time is needed here.
*/
/* verify validity of the len-parameter */
ASSERT_RT(len <= BOOT_COM_MBRTU_TX_MAX_DATA);
/* construct the Modbus RTU packet. start by adding the slave address. */
txPacket[0] = BOOT_COM_MBRTU_NODE_ID;
/* add the user-defined function code for embedding XCP packets. */
txPacket[1] = BOOT_COM_MBRTU_FCT_CODE_USER_XCP;
/* add the XCP packet length. */
txPacket[2] = len;
/* copy the XCP packet data. */
CpuMemCopy((blt_int32u)&txPacket[3], (blt_int32u)data, len);
/* calculate the checksum for the packet, including slave address, function code and
* extra XCP length.
*/
checksum = MbRtuCrcCalculate(&txPacket[0], len + 3);
/* add the checksum at the end of the packet */
txPacket[len + 3] = (blt_int8u)(checksum & 0xff);
txPacket[len + 4] = (blt_int8u)(checksum >> 8);
/* enable the driver output to be able to send. just make sure to wait a little around
* the togglng of the DE/NRE pin.
*/
MbRtuDelay(BOOT_COM_MBRTU_DRIVER_OUTPUT_ENABLE_DELAY_US);
MbRtuDriverOutputControlHook(BLT_TRUE);
MbRtuDelay(BOOT_COM_MBRTU_DRIVER_OUTPUT_ENABLE_DELAY_US);
/* transmit all the packet bytes one-by-one */
for (data_index = 0; data_index < (len + 5); data_index++)
{
/* keep the watchdog happy */
CopService();
/* last byte of the packet? */
if (data_index == ((len + 5) - 1))
{
/* update the end of packet flag. */
endOfPacket = BLT_TRUE;
}
/* write byte */
MbRtuTransmitByte(txPacket[data_index], endOfPacket);
}
/* enable the receiver output to be able to receive again. just make sure to wait a
* little around the togglng of the DE/NRE pin.
*/
MbRtuDelay(BOOT_COM_MBRTU_DRIVER_OUTPUT_DISABLE_DELAY_US);
MbRtuDriverOutputControlHook(BLT_FALSE);
MbRtuDelay(BOOT_COM_MBRTU_DRIVER_OUTPUT_DISABLE_DELAY_US);
} /*** end of MbRtuTransmitPacket ***/
/************************************************************************************//**
** \brief Receives a communication interface packet if one is present.
** \param data Pointer to byte array where the data is to be stored.
** \param len Pointer where the length of the packet is to be stored.
** \return BLT_TRUE if a packet was received, BLT_FALSE otherwise.
**
****************************************************************************************/
blt_bool MbRtuReceivePacket(blt_int8u *data, blt_int8u *len)
{
blt_bool result = BLT_FALSE;
blt_int8u rxByte;
blt_int16u currentTimeTicks;
blt_int16u deltaTimeTicks;
blt_int16u checksumCalculated;
blt_int16u checksumReceived;
/* Made static to lower stack load and +5 for Modbus RTU packet overhead. */
static blt_int8u rxPacket[BOOT_COM_MBRTU_RX_MAX_DATA + 5];
static blt_int8u rxLength = 0;
static blt_bool packetRxInProgress = BLT_FALSE;
static blt_int16u lastRxByteTimeTicks = 0;
/* get the current value of the free running counter. */
currentTimeTicks = MbRtuFreeRunningCounterGet();
/* check for a newly received byte. */
if (MbRtuReceiveByte(&rxByte) == BLT_TRUE)
{
/* store the time at which the byte was received. */
lastRxByteTimeTicks = currentTimeTicks;
/* is this the potential start of a new packet? */
if (packetRxInProgress == BLT_FALSE)
{
/* initialize the reception of a new packet. */
rxLength = 0;
packetRxInProgress = BLT_TRUE;
}
/* store the newly received byte in the buffer, with buffer overrun protection. */
if (rxLength < (sizeof(rxPacket)/sizeof(rxPacket[0])))
{
rxPacket[rxLength] = rxByte;
rxLength++;
}
/* buffer overrun occurred. received packet was longer than supported so discard
* the packet to try and sync to the next one.
*/
else
{
/* discard the partially received packet. */
packetRxInProgress = BLT_FALSE;
}
}
/* only attempt to detect the end of packet, when a reception is in progress. */
if (packetRxInProgress == BLT_TRUE)
{
/* calculate the number of ticks that elapsed since the last byte reception. note
* that this calculation works, even if the free running counter overflowed.
*/
deltaTimeTicks = currentTimeTicks - lastRxByteTimeTicks;
/* packet reception is assumed complete after T3_5 of not receiving new data. */
if (deltaTimeTicks >= mbRtuT3_5Ticks)
{
/* a Modbus RTU packet consists of at least the address field, function code and
* 16-bit CRC. Validate the packet length based on this info.
*/
if (rxLength >= 4)
{
/* calculate the packet checksum. */
checksumCalculated = MbRtuCrcCalculate(&rxPacket[0], rxLength - 2);
/* extract the checksum received with the packet. */
checksumReceived = rxPacket[rxLength - 2] | (rxPacket[rxLength - 1] << 8);
/* only continue with packet processing if the checksums match. */
if (checksumCalculated == checksumReceived)
{
/* we are only interested in Modbus RTU packets that are addressed to us and
* have an XCP packet embedded.
*/
if ( (rxPacket[0] == BOOT_COM_MBRTU_NODE_ID) &&
(rxPacket[1] == BOOT_COM_MBRTU_FCT_CODE_USER_XCP) )
{
/* An XCP packet embedded in a Modbus RTU packet has an extra XCP packet
* length value. Use it to double-check that the packet length is valid.
*/
if (rxPacket[2] == (rxLength - 5))
{
/* copy the packet's XCP data. */
CpuMemCopy((blt_int32u)data, (blt_int32u)&rxPacket[3], rxLength - 5);
/* set the packet's XCP length. */
*len = rxLength - 5;
/* update the result to success to indicate that this XCP packet is ready
* for processing.
*/
result = BLT_TRUE;
}
}
}
}
/* reset the packet reception in progress flag, to be able to receive the next. */
packetRxInProgress = BLT_FALSE;
}
}
/* give the result back to the caller. */
return result;
} /*** end of MbRtuReceivePacket ***/
/************************************************************************************//**
** \brief Receives a communication interface byte if one is present.
** \param data Pointer to byte where the data is to be stored.
** \return BLT_TRUE if a byte was received, BLT_FALSE otherwise.
**
****************************************************************************************/
static blt_bool MbRtuReceiveByte(blt_int8u *data)
{
blt_bool result = BLT_FALSE;
/* TODO ##Port Check if a new byte was received on the configured channel. This is
* typically done by checking the reception register not empty flag.
*/
if (1 == 0)
{
/* update the result */
result = BLT_TRUE;
/* TODO ##Port check for a frame error. This is typically done by checking the frame
* error bit in a UART status or error register. The frame error check is important
* because it can detect a missing stopbit. On an RS485 bus without bias resistors,
* the A-B differential voltage is 0. For an RS485 transceiver this is neither a 0
* nor a 1 bit, so undefined. Most RS485 transceivers feature a reception failsafe
* function to drive the Rx output (going to the UART Rx) to a defined state of logic
* 1. In case the used RS485 transceiver doesn't have such a feature, it typically
* leaves the Rx output in a logic 0 state. This means that after the stop bit of the
* last packet byte, the UART Rx input sees a logic 0, and assumes it is a start bit.
* The remaining data bits will always be 0 and, most importantly no stop bit is
* present, causing a framing error. Long story short: if you don't check for the
* framing error flag, you might receive an extra byte with value 0, which is not
* actually transmitted on the RS485 bus. You can catch and ignore this byte by doing
* a frame error check.
*/
if (1 == 0)
{
/* TODO ##Port Reset the frame error bit in the UART peripheral. Note that this
* often happens automatically by reading out the UART data register, which is done
* later in this function. So chances are you won't have to do anything extra here.
*/
/* ignore the byte because of a detected frame error. */
result = BLT_FALSE;
}
#if (BOOT_COM_MBRTU_PARITY > 0)
/* TODO ##Port Check if a parity error. This is typically done by checking the parity
* error bit in the UART status or error register.
*/
if (1 == 0)
{
/* TODO ##Port Reset the parity error bit in the UART peripheral. Note that this
* often happens automatically by reading out the UART data register, which is done
* later in this function. So chances are you won't have to do anything extra here.
*/
/* ignore the byte because of a detected parity error. */
result = BLT_FALSE;
}
#endif
/* TODO ##Port Retrieve and store the newly received byte in *data. */
*data = 0;
}
/* give the result back to the caller */
return result;
} /*** end of MbRtuReceiveByte ***/
/************************************************************************************//**
** \brief Transmits a communication interface byte.
** \param data Value of byte that is to be transmitted.
** \param end_of_packet BLT_TRUE if this is the last byte of the packet, BLT_FALSE
** otherwise.
** \return none.
**
****************************************************************************************/
static void MbRtuTransmitByte(blt_int8u data, blt_bool end_of_packet)
{
blt_int32u timeout;
/* TODO ##Port Write the byte value in 'data' to the transmit register of the UART
* peripheral such that the transmission of the byte value is started.
*/
/* set timeout time to wait for transmit completion. */
timeout = TimerGet() + MBRTU_BYTE_TX_TIMEOUT_MS;
/* not the last byte of the packet? */
if (end_of_packet == BLT_FALSE)
{
/* TODO ##Port Wait in a loop, with timeout, until the UART peripheral reports that
* the data was shifted out of its transmit register. This is typically done by
* reading out a transmit register empty flag.
*/
/* wait for tx holding register to be empty */
while (1 == 0)
{
/* keep the watchdog happy. */
CopService();
/* break loop upon timeout. this would indicate a hardware failure. */
if (TimerGet() > timeout)
{
break;
}
}
}
/* this is the last byte of a packet. */
else
{
/* TODO ##Port Wait in a loop, with timeout, until the UART peripheral reports that
* the data transmit was successfully completed. This is typically done by reading
* out a transmit complete flag.
*/
/* wait for tx complete flag to be set. this is needed for the last byte, otherwise
* the transceiver's transmit output gets disabled with
* MbRtuDriverOutputControlHook() before the byte reception completes.
*/
while (1 == 0)
{
/* keep the watchdog happy. */
CopService();
/* break loop upon timeout. this would indicate a hardware failure. */
if (TimerGet() > timeout)
{
break;
}
}
}
} /*** end of MbRtuTransmitByte ***/
/************************************************************************************//**
** \brief Obtains the counter value of the 100 kHz free running counter. Note that
** each count represent 10 us. The Modbus RTU communication module uses this
** free running counter for Modbus RTU packet timing related purposes. The
** already available 1 ms timer does not have the needed resolution for this
** purpose.
** \return Current value of the free running counter.
**
****************************************************************************************/
blt_int16u MbRtuFreeRunningCounterGet(void)
{
blt_int16u result;
/* TODO ##Port Store the current value of the 100 kHz free running counter in the
* result variable.
*/
result = 0;
/* give the result back to the caller. */
return result;
} /*** end of MbRtuFreeRunningCounterGet ***/
#endif /* BOOT_COM_MBRTU_ENABLE > 0 */
/*********************************** end of mbrtu.c ************************************/
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