/************************************************************************************//** * \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 ************************************/