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boot.c
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boot.c
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/*********************************************************************
* Software License Agreement (BSD License)
*
* Copyright (c) 2018
*
* Balint Cristian <cristian dot balint at gmail dot com>
*
* TinnyModbus
*
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* * Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*********************************************************************/
/*
boot.c (BootLoader application)
*/
#include <stdio.h>
#include <stdlib.h>
#include <avr/io.h>
#include <avr/wdt.h>
#include <avr/eeprom.h>
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include "crc16.h"
#include "eeprom.h"
#include "pgmflash.h"
#include "softuart.h"
extern uint8_t IDModbus;
// modbus frames
uint8_t modbus[40];
// Software version string
static const char PROGMEM BLVers[4] = "0.01"; // 4 octet ASCII
static void send_modbus_array( uint8_t *sendbuff, const uint8_t len )
{
// calc checksum
uint16_t csum = clcCRC16( sendbuff, len-2 );
// insert checksum
sendbuff[len-2] = csum & 0xFF;
sendbuff[len-1] = csum >> 8;
// send over rs485 wire
softuart_tx_array( &sendbuff[0], len );
}
static void send_modbus_exception( uint8_t *sendbuff, uint8_t errcode )
{
sendbuff[1] += 0x80; // exception flag
sendbuff[2] = errcode; // exception code
send_modbus_array( &sendbuff[0], 5 );
}
int main( void )
{
cli();
wdt_disable();
__asm volatile
(
// jmp into bootload if pin 5 active
" cbi %[ADDRPRTB], %[PINPB5] \n\t"
" cbi %[ADDRDDRB], %[PINPB5] \n\t"
" sbic %[ADDRPINB], %[PINPB5] \n\t"
" rjmp gotoflashld \n\t"
// jmp into bootload if start vector is bad
" ldi r30, 0x00 \n\t"
" ldi r31, 0x00 \n\t"
" lpm r29, Z+ \n\t"
" cpi r29, 0xFF \n\t"
" brne gotoflashld \n\t"
" lpm r29, Z \n\t"
" cpi r29, 0xCD \n\t"
" brne gotoflashld \n\t"
// jmp into bootload if BOOT mark in stack
" pop r30 \n\t"
" cpi r30, 0x54 \n\t" // 'T'
" brne gotomainapp \n\t"
" pop r30 \n\t"
" cpi r30, 0x4F \n\t" // 'O'
" brne gotomainapp \n\t"
" pop r30 \n\t"
" cpi r30, 0x4F \n\t" // 'O'
" brne gotomainapp \n\t"
" pop r30 \n\t"
" cpi r30, 0x42 \n\t" // 'B'
" brne gotomainapp \n\t"
" rjmp gotoflashld \n\t"
// jump to main app
// @end of vector table
"gotomainapp:"
" ldi r30, 0x0F \n\t"
" ldi r31, 0x00 \n\t"
" ijmp \n\t"
// bootload
"gotoflashld:"
// reset stack pointer to RAMEND
" ldi r28, lo8(__stack) \n\t"
" ldi r29, hi8(__stack) \n\t"
" out 0x3e, r29 \n\t"
" out 0x3d, r28 \n\t"
:
: [ADDRPRTB] "I" (_SFR_IO_ADDR(PORTB)),
[ADDRDDRB] "I" (_SFR_IO_ADDR(DDRB)),
[ADDRPINB] "I" (_SFR_IO_ADDR(PINB)),
[PINPB5] "I" (PB5)
);
// fetch own slave address from EEPROM
uint8_t IdSv = eeprom_read_byte(&IDModbus);
/*
* receive buffer for modbus frame (fcode = 3,4,6)
* ____________________________________________
* | 1x | 1x | 2x | 2x | 2x |
* |--------+--------+--------+--------+--------|
* | S addr | F code | D addr | D nums | CRC16 |
* |________|________|________|________|________|
* modbus[32->39]
*/
/*
* receive ring buffer for modbus frame (fcode = 16)
* _____________________________________________________
* | 1x | 1x | 2x | 2x | 32x | 2x |
* |--------+--------+--------+--------+--------+--------|
* | S addr | F code | D addr | D nums | DATA | CRC16 |
* |________|________|________|________|________|________|
* modbus[0->39]
*/
// MAX485 rx/tx dir
DDRB |= (1 << DDB3); // PB3 as output pin
for (;;)
{
// shift chain data to left
for (uint8_t k = 1; k < 40; k++)
modbus[k-1] = modbus[k];
// push into chain the new byte
modbus[39] = softuart_rx(); // Receive a byte.
// is our address ?
// is function code 10 ?
// is amount of regs 16 ?
if ( ( modbus[0] == IdSv ) &&
( modbus[1] == 0x10 ) &&
( modbus[5] == 0x10 ) )
{
// is long crc valid ?
uint16_t crc16 = modbus[38];
crc16 |= (uint16_t)modbus[39] << 8;
if ( crc16 == clcCRC16( modbus, 38 ) )
{
//
// Process MODBUS command
//
// data address
uint16_t daddr = modbus[3];
daddr |= (uint16_t)modbus[2] << 8;
// triage cmd
switch( modbus[1] )
{
// write multiple input register
// (we receive pages of 32 octets)
case 0x10:
// don't touch bootloader
// only chunks of 32 octet
if ( ( daddr <= 0x1BE0 ) &&
( daddr % 0x20 == 0 ) )
{
// CD FF (RJMP 0x0DFF)
// overwrite start vector
// to point to bootloader
if ( daddr == 0x0000 )
{
modbus[6] = 0xFF;
modbus[7] = 0xCD;
}
// write page to flash
writePGMFlash( daddr );
// confirm with echo back
send_modbus_array( &modbus[0], 8 );
}
else
{
// illegal address value
send_modbus_exception( &modbus[0], 0x02 );
}
break; // fcode=0x10
} // end switch fcode
} // end with valid crc
} // end valid modbus cmd
// is our address ?
// is function code valid ?
// only 3,6 function code ?
// only one register ?
if ( ( modbus[32+0] == IdSv ) &&
( ( modbus[32+1] == 0x03 ) ||
( modbus[32+1] == 0x06 ) )
)
{
// is short crc valid ?
uint16_t crc16 = modbus[32+6];
crc16 |= (uint16_t)modbus[32+7] << 8;
if ( crc16 == clcCRC16( &modbus[32], 6 ) )
{
//
// Process MODBUS command
//
// data address
uint16_t daddr = modbus[32+3];
daddr |= (uint16_t)modbus[32+2] << 8;
// data amount
uint16_t dnums = modbus[32+5];
dnums |= (uint16_t)modbus[32+4] << 8;
// triage cmd
switch( modbus[32+1] )
{
// read holding register
case 0x03:
// return MODE
if ( daddr == 0x0000 )
{
// requested amount
if ( modbus[32+5] != 0x01 )
{
// illegal data value
send_modbus_exception( &modbus[32+0], 0x03 );
break;
}
modbus[32+2] = 0x02; // mslen
modbus[32+3] = 0x00;
modbus[32+4] = 0x01; // bootload mode
send_modbus_array( &modbus[32+0], 7 );
}
// return SW VERS
if ( daddr == 0x0001 )
{
// requested amount
if ( modbus[32+5] != 0x02 )
{
// illegal data value
send_modbus_exception( &modbus[32+0], 0x03 );
break;
}
modbus[32+2] = 0x04; // mslen
// fetch software version
modbus[32+3] = pgm_read_byte(&BLVers[0]);
modbus[32+4] = pgm_read_byte(&BLVers[1]);
modbus[32+5] = pgm_read_byte(&BLVers[2]);
modbus[32+6] = pgm_read_byte(&BLVers[3]);
send_modbus_array( &modbus[32+0], 9 );
}
break; // fcode = 0x03
case 0x06:
// change MODE
if ( daddr == 0x0000 )
{
// expect set value 0x0000
if ( ( modbus[32+4] == 0x00 ) &&
( modbus[32+5] == 0x00 ) )
{
// confirm mode switch
softuart_tx_array( &modbus[32+0], 8 );
// watchdog @ 4 sec
wdt_enable( WDTO_4S );
// jump to main app
// @end of vector table
__asm volatile
(
" ldi r30, 0x0F \n\t"
" ldi r31, 0x00 \n\t"
" ijmp \n\t"
);
}
else
{
// illegal data value
send_modbus_exception( &modbus[32+0], 0x03 );
}
}
break; // fcode = 0x06
} // end switch fcode
} // end with valid crc
} // end valid modbus cmd
} // end main loop
return 0;
}