razzor/twiboot
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b60a0fe735
twiboot/main.c
Olaf Rempel b60a0fe735 Simplify ACK handling 
TWEA bit in TWCR register needs to be cleared to send NACK.
Clear it when too many bytes were received, re-enable it after
when going idle.

Add missing state for prev. send NACK.
Catch all invalid states and reset bus.

TWINT bit needs to be set every time in ISR.
2019-11-06 13:18:53 +01:00

519 lines
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C
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/***************************************************************************
* Copyright (C) 11/2019 by Olaf Rempel *
* razzor@kopf-tisch.de *
* *
* This program 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; version 2 of the License, *
* *
* This program 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 should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
***************************************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/boot.h>
#include <avr/pgmspace.h>
#define VERSION_STRING "TWIBOOT v2.1"
#define EEPROM_SUPPORT 1
#define LED_SUPPORT 1
/* 25ms @8MHz */
#define TIMER_RELOAD (0xFF - 195)
/* 40 * 25ms */
#define TIMEOUT 40
#if LED_SUPPORT
#define LED_INIT() DDRB = ((1<<PORTB4) | (1<<PORTB5))
#define LED_RT_ON() PORTB |= (1<<PORTB4)
#define LED_RT_OFF() PORTB &= ~(1<<PORTB4)
#define LED_GN_ON() PORTB |= (1<<PORTB5)
#define LED_GN_OFF() PORTB &= ~(1<<PORTB5)
#define LED_GN_TOGGLE() PORTB ^= (1<<PORTB5)
#define LED_OFF() PORTB = 0x00
#else
#define LED_INIT()
#define LED_RT_ON()
#define LED_RT_OFF()
#define LED_GN_ON()
#define LED_GN_OFF()
#define LED_GN_TOGGLE()
#define LED_OFF()
#endif
#ifndef TWI_ADDRESS
#define TWI_ADDRESS 0x29
#endif
/* SLA+R */
#define CMD_WAIT 0x00
#define CMD_READ_VERSION 0x01
#define CMD_READ_MEMORY 0x02
/* internal mappings */
#define CMD_READ_CHIPINFO (0x10 | CMD_READ_MEMORY)
#define CMD_READ_FLASH (0x20 | CMD_READ_MEMORY)
#define CMD_READ_EEPROM (0x30 | CMD_READ_MEMORY)
#define CMD_READ_PARAMETERS (0x40 | CMD_READ_MEMORY) /* only in APP */
/* SLA+W */
#define CMD_SWITCH_APPLICATION CMD_READ_VERSION
#define CMD_WRITE_MEMORY CMD_READ_MEMORY
/* internal mappings */
#define CMD_BOOT_BOOTLOADER (0x10 | CMD_SWITCH_APPLICATION) /* only in APP */
#define CMD_BOOT_APPLICATION (0x20 | CMD_SWITCH_APPLICATION)
#define CMD_WRITE_CHIPINFO (0x10 | CMD_WRITE_MEMORY) /* invalid */
#define CMD_WRITE_FLASH (0x20 | CMD_WRITE_MEMORY)
#define CMD_WRITE_EEPROM (0x30 | CMD_WRITE_MEMORY)
#define CMD_WRITE_PARAMETERS (0x40 | CMD_WRITE_MEMORY) /* only in APP */
/* CMD_SWITCH_APPLICATION parameter */
#define BOOTTYPE_BOOTLOADER 0x00 /* only in APP */
#define BOOTTYPE_APPLICATION 0x80
/* CMD_{READ|WRITE}_* parameter */
#define MEMTYPE_CHIPINFO 0x00
#define MEMTYPE_FLASH 0x01
#define MEMTYPE_EEPROM 0x02
#define MEMTYPE_PARAMETERS 0x03 /* only in APP */
/*
* LED_GN flashes with 20Hz (while bootloader is running)
* LED_RT flashes on TWI activity
*
* bootloader twi-protocol:
* - abort boot timeout:
* SLA+W, 0x00, STO
*
* - show bootloader version
* SLA+W, 0x01, SLA+R, {16 bytes}, STO
*
* - start application
* SLA+W, 0x01, 0x80, STO
*
* - read chip info: 3byte signature, 1byte page size, 2byte flash size, 2byte eeprom size
* SLA+W, 0x02, 0x00, 0x00, 0x00, SLA+R, {8 bytes}, STO
*
* - read one (or more) flash bytes
* SLA+W, 0x02, 0x01, addrh, addrl, SLA+R, {* bytes}, STO
*
* - read one (or more) eeprom bytes
* SLA+W, 0x02, 0x02, addrh, addrl, SLA+R, {* bytes}, STO
*
* - write one flash page
* SLA+W, 0x02, 0x01, addrh, addrl, {* bytes}, STO
*
* - write one (or more) eeprom bytes
* SLA+W, 0x02, 0x02, addrh, addrl, {* bytes}, STO
*/
const static uint8_t info[16] = VERSION_STRING;
const static uint8_t chipinfo[8] = {
SIGNATURE_0, SIGNATURE_1, SIGNATURE_2,
SPM_PAGESIZE,
(BOOTLOADER_START >> 8) & 0xFF,
BOOTLOADER_START & 0xFF,
#if (EEPROM_SUPPORT)
((E2END +1) >> 8 & 0xFF),
(E2END +1) & 0xFF
#else
0x00, 0x00
#endif
};
/* wait 40 * 25ms = 1s */
static uint8_t boot_timeout = TIMEOUT;
volatile static uint8_t cmd = CMD_WAIT;
/* flash buffer */
static uint8_t buf[SPM_PAGESIZE];
static uint16_t addr;
/* *************************************************************************
* write_flash_page
* ************************************************************************* */
static void write_flash_page(void)
{
uint16_t pagestart = addr;
uint8_t size = SPM_PAGESIZE;
uint8_t *p = buf;
if (pagestart >= BOOTLOADER_START)
{
return;
}
boot_page_erase(pagestart);
boot_spm_busy_wait();
do {
uint16_t data = *p++;
data |= *p++ << 8;
boot_page_fill(addr, data);
addr += 2;
size -= 2;
} while (size);
boot_page_write(pagestart);
boot_spm_busy_wait();
boot_rww_enable();
} /* write_flash_page */
#if (EEPROM_SUPPORT)
/* *************************************************************************
* read_eeprom_byte
* ************************************************************************* */
static uint8_t read_eeprom_byte(void)
{
EEARL = addr;
EEARH = (addr >> 8);
EECR |= (1<<EERE);
addr++;
return EEDR;
} /* read_eeprom_byte */
/* *************************************************************************
* write_eeprom_byte
* ************************************************************************* */
static void write_eeprom_byte(uint8_t val)
{
EEARL = addr;
EEARH = (addr >> 8);
EEDR = val;
addr++;
#if defined (__AVR_ATmega8__)
EECR |= (1<<EEMWE);
EECR |= (1<<EEWE);
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
EECR |= (1<<EEMPE);
EECR |= (1<<EEPE);
#endif
eeprom_busy_wait();
} /* write_eeprom_byte */
#endif /* EEPROM_SUPPORT */
/* *************************************************************************
* TWI_data_write
* ************************************************************************* */
static uint8_t TWI_data_write(uint8_t bcnt, uint8_t data)
{
uint8_t ack = 0x01;
switch (bcnt)
{
case 0:
switch (data)
{
case CMD_SWITCH_APPLICATION:
case CMD_WRITE_MEMORY:
/* no break */
case CMD_WAIT:
/* abort countdown */
boot_timeout = 0;
break;
default:
/* boot app now */
cmd = CMD_BOOT_APPLICATION;
ack = 0x00;
break;
}
cmd = data;
break;
case 1:
switch (cmd)
{
case CMD_SWITCH_APPLICATION:
if (data == BOOTTYPE_APPLICATION)
{
cmd = CMD_BOOT_APPLICATION;
}
ack = 0x00;
break;
case CMD_WRITE_MEMORY:
if (data == MEMTYPE_CHIPINFO)
{
cmd = CMD_WRITE_CHIPINFO;
}
else if (data == MEMTYPE_FLASH)
{
cmd = CMD_WRITE_FLASH;
}
#if (EEPROM_SUPPORT)
else if (data == MEMTYPE_EEPROM)
{
cmd = CMD_WRITE_EEPROM;
}
#endif /* (EEPROM_SUPPORT) */
else
{
ack = 0x00;
}
break;
default:
ack = 0x00;
break;
}
break;
case 2:
case 3:
addr <<= 8;
addr |= data;
break;
default:
switch (cmd)
{
case CMD_WRITE_FLASH:
buf[bcnt -4] = data;
if (bcnt >= sizeof(buf) +3)
{
write_flash_page();
ack = 0x00;
}
break;
#if (EEPROM_SUPPORT)
case CMD_WRITE_EEPROM:
write_eeprom_byte(data);
break;
#endif /* (EEPROM_SUPPORT) */
default:
ack = 0x00;
break;
}
break;
}
return ack;
} /* TWI_data_write */
/* *************************************************************************
* TWI_data_read
* ************************************************************************* */
static uint8_t TWI_data_read(uint8_t bcnt)
{
uint8_t data;
switch (cmd)
{
case CMD_READ_VERSION:
bcnt %= sizeof(info);
data = info[bcnt];
break;
case CMD_READ_CHIPINFO:
bcnt %= sizeof(chipinfo);
data = chipinfo[bcnt];
break;
case CMD_READ_FLASH:
data = pgm_read_byte_near(addr++);
break;
#if (EEPROM_SUPPORT)
case CMD_READ_EEPROM:
data = read_eeprom_byte();
break;
#endif /* (EEPROM_SUPPORT) */
default:
data = 0xFF;
break;
}
return data;
} /* TWI_data_read */
/* *************************************************************************
* TWI_vect
* ************************************************************************* */
ISR(TWI_vect)
{
static uint8_t bcnt;
uint8_t control = TWCR;
switch (TWSR & 0xF8)
{
/* SLA+W received, ACK returned -> receive data and ACK */
case 0x60:
bcnt = 0;
LED_RT_ON();
break;
/* prev. SLA+W, data received, ACK returned -> receive data and ACK */
case 0x80:
if (TWI_data_write(bcnt++, TWDR) == 0x00)
{
control &= ~(1<<TWEA);
bcnt = 0;
}
break;
/* SLA+R received, ACK returned -> send data */
case 0xA8:
bcnt = 0;
LED_RT_ON();
/* prev. SLA+R, data sent, ACK returned -> send data */
case 0xB8:
TWDR = TWI_data_read(bcnt++);
break;
/* prev. SLA+W, data received, NACK returned -> IDLE */
case 0x88:
/* STOP or repeated START -> IDLE */
case 0xA0:
/* prev. SLA+R, data sent, NACK returned -> IDLE */
case 0xC0:
LED_RT_OFF();
control |= (1<<TWEA);
break;
/* illegal state(s) -> reset hardware */
default:
control |= (1<<TWSTO);
break;
}
TWCR = (1<<TWINT) | control;
} /* TWI_vect */
/* *************************************************************************
* TIMER0_OVF_vect
* ************************************************************************* */
ISR(TIMER0_OVF_vect)
{
/* restart timer */
TCNT0 = TIMER_RELOAD;
/* blink LED while running */
LED_GN_TOGGLE();
/* count down for app-boot */
if (boot_timeout > 1)
{
boot_timeout--;
}
else if (boot_timeout == 1)
{
/* trigger app-boot */
cmd = CMD_BOOT_APPLICATION;
}
} /* TIMER0_OVF_vect */
static void (*jump_to_app)(void) __attribute__ ((noreturn)) = 0x0000;
/*
* For newer devices the watchdog timer remains active even after a
* system reset. So disable it as soon as possible.
* automagically called on startup
*/
#if defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
/* *************************************************************************
* disable_wdt_timer
* ************************************************************************* */
void disable_wdt_timer(void) __attribute__((naked, section(".init3")));
void disable_wdt_timer(void)
{
MCUSR = 0;
WDTCSR = (1<<WDCE) | (1<<WDE);
WDTCSR = (0<<WDE);
} /* disable_wdt_timer */
#endif
/* *************************************************************************
* main
* ************************************************************************* */
int main(void) __attribute__ ((noreturn));
int main(void)
{
LED_INIT();
LED_GN_ON();
/* move interrupt-vectors to bootloader */
/* timer0: running with F_CPU/1024, OVF interrupt */
#if defined (__AVR_ATmega8__)
GICR = (1<<IVCE);
GICR = (1<<IVSEL);
TCCR0 = (1<<CS02) | (1<<CS00);
TIMSK = (1<<TOIE0);
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
MCUCR = (1<<IVCE);
MCUCR = (1<<IVSEL);
TCCR0B = (1<<CS02) | (1<<CS00);
TIMSK0 = (1<<TOIE0);
#endif
/* TWI init: set address, auto ACKs with interrupts */
TWAR = (TWI_ADDRESS<<1);
TWCR = (1<<TWEA) | (1<<TWEN) | (1<<TWIE);
sei();
while (cmd != CMD_BOOT_APPLICATION);
cli();
/* Disable TWI but keep address! */
TWCR = 0x00;
/* disable timer0 */
/* move interrupt vectors back to application */
#if defined (__AVR_ATmega8__)
TCCR0 = 0x00;
TIMSK = 0x00;
GICR = (1<<IVCE);
GICR = (0<<IVSEL);
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
TIMSK0 = 0x00;
TCCR0B = 0x00;
MCUCR = (1<<IVCE);
MCUCR = (0<<IVSEL);
#endif
LED_OFF();
uint16_t wait = 0x0000;
do {
__asm volatile ("nop");
} while (--wait);
jump_to_app();
} /* main */
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