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Author SHA1 Message Date
Olaf Rempel fc61d39288 Do not use IRQs and remove vector table
Do not use ISRs and poll for interrupt flags in the main loop.
No need for moving vector table into bootloader and back.

Remove vector table by adding LDFLAGS = -nostartfiles.
Manually add some code which is now removed, but still needed by C
runtime:
- make sure that r1 is 0x00 (zero register).
- on some MCUs the stack pointer is not initialized correctly after
reset.
- main() need to be placed in special section .init9 to be called at all.

Not sure why the BSS and DATA segment are still initialized.

This change is heavily based on the optiboot bootloader.
2019-11-06 13:18:53 +01:00
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
Olaf Rempel eee017dedf Split TWI handling into read/write functions 2019-11-06 13:18:53 +01:00
Olaf Rempel 1418971648 Remove MCU type from version string 2019-11-06 13:18:53 +01:00
Olaf Rempel 5ba6367a37 Get signature bytes from system headers 2019-11-06 13:18:53 +01:00
Olaf Rempel f4ef7a7b1e Update code style
Update indention to spaces
Fix comments
Add README.md and GPL-2 LICENSE files
2019-11-06 13:18:53 +01:00
4 changed files with 754 additions and 328 deletions

262
LICENSE Normal file
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@ -0,0 +1,262 @@
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@ -16,7 +16,9 @@ AVRDUDE_PROG := -c avr910 -b 115200 -P /dev/ttyUSB0
# ---------------------------------------------------------------------------
ifeq ($(MCU), atmega8)
# (8Mhz internal RC-Osz., 2.7V BOD)
# atmega8:
# Fuse L: 0x84 (8Mhz internal RC-Osz., 2.7V BOD)
# Fuse H: 0xda (512 words bootloader)
AVRDUDE_MCU=m8
AVRDUDE_FUSES=lfuse:w:0x84:m hfuse:w:0xda:m
@ -24,7 +26,10 @@ BOOTLOADER_START=0x1C00
endif
ifeq ($(MCU), atmega88)
# (8Mhz internal RC-Osz., 2.7V BOD)
# atmega88:
# Fuse L: 0xc2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdd (2.7V BOD)
# Fuse E: 0xfa (512 words bootloader)
AVRDUDE_MCU=m88
AVRDUDE_FUSES=lfuse:w:0xc2:m hfuse:w:0xdd:m efuse:w:0xfa:m
@ -32,7 +37,10 @@ BOOTLOADER_START=0x1C00
endif
ifeq ($(MCU), atmega168)
# (8Mhz internal RC-Osz., 2.7V BOD)
# atmega168:
# Fuse L: 0xc2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdd (2.7V BOD)
# Fuse E: 0xfa (512 words bootloader)
AVRDUDE_MCU=m168 -F
AVRDUDE_FUSES=lfuse:w:0xc2:m hfuse:w:0xdd:m efuse:w:0xfa:m
@ -40,7 +48,10 @@ BOOTLOADER_START=0x3C00
endif
ifeq ($(MCU), atmega328p)
# (8Mhz internal RC-Osz., 2.7V BOD)
# atmega328p:
# Fuse L: 0xc2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdc (512 words bootloader)
# Fuse E: 0xfd (2.7V BOD)
AVRDUDE_MCU=m328p -F
AVRDUDE_FUSES=lfuse:w:0xc2:m hfuse:w:0xdc:m efuse:w:0xfd:m
@ -52,6 +63,7 @@ endif
CFLAGS = -pipe -g -Os -mmcu=$(MCU) -Wall -fdata-sections -ffunction-sections
CFLAGS += -Wa,-adhlns=$(*F).lst -DBOOTLOADER_START=$(BOOTLOADER_START)
LDFLAGS = -Wl,-Map,$(@:.elf=.map),--cref,--relax,--gc-sections,--section-start=.text=$(BOOTLOADER_START)
LDFLAGS += -nostartfiles
# ---------------------------------------------------------------------------

95
README.md Normal file
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@ -0,0 +1,95 @@
# twiboot - a TWI / I2C bootloader for AVR MCUs ##
twiboot is a simple/small bootloader for AVR MCUs with integrated TWI peripheral written in C.
It was originally created to update I2C controlled BLMCs (Brushless Motor Controller) without an AVR ISP adapter.
twiboot acts as a slave device on a TWI/I2C bus and allows reading/writing of the internal flash memory.
As a compile time option twiboot also allows reading/writing of the whole internal EEPROM memory.
The bootloader is not able to update itself (only application flash memory region accessible).
Currently the following AVR MCUs are supported:
AVR MCU | Flash bytes used (.text + .data) | Bootloader region size
--- | --- | ---
atmega8 | 724 (0x2D4) | 512 words
atmega88 | 744 (0x2E8) | 512 words
atmega168 | 744 (0x2E8) | 512 words
atmega328p | 744 (0x2E8) | 512 words
(Compiled on Ubuntu 18.04 LTS (gcc 5.4.0 / avr-libc 2.0.0) with EEPROM and LED support)
## Operation ##
twiboot is installed in the bootloader memory region and executed directly after reset (BOOTRST fuse is programmed).
While running, twiboot configures the TWI peripheral as slave device and waits for valid protocol messages
directed to its address on the TWI/I2C bus. The slave address is configured during compile time of twiboot.
When receiving no messages for 1000ms after reset, the bootloader exits and executes the main application at address 0x0000.
A TWI/I2C master can use the protocol to
- abort the boot timeout
- query information about the device (bootloader version, AVR signature bytes, flash/eeprom size, flash page size)
- read internal flash / eeprom memory (byte wise)
- write the internal flash (page wise)
- write the internal eeprom (byte wise)
- exit the bootloader and start the application
As a compile time option twiboot can output its state with two LEDs.
One LED will flash with a frequency of 20Hz while twiboot is active (including boot wait time).
A second LED will flash when the bootloader is addressed on the TWI/I2C bus.
## Build and install twiboot ##
twiboot uses gcc, avr-libc and GNU Make for building, avrdude is used for flashing the MCU.
The build and install procedures are only tested under linux.
The selection of the target MCU and the programming interface can be found in the Makefile,
TWI/I2C slave address and optional components (EEPROM / LED support) are configured
in the main.c source.
To build twiboot for the selected target:
``` shell
$ make
```
To install (flash download) twiboot with avrdude on the target:
``` shell
$ make install
```
Set AVR fuses with avrdude on the target (internal RC-Osz, enable BOD, enable BOOTRST):
``` shell
$ make fuses
```
## TWI/I2C Protocol ##
A TWI/I2C master can use the following protocol for accessing the bootloader.
Function | TWI/I2C data | Comment
--- | --- | ---
Abort boot timeout | **SLA+W**, 0x00, **STO** |
Show bootloader version | **SLA+W**, 0x01, **SLA+R**, {16 bytes}, **STO** | ASCII, not null terminated
Start application | **SLA+W**, 0x01, 0x80, **STO** |
Read chip info | **SLA+W**, 0x02, 0x00, 0x00, 0x00, **SLA+R**, {8 bytes}, **STO** | 3byte signature, 1byte page size, 2byte flash size, 2byte eeprom size
Read 1+ flash bytes | **SLA+W**, 0x02, 0x01, addrh, addrl, **SLA+R**, {* bytes}, **STO** |
Read 1+ eeprom bytes | **SLA+W**, 0x02, 0x02, addrh, addrl, **SLA+R**, {* bytes}, **STO** |
Write one flash page | **SLA+W**, 0x02, 0x01, addrh, addrl, {* bytes}, **STO** | page size as indicated in chip info
Write 1+ eeprom bytes | **SLA+W**, 0x02, 0x02, addrh, addrl, {* bytes}, **STO** |
**SLA+R** means Start Condition, Slave Address, Read Access
**SLA+W** means Start Condition, Slave Address, Write Access
**STO** means Stop Condition
The multiboot_tool repository contains a simple linux application that uses
this protocol to access the bootloader over linux i2c device.
## Development ##
Issue reports, feature requests, patches or simply success stories are much appreciated.
## Roadmap ##
Some ideas that I want to investigate / implement in twiboot:
- find a way to not rely on TWI clock stretching during write access
- support AVR TINYs (USI peripheral, no bootloader fuse, no Read-While-Write flash)

705
main.c
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@ -1,5 +1,5 @@
/***************************************************************************
* Copyright (C) 08/2010 by Olaf Rempel *
* Copyright (C) 11/2019 by Olaf Rempel *
* razzor@kopf-tisch.de *
* *
* This program is free software; you can redistribute it and/or modify *
@ -21,64 +21,24 @@
#include <avr/boot.h>
#include <avr/pgmspace.h>
/*
* atmega8:
* Fuse H: 0xda (512 words bootloader)
* Fuse L: 0x84 (8Mhz internal RC-Osz., 2.7V BOD)
*
* atmega88:
* Fuse E: 0xfa (512 words bootloader)
* Fuse H: 0xdd (2.7V BOD)
* Fuse L: 0xc2 (8Mhz internal RC-Osz.)
*
* atmega168:
* Fuse E: 0xfa (512 words bootloader)
* Fuse H: 0xdd (2.7V BOD)
* Fuse L: 0xc2 (8Mhz internal RC-Osz.)
*
* atmega328p:
* Fuse E: 0xfd (2.7V BOD)
* Fuse H: 0xdc (512 words bootloader)
* Fuse L: 0xc2 (8Mhz internal RC-Osz.)
*/
#if defined (__AVR_ATmega8__)
#define VERSION_STRING "TWIBOOT m8v2.1"
#define SIGNATURE_BYTES 0x1E, 0x93, 0x07
#elif defined (__AVR_ATmega88__)
#define VERSION_STRING "TWIBOOT m88v2.1"
#define SIGNATURE_BYTES 0x1E, 0x93, 0x0A
#elif defined (__AVR_ATmega168__)
#define VERSION_STRING "TWIBOOT m168v2.1"
#define SIGNATURE_BYTES 0x1E, 0x94, 0x06
#elif defined (__AVR_ATmega328P__)
#define VERSION_STRING "TWIBOOTm328pv2.1"
#define SIGNATURE_BYTES 0x1E, 0x95, 0x0F
#else
#error MCU not supported
#endif
#define EEPROM_SUPPORT 1
#define LED_SUPPORT 1
#define VERSION_STRING "TWIBOOT v2.1"
#define EEPROM_SUPPORT 1
#define LED_SUPPORT 1
/* 25ms @8MHz */
#define TIMER_RELOAD (0xFF - 195)
#define TIMER_RELOAD (0xFF - 195)
/* 40 * 25ms */
#define TIMEOUT 40
#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
#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()
@ -90,43 +50,43 @@
#endif
#ifndef TWI_ADDRESS
#define TWI_ADDRESS 0x29
#define TWI_ADDRESS 0x29
#endif
/* SLA+R */
#define CMD_WAIT 0x00
#define CMD_READ_VERSION 0x01
#define CMD_READ_MEMORY 0x02
#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 */
#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
#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 */
#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
#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 */
#define MEMTYPE_CHIPINFO 0x00
#define MEMTYPE_FLASH 0x01
#define MEMTYPE_EEPROM 0x02
#define MEMTYPE_PARAMETERS 0x03 /* only in APP */
/*
* LED_GN blinks with 20Hz (while bootloader is running)
* LED_RT blinks on TWI activity
* LED_GN flashes with 20Hz (while bootloader is running)
* LED_RT flashes on TWI activity
*
* bootloader twi-protocol:
* - abort boot timeout:
@ -139,7 +99,7 @@
* 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, {4 bytes}, STO
* 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
@ -147,8 +107,8 @@
* - read one (or more) eeprom bytes
* SLA+W, 0x02, 0x02, addrh, addrl, SLA+R, {* bytes}, STO
*
* - write one flash page (64bytes on mega8)
* SLA+W, 0x02, 0x01, addrh, addrl, {64 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
@ -156,327 +116,424 @@
const static uint8_t info[16] = VERSION_STRING;
const static uint8_t chipinfo[8] = {
SIGNATURE_BYTES,
SIGNATURE_0, SIGNATURE_1, SIGNATURE_2,
SPM_PAGESIZE,
SPM_PAGESIZE,
(BOOTLOADER_START >> 8) & 0xFF,
BOOTLOADER_START & 0xFF,
(BOOTLOADER_START >> 8) & 0xFF,
BOOTLOADER_START & 0xFF,
#if (EEPROM_SUPPORT)
((E2END +1) >> 8 & 0xFF),
(E2END +1) & 0xFF
((E2END +1) >> 8 & 0xFF),
(E2END +1) & 0xFF
#else
0x00, 0x00
0x00, 0x00
#endif
};
/* wait 40 * 25ms = 1s */
static uint8_t boot_timeout = TIMEOUT;
volatile static uint8_t cmd = CMD_WAIT;
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;
uint16_t pagestart = addr;
uint8_t size = SPM_PAGESIZE;
uint8_t *p = buf;
if (pagestart >= BOOTLOADER_START)
return;
if (pagestart >= BOOTLOADER_START)
{
return;
}
boot_page_erase(pagestart);
boot_spm_busy_wait();
boot_page_erase(pagestart);
boot_spm_busy_wait();
do {
uint16_t data = *p++;
data |= *p++ << 8;
boot_page_fill(addr, data);
do {
uint16_t data = *p++;
data |= *p++ << 8;
boot_page_fill(addr, data);
addr += 2;
size -= 2;
} while (size);
addr += 2;
size -= 2;
} while (size);
boot_page_write(pagestart);
boot_spm_busy_wait();
boot_rww_enable();
} /* write_flash_page */
boot_page_write(pagestart);
boot_spm_busy_wait();
boot_rww_enable();
}
#if (EEPROM_SUPPORT)
/* *************************************************************************
* read_eeprom_byte
* ************************************************************************* */
static uint8_t read_eeprom_byte(void)
{
EEARL = addr;
EEARH = (addr >> 8);
EECR |= (1<<EERE);
addr++;
return EEDR;
}
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++;
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);
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();
}
eeprom_busy_wait();
} /* write_eeprom_byte */
#endif /* EEPROM_SUPPORT */
ISR(TWI_vect)
/* *************************************************************************
* TWI_data_write
* ************************************************************************* */
static uint8_t TWI_data_write(uint8_t bcnt, uint8_t data)
{
static uint8_t bcnt;
uint8_t data;
uint8_t ack = (1<<TWEA);
uint8_t ack = 0x01;
switch (TWSR & 0xF8) {
/* SLA+W received, ACK returned -> receive data and ACK */
case 0x60:
bcnt = 0;
LED_RT_ON();
TWCR |= (1<<TWINT) | (1<<TWEA);
break;
switch (bcnt)
{
case 0:
switch (data)
{
case CMD_SWITCH_APPLICATION:
case CMD_WRITE_MEMORY:
/* no break */
/* prev. SLA+W, data received, ACK returned -> receive data and ACK */
case 0x80:
data = TWDR;
switch (bcnt) {
case 0:
switch (data) {
case CMD_SWITCH_APPLICATION:
case CMD_WRITE_MEMORY:
bcnt++;
/* no break */
case CMD_WAIT:
/* abort countdown */
boot_timeout = 0;
break;
case CMD_WAIT:
/* abort countdown */
boot_timeout = 0;
break;
default:
/* boot app now */
cmd = CMD_BOOT_APPLICATION;
ack = 0x00;
break;
}
default:
/* boot app now */
cmd = CMD_BOOT_APPLICATION;
ack = (0<<TWEA);
break;
}
cmd = data;
break;
cmd = data;
break;
case 1:
switch (cmd) {
case CMD_SWITCH_APPLICATION:
if (data == BOOTTYPE_APPLICATION) {
cmd = CMD_BOOT_APPLICATION;
}
ack = (0<<TWEA);
break;
case 1:
switch (cmd)
{
case CMD_SWITCH_APPLICATION:
if (data == BOOTTYPE_APPLICATION)
{
cmd = CMD_BOOT_APPLICATION;
}
case CMD_WRITE_MEMORY:
bcnt++;
if (data == MEMTYPE_CHIPINFO) {
cmd = CMD_WRITE_CHIPINFO;
ack = 0x00;
break;
} else if (data == MEMTYPE_FLASH) {
cmd = CMD_WRITE_FLASH;
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
} else {
ack = (0<<TWEA);
}
break;
else if (data == MEMTYPE_EEPROM)
{
cmd = CMD_WRITE_EEPROM;
}
#endif /* (EEPROM_SUPPORT) */
else
{
ack = 0x00;
}
break;
default:
ack = (0<<TWEA);
break;
}
break;
default:
ack = 0x00;
break;
}
break;
case 2:
case 3:
addr <<= 8;
addr |= data;
bcnt++;
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;
default:
switch (cmd) {
case CMD_WRITE_FLASH:
buf[bcnt -4] = data;
if (bcnt < sizeof(buf) +3) {
bcnt++;
} else {
write_flash_page();
ack = (0<<TWEA);
}
break;
#if (EEPROM_SUPPORT)
case CMD_WRITE_EEPROM:
write_eeprom_byte(data);
bcnt++;
break;
#endif
default:
ack = (0<<TWEA);
break;
}
break;
}
case CMD_WRITE_EEPROM:
write_eeprom_byte(data);
break;
#endif /* (EEPROM_SUPPORT) */
if (ack == 0x00)
bcnt = 0;
default:
ack = 0x00;
break;
}
break;
}
TWCR |= (1<<TWINT) | ack;
break;
return ack;
} /* TWI_data_write */
/* 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:
switch (cmd) {
case CMD_READ_VERSION:
data = info[bcnt++];
bcnt %= sizeof(info);
break;
case CMD_READ_CHIPINFO:
data = chipinfo[bcnt++];
bcnt %= sizeof(chipinfo);
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
default:
data = 0xFF;
break;
}
TWDR = data;
TWCR |= (1<<TWINT) | (1<<TWEA);
break;
/* STOP or repeated START */
case 0xA0:
/* data sent, NACK returned */
case 0xC0:
LED_RT_OFF();
TWCR |= (1<<TWINT) | (1<<TWEA);
break;
/* illegal state -> reset hardware */
case 0xF8:
TWCR |= (1<<TWINT) | (1<<TWSTO) | (1<<TWEA);
break;
}
}
ISR(TIMER0_OVF_vect)
/* *************************************************************************
* TWI_data_read
* ************************************************************************* */
static uint8_t TWI_data_read(uint8_t bcnt)
{
/* restart timer */
TCNT0 = TIMER_RELOAD;
uint8_t data;
/* blink LED while running */
LED_GN_TOGGLE();
switch (cmd)
{
case CMD_READ_VERSION:
bcnt %= sizeof(info);
data = info[bcnt];
break;
/* count down for app-boot */
if (boot_timeout > 1)
boot_timeout--;
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
* ************************************************************************* */
static void TWI_vect(void)
{
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
* ************************************************************************* */
static void TIMER0_OVF_vect(void)
{
/* 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 */
/* trigger app-boot */
else if (boot_timeout == 1)
cmd = CMD_BOOT_APPLICATION;
}
static void (*jump_to_app)(void) __attribute__ ((noreturn)) = 0x0000;
/* *************************************************************************
* init1
* ************************************************************************* */
void init1(void) __attribute__((naked, section(".init1")));
void init1(void)
{
/* make sure r1 is 0x00 */
asm volatile ("clr __zero_reg__");
/* on some MCUs the stack pointer defaults NOT to RAMEND */
#if defined(__AVR_ATmega8__) || defined(__AVR_ATmega8515__) || \
defined(__AVR_ATmega8535__) || defined (__AVR_ATmega16__) || \
defined (__AVR_ATmega32__) || defined (__AVR_ATmega64__) || \
defined (__AVR_ATmega128__) || defined (__AVR_ATmega162__)
SP = RAMEND;
#endif
} /* init1 */
/*
* For newer devices (mega88) the watchdog timer remains active even after a
* 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__)
#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);
}
MCUSR = 0;
WDTCSR = (1<<WDCE) | (1<<WDE);
WDTCSR = (0<<WDE);
} /* disable_wdt_timer */
#endif
int main(void) __attribute__ ((noreturn));
/* *************************************************************************
* main
* ************************************************************************* */
int main(void) __attribute__ ((OS_main, section (".init9")));
int main(void)
{
LED_INIT();
LED_GN_ON();
LED_INIT();
LED_GN_ON();
/* move interrupt-vectors to bootloader */
/* timer0: running with F_CPU/1024, OVF interrupt */
/* timer0: running with F_CPU/1024 */
#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);
TCCR0 = (1<<CS02) | (1<<CS00);
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
TCCR0B = (1<<CS02) | (1<<CS00);
#endif
/* TWI init: set address, auto ACKs with interrupts */
TWAR = (TWI_ADDRESS<<1);
TWCR = (1<<TWEA) | (1<<TWEN) | (1<<TWIE);
/* TWI init: set address, auto ACKs */
TWAR = (TWI_ADDRESS<<1);
TWCR = (1<<TWEA) | (1<<TWEN);
sei();
while (cmd != CMD_BOOT_APPLICATION);
cli();
while (cmd != CMD_BOOT_APPLICATION)
{
if (TWCR & (1<<TWINT))
{
TWI_vect();
}
/* Disable TWI but keep address! */
TWCR = 0x00;
/* disable timer0 */
/* move interrupt vectors back to application */
#if defined (__AVR_ATmega8__)
TCCR0 = 0x00;
TIMSK = 0x00;
if (TIFR & (1<<TOV0))
{
TIMER0_OVF_vect();
TIFR = (1<<TOV0);
}
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
if (TIFR0 & (1<<TOV0))
{
TIMER0_OVF_vect();
TIFR0 = (1<<TOV0);
}
#endif
}
GICR = (1<<IVCE);
GICR = (0<<IVSEL);
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || defined (__AVR_ATmega328P__)
TIMSK0 = 0x00;
TCCR0B = 0x00;
/* Disable TWI but keep address! */
TWCR = 0x00;
MCUCR = (1<<IVCE);
MCUCR = (0<<IVSEL);
/* disable timer0 */
#if defined (__AVR_ATmega8__)
TCCR0 = 0x00;
#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__) || \
defined (__AVR_ATmega328P__)
TCCR0B = 0x00;
#endif
LED_OFF();
LED_OFF();
uint16_t wait = 0x0000;
do {
__asm volatile ("nop");
} while (--wait);
uint16_t wait = 0x0000;
do {
__asm volatile ("nop");
} while (--wait);
jump_to_app();
}
jump_to_app();
} /* main */