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v2.0 ... master

Author SHA1 Message Date
559a403836 Do not reply with NAK on last byte
At least the bcm2835 (Raspberry Pi 3) I2C/SMBus master has problems
when replying with a NAK to the last byte written to a slave device.

Fix this by replying with NAK one byte later.
2021-02-20 22:12:01 +01:00
baf5a895b5 Update README 2020-10-26 19:53:43 +01:00
f4952aaa63 Implement a virtual bootloader section
- patch reset vector while programming flash page0
  Let the reset vector always point to the twiboot start.
- Use another (must be unused!) ISR vector to store the original
  reset vector as jump to the application.
- Cache the values for the verification read
- currently works only for devices < 8kB flash (2 byte vector entries)
- using a attiny85 as target

This change is heavily based on the optiboot bootloader.
2020-10-26 18:54:00 +01:00
9f3781a3eb Implement USI peripheral slave statemachine
- Implement a TWI slave using the USI peripheral found in AVR tiny MCUs
- using attiny85 as target (has no bootloader section!)
- USI peripheral in general needs clock stretching support from the
  master since the whole statemachine is software based.
  For now the actual writing to flash/eeprom is also done during
  clock stretching (like original twiboot implementation).
  This might be changed later.
- ACK/NAK handling is different:
  For TWI peripheral the ACK/NAK of the *next* byte has to be returned
  by TWI_data_write(). For USI peripheral the ACK/NAK of the *current*
  byte needs to be returned. For now the TWI version remains in the
  code and might be changed later.
2020-10-26 13:51:07 +01:00
df56c54697 Align identation and some cleanup 2020-10-24 22:09:34 +02:00
c5f5a74783 Increment major version
Make a major version bump since the clockstretching changes require
retries/polling and might break current master implementations.
2020-02-02 00:08:13 +01:00
964c933bf3 Do not rely on Clockstretching for writes 2020-02-02 00:03:09 +01:00
5bdbb430e7 Fix NACK handling for flash write 2020-02-01 23:59:15 +01:00
0416a2f536 Cleanup and reduce size 2020-02-01 23:58:50 +01:00
cde9bf0a5b Cleanup command names 2020-02-01 22:50:47 +01:00
05a4533cd2 Do not repeat check for every chip type 2020-02-01 22:50:22 +01:00
7e7e50ad84 Calculate timer values 2020-02-01 22:49:51 +01:00
1ff13ca69e
Fix markdown table on github 2019-11-06 13:24:46 +01:00
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
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
eee017dedf Split TWI handling into read/write functions 2019-11-06 13:18:53 +01:00
1418971648 Remove MCU type from version string 2019-11-06 13:18:53 +01:00
5ba6367a37 Get signature bytes from system headers 2019-11-06 13:18:53 +01:00
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
dd4ca2cb33 Merge pull request #2 from jlefley/atmega328p
fix comment to reflect changes in fuses
2015-03-25 09:48:04 +01:00
Jason Lefley
f58adea5d6 fix comment to reflect changes in fuses 2015-03-24 11:13:57 -07:00
bc5d45359a Fix sizeof(VERSION_STRING)
- sizeof(info) should not be increased (16->18) since the size is never
  exchanged with the I2C master. Also using a non 2^x size will result
  in bigger code since the compiler can no longer use a simple AND to
  implement the bcnt %= sizeof(info).

- when using a info[16] the firmware is small enough to fit in a 512
  word bootloader again :)
2015-03-21 09:15:43 +01:00
31d65c76d7 Merge pull request #1 from jlefley/atmega328p
Add support for atmega328p
2015-03-21 09:11:27 +01:00
Jason Lefley
89b3251dde add support for atmega328p 2015-03-18 15:28:12 -07:00
df9fb6c077 move linux tool to own repository 2014-12-26 11:37:34 +01:00
5e4b562608 update Makefile 2014-10-05 14:32:07 +02:00
ca2a0a99ae replace linux application 2012-02-11 12:44:02 +01:00
9424e20ea7 add LED macros, bump version 2011-02-20 14:40:42 +01:00
d281696895 add progressbar for dumb terminals 2011-02-20 14:40:13 +01:00
9da00855c1 some cleanup 2010-12-25 13:08:02 +01:00
7aa4456607 wait 100ms after application switch 2010-12-25 12:50:23 +01:00
3acd88c11c add small timeout after exit 2010-10-17 18:24:12 +02:00
b16b660495 fix mega8 interrupt vector switch 2010-10-17 18:23:41 +02:00
a857b3906e fix verify in linux tool 2010-10-17 18:22:38 +02:00
6244c44e65 add linux tool 2010-10-16 19:29:15 +02:00
8a98e09c46 corrections 2010-10-16 19:28:05 +02:00
b2c6dc35ce flag eeprom support 2010-08-15 17:01:06 +02:00
525c2e3701 Merge branch 'mega88' 2010-08-15 16:47:01 +02:00
f73b52bc3c multicpu support 2010-08-15 16:44:54 +02:00
a2becf91ad reduce codesize 2008-06-23 13:51:08 +02:00
5 changed files with 1258 additions and 314 deletions

1
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*.bin
*.hex
*.lst
*.lss
*.map

262
LICENSE Normal file
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130
Makefile
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PRG = twiboot
OBJ = main.o
MCU_TARGET = atmega88
OPTIMIZE = -Os
CC := avr-gcc
LD := avr-ld
OBJCOPY := avr-objcopy
OBJDUMP := avr-objdump
SIZE := avr-size
DEFS =
LIBS =
TARGET = twiboot
SOURCE = $(wildcard *.c)
# Override is only needed by avr-lib build system.
override CFLAGS = -g -Wall $(OPTIMIZE) -mmcu=$(MCU_TARGET) $(DEFS)
override LDFLAGS = -Wl,-Map,$(PRG).map,--section-start=.text=0x1C00
# select MCU
MCU = attiny85
CC = avr-gcc
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
SIZE = avr-size
AVRDUDE_PROG := -c avr910 -b 115200 -P /dev/ttyUSB0
#AVRDUDE_PROG := -c dragon_isp -P usb
all: $(PRG).elf lst text
$(SIZE) -x -A $(PRG).elf
# ---------------------------------------------------------------------------
$(PRG).elf: $(OBJ)
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
ifeq ($(MCU), atmega8)
# 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
BOOTLOADER_START=0x1C00
endif
ifeq ($(MCU), atmega88)
# atmega88:
# Fuse L: 0xc2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdd (2.7V BOD)
# Fuse E: 0xfa (512 words bootloader)
AVRDUDE_MCU=m88
AVRDUDE_FUSES=lfuse:w:0xc2:m hfuse:w:0xdd:m efuse:w:0xfa:m
BOOTLOADER_START=0x1C00
endif
ifeq ($(MCU), atmega168)
# 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
BOOTLOADER_START=0x3C00
endif
ifeq ($(MCU), atmega328p)
# atmega328p:
# Fuse L: 0xc2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdc (512 words bootloader)
# Fuse E: 0xfd (2.7V BOD)
AVRDUDE_MCU=m328p -F
AVRDUDE_FUSES=lfuse:w:0xc2:m hfuse:w:0xdc:m efuse:w:0xfd:m
BOOTLOADER_START=0x7C00
endif
ifeq ($(MCU), attiny85)
# attiny85:
# Fuse L: 0xe2 (8Mhz internal RC-Osz.)
# Fuse H: 0xdd (2.7V BOD)
# Fuse E: 0xfe (self programming enable)
AVRDUDE_MCU=t85
AVRDUDE_FUSES=lfuse:w:0xe2:m hfuse:w:0xdd:m efuse:w:0xfe:m
BOOTLOADER_START=0x1C00
CFLAGS_TARGET=-DUSE_CLOCKSTRETCH=1 -DVIRTUAL_BOOT_SECTION=1
endif
# ---------------------------------------------------------------------------
CFLAGS = -pipe -g -Os -mmcu=$(MCU) -Wall -fdata-sections -ffunction-sections
CFLAGS += -Wa,-adhlns=$(*F).lst -DBOOTLOADER_START=$(BOOTLOADER_START) $(CFLAGS_TARGET)
LDFLAGS = -Wl,-Map,$(@:.elf=.map),--cref,--relax,--gc-sections,--section-start=.text=$(BOOTLOADER_START)
LDFLAGS += -nostartfiles
# ---------------------------------------------------------------------------
$(TARGET): $(TARGET).elf
@$(SIZE) -B -x --mcu=$(MCU) $<
$(TARGET).elf: $(SOURCE:.c=.o)
@echo " Linking file: $@"
@$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^
@$(OBJDUMP) -h -S $@ > $(@:.elf=.lss)
@$(OBJCOPY) -j .text -j .data -O ihex $@ $(@:.elf=.hex)
@$(OBJCOPY) -j .text -j .data -O binary $@ $(@:.elf=.bin)
%.o: %.c $(MAKEFILE_LIST)
@echo " Building file: $<"
@$(CC) $(CFLAGS) -o $@ -c $<
clean:
rm -rf *.o *.lst *.map $(PRG).elf *.hex *.bin
rm -rf $(SOURCE:.c=.o) $(SOURCE:.c=.lst) $(addprefix $(TARGET), .elf .map .lss .hex .bin)
lst: $(PRG).lst
%.lst: %.elf
$(OBJDUMP) -h -S $< > $@
text: hex bin
hex: $(PRG).hex
bin: $(PRG).bin
%.hex: %.elf
$(OBJCOPY) -j .text -j .data -O ihex $< $@
%.bin: %.elf
$(OBJCOPY) -j .text -j .data -O binary $< $@
install: text
avrdude -c dragon_isp -P usb -p m88 -U flash:w:$(PRG).hex
install: $(TARGET).elf
avrdude $(AVRDUDE_PROG) -p $(AVRDUDE_MCU) -U flash:w:$(<:.elf=.hex)
fuses:
avrdude -c dragon_isp -P usb -p m88 -U lfuse:w:0xc2:m -U hfuse:w:0xdd:m -U efuse:w:0xfa:m
avrdude $(AVRDUDE_PROG) -p $(AVRDUDE_MCU) $(patsubst %,-U %, $(AVRDUDE_FUSES))

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# twiboot - a TWI / I2C bootloader for AVR MCUs ##
twiboot is a simple/small bootloader for AVR MCUs written in C. It uses the integrated TWI or USI peripheral of the controller to implement a I2C slave.
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 (EEPROM_SUPPORT) 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
--- | --- | ---
attiny85 | 954 (0x3BA) | 512 words
atmega8 | 786 (0x312) | 512 words
atmega88 | 810 (0x32A) | 512 words
atmega168 | 810 (0x32A) | 512 words
atmega328p | 810 (0x32A) | 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 section and executed directly after reset (BOOTRST fuse is programmed).
For MCUs without bootloader section see [Virtual bootloader section](#virtual-bootloader-section) below.
While running, twiboot configures the TWI/USI 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 (LED_SUPPORT) 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.
### Virtual Bootloader Section ###
For MCUs without bootloader section twiboot will patch the vector table on the fly during flash programming to stay active.
The reset vector is patched to execute twiboot instead of the application code.
Another vector entry will be patched to store the original entry point of the application.
This vector entry is overridden and MUST NOT be used by the application.
twiboot uses this vector to start the application after the initial timeout.
This live patching changes the content of the vector table, which would result in a verification error after programming.
To counter this kind of error, twiboot caches the original vector table entries in RAM and return those on a read command.
The real content of the vector table is only returned after a reset.
## 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** | write 0 < n < page size bytes at once
**SLA+R** means Start Condition, Slave Address, Read Access
**SLA+W** means Start Condition, Slave Address, Write Access
**STO** means Stop Condition
A flash page / eeprom write is only triggered after the Stop Condition.
During the write process twiboot will NOT acknowledge its slave address.
The multiboot_tool repository contains a simple linux application that uses
this protocol to access the bootloader over linux i2c device.
The ispprog programming adapter can also be used as a avr910/butterfly to twiboot protocol bridge.
## TWI/I2C Clockstretching ##
While a write is in progress twiboot will not respond on the TWI/I2C bus and the
TWI/I2C master needs to retry/poll the slave address until the write has completed.
As a compile time option (USE_CLOCKSTRETCH) the previous behavior of twiboot can be restored:
TWI/I2C Clockstretching is then used to inform the master of the duration of the write.
Please note that there are some TWI/I2C masters that do not support clockstretching.
## Development ##
Issue reports, feature requests, patches or simply success stories are much appreciated.

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main.c

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