when using the Atmel-ICE you have to export AVR_DEBUGDEVICE=-edbg. Note If you are using a different debugger than the AVR Dragon, you have to export the AVR_DEBUGDEVICE environment variable to the required flag to pass to AVaRICE, e.g. Perform a cold boot and the ATmega328P will have debugWIRE enabled again. If this fails after flashing the ATmega328P, it is like due to debugWIRE being temporary disabled by avrdude in order to use the ISP feature. Once the MCU is connected and debugWIRE is enabled via the fuse settings, you can start debugging via: make debug So only enable debugWIRE if you have an AVR DRagon or other means to disable debugWIRE later on again.įor debugging, the ATmega328P needs to be connected to the AVR Dragon in the very same way it needs to be connected for programming (see above). The AVR Dragon can temporary disable the debugWIRE interface via a debugWIRE command and avrdude will do so when debugWIRE is used. Warning As the reset pin is repurposed for debugWIRE, a regular ISP will not be able to disable the debugWIRE interface anymore. You can disable it again via: avrdude -c -p m328p -U hfuse:w:0xd9:m with dragon_isp if you use the AVR Dragon): avrdude -c -p m328p -U hfuse:w:0x99:m In order to enable debugWIRE run (replace with the programmer you use, e.g. Thus, every breakpoint hit cause two flash cycles to be performed, which not only results in a slow debugging experience, but also causes significant wear. Once the breakpoint is hit, the break instruction is overwritten with the original instruction. If you set breakpoints, the AVR Dragon will transparently replace the instruction to break upon with a break instruction. The hardware breakpoint is used for single-stepping. Compared to the ATmega MCUs with JTAG interface the debug facilities are however significantly reduced: Only a single hardware breakpoint and no watchpoints are supported. with the AVR Dragon and AVaRICE you can debug the ATmega328P using the debugWIRE interface. Usually everything between 3.3 V and 5 V should work.Į.g. Please note that the supply voltage should be compatible with the logic level of the TTL adapter. To use the programmer instead, run make BOARD=atmega328p PROGRAMMER= flashĬonnect a TTL adapter with pins 2/RXD and 3/TXD an run make BOARD=atmega328p term When using the usbtiny (or one of the super cheap clones) running make BOARD=atmega328p flash Connect the programmer as follows: ISCP pin In order to flash the ATmega328P without a bootloader, an ICSP programmer is needed. For more details, refer to the official datasheet. At 1 MHz core clock a supply voltage of 1.8V is possible resulting in an active supply current of less than 0.3 mA (about 0.5 mW power consumption). The lowest possible supply voltage at 8 MHz is 2.7V (with some safety margin), which results in an active supply current of less than 3 mA (about 8 mW power consumption) according to the datasheet. However, higher clock frequencies require higher supply voltages for reliable operation. Thus, lower power consumption can be achieved by using a lower supply voltage. Relation Between Supply Voltage, Clock Frequency and Power ConsumptionĪ higher supply voltage results in a higher current drawn. Refer to the datasheet on how to configure the ATmega328p to use an external crystal, an external clock source or the clock divider. 1000000 for 1MHz), this core clock can be changed easily. This "board" is configured to use 8MHz as core clock, so that the ATmega328p runs at the highest frequency possible without external clock sources.īy setting the environment variable ATMEGA328P_CLOCK to a custom frequency in Hz (e.g. It will not be needed anymore after the clock device has been disabled.) The -B 32 might be needed on some ISP programmers to communicate with slow ATmega MCUs. (Replace usbtiny with the ISP programmer you are using. This can be done like this: avrdude -c usbtiny -p m328p -B 32 -U lfuse:w:0xe2:m By clearing the CKDIV8 fuse the clock divider can be disabled to operate the ATmega328p at 8MHz without an external clock source. By default the fuses are configured to use the internal 8MHz oscillator and a clock divider resulting in a clock speed of 1MHz. The ATmega328p has two internal oscillators clocked at 8MHz and at 128kHz that allow it to be operated without any external clock source or crystal. All credit for above pinout image goes to
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