Support for the Arduino Nano board. More...
Support for the Arduino Nano board.
The Arduino Nano is the cheapest member of the Arduino family. It is based on Atmel's AVR architecture and sports an ATmega328p MCU. It is like many Arduinos extensible by using shields.
|Flash||32 KiB (2 KiB reserved for the bootloader)|
|Timers||3 (2x 8bit, 1x 16bit)|
|ADCs||6 analog input pins|
|I2Cs||1 (called TWI)|
|MCU Datasheet||ATmega328p datasheet|
|Board Manual||Board Manual|
Flashing RIOT on the Arduino Nano is quite straight forward, just connect your Arduino Nano via the USB connector to your host computer and type:
make BOARD=arduino-nano flash
This should take care of everything!
We use the open
avrdude tool to write the new code into the ATmega328p's flash
You can use the Optiboot bootloader instead of the stock bootloader for faster programming. Optiboot also is smaller (512 byte instead of 2 KiB), so that 1.5 KiB more program memory is available for RIOT. Refer to the project page for instructions on how to build an flash the bootloader. Don't forgot to also update the fuse settings to set the bootloader size to 256 words (512 bytes).
Compile and flash with
make BOARD=arduino-nano ATMEGA_BOOTLOADER=optiboot flash or use
export ARDUINO_NANO_BOOTLOADER=optiboot in order to not have to specify the bootloader during compilation and flashing.
If RIOT is stuck in a reboot loop e.g. after restarting the device with the
reboot shell command, this is likely caused by an issue with the stock bootloader that can be solved by using Optiboot as bootloader instead (see above).
On-Chip Debugging on the Arduino Nano is not supported via the usual JTAG interface used in ATmega MCUs with higher pin counts, but via debugWIRE. While debugWIRE has the advantage of only using the RESET pin to transfer data, the features provided are extremely limited. If the same issue can be reproduced on an Arduino Mega2560, which supports JTAG, it will be much easier and more productive to debug your code on the Arduino Mega2560. If the bug cannot be reproduced, limited on chip debugging is possible on the Arduino Nano nonetheless.
In order to be able to use On-Chip Debugging you will need the AVR Dragon, which is the ~~cheapest~~ least expensive programmer and debugger available that supports programming via SPI ("normal ISP"), High Voltage Serial Programming, and Parallel Programming, as well as debugging via JTAG, debugWIRE, PDI and aWire. So at least can use it for just about every AVR device.
On the Arduino Nano the RESET pin of the MCU is connected to a 100 nF capacitor, which in turn is connected to the DTR pin of the FT232RL USB-UART bridge. This allows the device to be automatically reset when you connected to the board via a serial. This is particularly useful during programming via the bootloader (without external ISP programmer), as avrdude can trigger the reset and, thus, start the bootloader without the user having to press a button.
In order to use on-chip debugging, the capacitor needs however to be disconnected from the reset pin. You can either carefully de-solder it (which allows you to solder it back in after debugging), or just break it off with pinch-nose pliers (which usually destroys the capacitor, making the modification permanent). After this modification, flashing via bootloader requires a manual press on the reset button.
You need to have AVaRICE installed. Some distros have this packaged already. If you need to compile it by hand, go for the latest SVN revision. The latest release cannot be compiled on anything but historic platforms and contains bugs that prevent it from debugging the ATmega328P anyway.
In order to use On-Chip Debugging, the
DWEN bit in the high fuse needs to be enabled (set to zero). The exact fuse settings for debugging and the default fuse setting are these:
|Fuse||Default Setting||Debug Setting|
You can enable debugWIRE debugging by running (replace
<PROGRAMMER> by the name of your programmer, e.g.
dragon_isp in case of the AVR Dragon):
avrdude -p m328p -c <PROGRAMMER> -U hfuse:w:0x9a:m
And disable debugging via:
avrdude -p m328p -c <PROGRAMMER> -U hfuse:w:0xda:m
With the AVR Dragon, debugging is as simple as running:
make BOARD=arduino-nano debug
The memory map of the ELF file does not take the bootloader into account. The author of this text used an ISP to program the Arduino Nano during debugging to avoid any issues. You might want to do the same, e.g. via:
make BOARD=arduino-nano PROGRAMMER=dragon_isp flash
AVR_DEBUGDEVICEenvironment variable to the required flag to pass to AVaRICE, e.g. when using the Atmel-ICE you have to export
AVR_DEBUGDEVICE=--edbg. If the debug device is not connected via USB, you also need to export
AVR_DEBUGINTERFACEto the correct value.
Don't expect having a working network stack due to very limited resources.
|Board specific definitions for the Arduino Uno board. |