UPDATED: Where I describe how to use FlashForth, a phenomenal version of Forth for the ATmega328P to learn how to use Forth in an embedded system.
Notes for Video
This video demonstrates the ease of loading FlashForth on to an Arduino Uno, and replacing it with Optiboot, when you wish to use the Arduino software framework, again.
Copy the required .hex files to your desktop, see Sources, below for links.
ATmega328P Datasheet - strongly recommended to download the datasheet, you will need it!
A More Powerful Forth
I really like FlashForth. It is extremely well documented thanks to the developer, a few college papers, a board manufacturer and a great site. All of those sites have been incredibly helpful and I strongly recommend you spend time on those sites to better understand FlashForth. I have yet to find a bug and it is amazingly fast on an 8-bit processor such as the ATmega328.
FlashForth and the ATmega328P are perfect for the beginner to explore writing firmware for embedded processors. As the tutorials show, its extremely simple to build a system using either the PIC microcontrollers or the ATmega328P. I’d recommend the latter as the tools and information are widely available due to the ubiquity of the Arduino. The speed, age and 8-bit size of the 328P are an advantage, not a problem. Forth depends on understanding the microcontroller extremely well, as this is its strength. And the ATmega family might be one of the most well-documented microcontroller product lines ever.
What’s Required:
Arduino UNO or compatible board (target system) - this can be any version of the Arduino UNO and it doesn’t have to have the 28 pin integrated circuit (IC chip), it can have the surface mount version. Or the Arduino Nano, any Arduino-compatible ATmega328P microcontroller board will work. Microchip also has a ATmega328PB Xplained Mini for about $13 which is phenomenal. It has both a 328PB chip and an ATmega32U4 for serial communications and a hardware debugger (mEDBG). I have written about it here.$13-$25
AVR-compatible ICSP programmer (used to load code on to 328P chip). For example, another UNO, or the Microchip MPLAB Snap. I was using the AVR Dragon as I have had it for years, however, the board is “no longer available”. I just started using the Snap, and it works quite well with avrdude or the Microchip IPE software. Or if you have the ATmega328PB Xplained Mini, it can program itself! $0(ATmega328PB Xplained Mini)-$34(Microchip Snap)
This process will assume the command line using either Linux or Mac. Using Windows with Atmel Studio will be dramatically different. If you are using Windows, I’d encourage to visit Arduino-Forth, as he covers FlashForth incredibly well and is Windows-based. Instead of using avrdude on Windows, use the MPLAB IPE, it works well.
Using Microchip Snap
# Assume you have cloned or downloaded FlashForth from GitHub# do everything from the hex folder cd flashforth/avr/hex
ls
2560-16MHz-38400.hex 328-16MHz-38400.hex 32u4-16MHz-UART38400.hex 32u4-16MHz-USB.hex
# Connect the programmer (Microchip Snap) to the UNO using an ISP cable (See link below)# A good initial command is to confirm your programmer can "see" the UNOavrdude -p m328p -P usb -c snap_isp -t
# interactive mode, enter the command part to confirm ISP sees a 328P# then quit to exitavrdude> part
avrdude> quit
# command to write codeavrdude -p m328p -c snap_isp -e -U flash:w:328-16MHz-38400.hex:i -U efuse:w:0xff:m -U hfuse:w:0xda:m -U lfuse:w:0xff:m
# connect with a serial program like screen, serial, moserial etc
Using Microchip ATmega328PB Xplained Mini
cd flashforth/avr/hex
avrdude -p m328pb -P usb -c xplainedmini -t
part
quit
avrdude -p atmega328pb -c xplainedmini -P usb -U ./328-16MHz-38400.hex
Using Microchip IPE and Snap
Download the Microchip IDE. The IPE (Integrated Programming Environment) works quite well for programming boards on Windows/macOS/Linux. It appears you can only install the IPE via the IDE installation. It’s a pain. I selected only IPE and 8-bit processors and still ended up with over 2GB of bloat. I spent a little bit of time removing packs I didn’t use and was able to get it down to 1.46GB. Small victory. In the meantime, install the IDE…and only use the IPE for programming. I have instructions here for using the IDE to compile a new version of Flashforth.
With the IPE, you select your device, tool and add the hex file in the hex file: location. Click program and the IPE/Snap or IPE/Xplained Mini will take care of the rest.
2. Connect to Uno with a Serial program
Use a serial program such as CoolTerm and connect your Uno with FlashForth to your computer. The connection for FlashForth:
38400 baud, 8 bits/No parity/1 stop bit
XON/XOFF is off
Send “<CR>” for Enter. If it is sending “<CR><LF>”, then some words won’t work properly in Forth.
If all goes well, you’ll end up with a line which looks like this and enter a simple test to show that Forth is working:
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