In 2018, Microchip released a new range of ATtiny microcontroller chips, called the "ATtiny 1-series" - presumably named from the naming pattern of the part numbers. In usual Atmel (now bought by Microchip) style, the first digit(s) of the part number give the size of the flash memory; the remaining give an indication of the size and featureset of the chip.
| ATtinyX12 | 8 pin package, 5/6 IO pins | ATtiny212, ATtiny412 |
| ATtinyX14 | 14 pin package, 11/12 IO pins | ATtiny214, ATtiny414, ATtiny814, ATtiny1614 |
| ATtinyX16 | 20 pin package, 17/18 IO pins | ATtiny416, ATtiny816, ATtiny1616, ATtiny3216 |
| ATtinyX17 | 24 pin package, 21/22 IO pins | ATtiny417, ATtiny817, ATtiny1617, ATtiny3217 |
I'll write more about these new chips in another post - there's much change from the older style of ATtiny chips you may be familiar with. Many new things added, things improved, as well as a couple of - in my opinion - backward steps.
This post is largely a reminder to myself, and a help to anyone else, on how to build code for these new chips. The trouble is that they're newer than the avr-libc support package in Debian, meaning that you can't actually build code for these yet. Such an attempt will fail:
$ avr-gcc -std=gnu99 -Wall -Os -DF_CPU=20000000 -mmcu=attiny814 -flto -ffunction-sections -fshort-enums -o .build/firmware.elf src/main.c
/usr/lib/avr/include/avr/io.h:625:6: warning: #warning "device type not defined" [-Wcpp]
# warning "device type not defined"
^
In file included from src/main.c:4:0:
src/main.c: In function ‘RTC_PIT_vect’:
src/main.c:33:5: warning: ‘RTC_PIT_vect’ appears to be a misspelled signal handler, missing __vector prefix [-Wmisspelled-isr]
ISR(RTC_PIT_vect)
^
src/main.c:35:3: error: ‘RTC’ undeclared (first use in this function)
RTC.PITINTFLAGS = RTC_PI_bm;
^
...
This is caused by the fact that, while avr-gcc has support for the chips, the various support files that should be provided by avr-libc are missing. I've reported a Debian bug about this. Until it's fixed, however, it's easy enough to work around by providing the missing files.
Start off by downloading the "Atmel ATtiny Series Device Support" file from http://packs.download.atmel.com/. This is a free and open download, licensed under Apache v2. This file carries the extension atpack but it's actually just a ZIP file:
$ file Atmel.ATtiny_DFP.1.3.229.atpack Atmel.ATtiny_DFP.1.3.229.atpack: Zip archive data, at least v1.0 to extract
Note that by default it'll unpack into the working directory, so you'll want to create a temporary folder to work in:
$ mkdir pack $ cd pack/ $ unzip ~/Atmel.ATtiny_DFP.1.3.229.atpack Archive: /home/leo/Atmel.ATtiny_DFP.1.3.229.atpack creating: atdf/ creating: avrasm/ creating: avrasm/inc/ ...
From here, you can now copy the relevant files out to where avr-gcc will find them:
$ sudo cp include/avr/iotn?*1[2467].h /usr/lib/avr/include/avr/
$ sudo cp gcc/dev/attiny?*1[2467]/avrxmega3/*.{o,a} /usr/lib/avr/lib/avrxmega3/
$ sudo cp gcc/dev/attiny?*1[2467]/avrxmega3/short-calls/*.{o,a} /usr/lib/avr/lib/avrxmega3/short-calls/
Finally, there's one last task that needs doing. Locate the main avr/io.h file (it should live in /usr/lib/avr/include) and add the following lines somewhere within the main block of similar lines. These are needed to redirect from the toplevel #include <avr/io.h> towards the device-specific file.
#elif defined (__AVR_ATtiny212__) # include <avr/iotn212.h> #elif defined (__AVR_ATtiny412__) # include <avr/iotn412.h> #elif defined (__AVR_ATtiny214__) # include <avr/iotn214.h> #elif defined (__AVR_ATtiny414__) # include <avr/iotn414.h> #elif defined (__AVR_ATtiny814__) # include <avr/iotn814.h> #elif defined (__AVR_ATtiny1614__) # include <avr/iotn1614.h> #elif defined (__AVR_ATtiny3214__) # include <avr/iotn3214.h> #elif defined (__AVR_ATtiny416__) # include <avr/iotn416.h> #elif defined (__AVR_ATtiny816__) # include <avr/iotn816.h> #elif defined (__AVR_ATtiny1616__) # include <avr/iotn1616.h> #elif defined (__AVR_ATtiny3216__) # include <avr/iotn3216.h> #elif defined (__AVR_ATtiny417__) # include <avr/iotn417.h> #elif defined (__AVR_ATtiny817__) # include <avr/iotn817.h> #elif defined (__AVR_ATtiny1617__) # include <avr/iotn1617.h> #elif defined (__AVR_ATtiny3217__) # include <avr/iotn3217.h>
Having done this we find we can now compile firmware for these new chips:
avr-gcc -std=gnu99 -Wall -Os -DF_CPU=20000000 -mmcu=attiny814 -flto -ffunction-sections -fshort-enums -o .build/firmware.elf src/main.c avr-size .build/firmware.elf text data bss dec hex filename 3727 30 105 3862 f16 .build/firmware.elf avr-objcopy -j .text -j .rodata -j .data -O ihex .build/firmware.elf firmware-flash.hex
Next post I'll write more about my opinions on these chips, highlighting some of the newer features and changes.
