This is just support for the chip, no boards are currently supported.
However, you can use this target on a custom board.
Notes:
- This required a new runtime and machine implementation, because the
hardware is actually very different (and much nicer than older
AVRs!).
- I had to update gen-device-avr to support this chip. This also
affects the generated output of other AVRs, but I checked all chips
we support and there shouldn't be any backwards incompatible
changes.
- I did not implement peripherals like UART, I2C, SPI, etc because I
don't need them. That is left to do in the future.
You can flash these chips with only a UART and a 1kOhm resistor, which
is really nice (no special hardware needed). Here is the program I've
used for this purpose: https://pypi.org/project/pymcuprog/
This refactors gen-device-avr to output two different formats: one for
all the existing AVR chips (that don't really have the concept of a
peripheral, just a bunch of registers), and one for all the new chips
like the ATtiny1616 (tinyAVR 1-series and 2-series) that have
peripherals like the Cortex-M chips with type structs and instances.
I checked the generated code for all the AVR chips we have support for
(atmega1280, atmega1284p, atmega2560, atmega328p, atmega32u4, attiny85)
and while the generated Go code did change, it looks safe to me.
This tool can be very useful to compare binary sizes as output by
`-size=short`.
This is a tool I wrote a while ago. It's not perfect (we should probably
use a geomean) but it works well enough to get a good idea on the binary
size impact of a change.
- Use compiler-rt and picolibc instead of avr-libc.
- Use ld.lld instead of avr-ld (or avr-gcc).
This makes it much easier to get started with TinyGo on AVR because
installing these extra tools (gcc-avr, avr-libc) can be a hassle.
It also opens the door for future improvements such as ThinLTO.
There is a code size increase but I think it's worth it in the long run.
The code size increase can hopefully be reduced with improvements to the
LLVM AVR backend and to compiler-rt.
- rename Bitfield to Constant
- add methods to the exiting types to set/get bitfields
- integrate clustered registers
- add cluster size to properly add filler at the end of the structure
- fix structures with leading filler (i.e. for FICR_Type.INFO in nfr9160)
- shorten the function name when prefix and suffix are identical. i.e. GetSTATE_STATE vs GetSTATE
This change implements __sync atomic polyfill libcalls by disabling interrupts.
This was previously done in a limited capacity on some targets, but this change uses a go:generate to emit all of the calls on all microcontroller targets.
Instead of doing everything in the interrupt lowering pass, generate
some more code in gen-device to declare interrupt handler functions and
do some work in the compiler so that interrupt lowering becomes a lot
simpler.
This has several benefits:
- Overall code is smaller, in particular the interrupt lowering pass.
- The code should be a bit less "magical" and instead a bit easier to
read. In particular, instead of having a magic
runtime.callInterruptHandler (that is fully written by the interrupt
lowering pass), the runtime calls a generated function like
device/sifive.InterruptHandler where this switch already exists in
code.
- Debug information is improved. This can be helpful during actual
debugging but is also useful for other uses of DWARF debug
information.
For an example on debug information improvement, this is what a
backtrace might look like before this commit:
Breakpoint 1, 0x00000b46 in UART0_IRQHandler ()
(gdb) bt
#0 0x00000b46 in UART0_IRQHandler ()
#1 <signal handler called>
[..etc]
Notice that the debugger doesn't see the source code location where it
has stopped.
After this commit, breaking at the same line might look like this:
Breakpoint 1, (*machine.UART).handleInterrupt (arg1=..., uart=<optimized out>) at /home/ayke/src/github.com/tinygo-org/tinygo/src/machine/machine_nrf.go:200
200 uart.Receive(byte(nrf.UART0.RXD.Get()))
(gdb) bt
#0 (*machine.UART).handleInterrupt (arg1=..., uart=<optimized out>) at /home/ayke/src/github.com/tinygo-org/tinygo/src/machine/machine_nrf.go:200
#1 UART0_IRQHandler () at /home/ayke/src/github.com/tinygo-org/tinygo/src/device/nrf/nrf51.go:176
#2 <signal handler called>
[..etc]
By now, the debugger sees an actual source location for UART0_IRQHandler
(in the generated file) and an inlined function.
This change adds support for the ESP32-C3, a new chip from Espressif. It
is a RISC-V core so porting was comparatively easy.
Most peripherals are shared with the (original) ESP32 chip, but with
subtle differences. Also, the SVD file I've used gives some
peripherals/registers a different name which makes sharing code harder.
Eventually, when an official SVD file for the ESP32 is released, I
expect that a lot of code can be shared between the two chips.
More information: https://www.espressif.com/en/products/socs/esp32-c3
TODO:
- stack scheduler
- interrupts
- most peripherals (SPI, I2C, PWM, etc)
- Add some extra fields: FPUPresent, CPU and NVICPrioBits which may
come in handy at a later time (and are easy to add).
- Rename DEVICE to Device, to match Go style.
This is in preparation to the next commit, which requires the FPUPresent
flag.
This doesn't change the firmware, but it does make the disassembly of
the ELF files. Before:
Disassembly of section .text:
00000000 <(machine.UART).Write-0x100>:
0: 20001000 .word 0x20001000
4: 000009db .word 0x000009db
8: 00000f05 .word 0x00000f05
c: 00000f0b .word 0x00000f0b
10: 00000f05 .word 0x00000f05
After:
Disassembly of section .text:
00000000 <__isr_vector>:
0: 20001000 .word 0x20001000
4: 000009db .word 0x000009db
8: 00000f05 .word 0x00000f05
c: 00000f0b .word 0x00000f0b
10: 00000f05 .word 0x00000f05
The difference is that the disassembler will now use a proper symbol name
instead of using the closest by symbol (in this case, (machine.UART).Write).
This makes the disassembly easier to read.
Move element description formatting to a function
Export struct fields for use in the template
Add template helper functions
Multiline comments for interrupts and peripherals
Export more fields
Move comments to the top of each element
Do not remove line breaks from descriptions
The template code should gracefully handle line breaks now
go fmt gen-device-svd.go
This commit changes the number of wait states for the stm32f103 chip to
2 instead of 4. This gets it back in line with the datasheet, but it
also has the side effect of breaking I2C. Therefore, another (seemingly
unrelated) change is needed: the i2cTimeout constant must be increased
to a higher value to adjust to the lower flash wait states - presumably
because the lower number of wait states allows the chip to run code
faster.
This is only very minimal support. More support (such as tinygo flash,
or peripheral access) should be added in later commits, to keep this one
focused.
Importantly, this commit changes the LLVM repo from llvm/llvm-project to
tinygo-org/llvm-project. This provides a little bit of versioning in
case something changes in the Espressif fork. If we want to upgrade to
LLVM 11 it's easy to switch back to llvm/llvm-project until Espressif
has updated their fork.
For now, this is just an extra flag that can be used to print stack
frame information, but this is intended to provide a way to determine
stack sizes for goroutines at compile time in many cases.
Stack sizes are often somewhere around 350 bytes so are in fact not all
that big usually. Once this can be determined at compile time in many
cases, it is possible to use this information when available and as a
result increase the fallback stack size if the size cannot be determined
at compile time. This should reduce stack overflows while at the same
time reducing RAM consumption in many cases.
Interesting output for testdata/channel.go:
function stack usage (in bytes)
Reset_Handler 332
.Lcommand-line-arguments.fastreceiver 220
.Lcommand-line-arguments.fastsender 192
.Lcommand-line-arguments.iterator 192
.Lcommand-line-arguments.main$1 184
.Lcommand-line-arguments.main$2 200
.Lcommand-line-arguments.main$3 200
.Lcommand-line-arguments.main$4 328
.Lcommand-line-arguments.receive 176
.Lcommand-line-arguments.selectDeadlock 72
.Lcommand-line-arguments.selectNoOp 72
.Lcommand-line-arguments.send 184
.Lcommand-line-arguments.sendComplex 192
.Lcommand-line-arguments.sender 192
.Lruntime.run$1 548
This shows that the stack size (if these numbers are correct) can in
fact be determined automatically in many cases, especially for small
goroutines. One of the great things about Go is lightweight goroutines,
and reducing stack sizes is very important to make goroutines
lightweight on microcontrollers.
Previously, the RAM was set to start at address 0. This is incorrect: on
AVR, the first few addresses are taken up by memory-mapped I/O. The
reason this didn't lead to problems (yet) was because the stack was
usually big enough to avoid real problems.
This commit adds support for software vectoring in the PLIC interrupt.
The interrupt table is created by the compiler, which leads to very
compact code while retaining the flexibility that the interrupt API
provides.
This commit lets the compiler know about interrupts and allows
optimizations to be performed based on that: interrupts are eliminated
when they appear to be unused in a program. This is done with a new
pseudo-call (runtime/interrupt.New) that is treated specially by the
compiler.
This simplifies the code. The fields are blank anyway so there is no way
to access them anyway (volatile or not).
Also do some other related simplifications of the code that result from
this change.
This should make it more maintainable. Another big advantage that
generation time (including gofmt) is now 3 times faster. No real attempt
at refactoring has been made, that will need to be done at a later time.
This brings a big speedup. Not counting gofmt time,
`make gen-device-avr` became about 3x faster. In the future, it might be
an idea to generate the AST in-memory and write it out already
formatted.
