digispark blink mips - openwrt

[Beto Sanchez]

Hi, tried to compile for a mips processor running OpenWRT TP-LINK TL-WDR3600

# GOOS=linux GOARCH=mips GOMIPS=softfloat go build -ldflags "-w" -a main.go

Report error

# gobot.io/x/gobot/platforms/digispark
../../gobot.io/x/gobot/platforms/digispark/digispark_adaptor.go:18:13: undefined: lw

This line is "littleWire lw"

// Adaptor is the Gobot Adaptor for the Digispark
type Adaptor struct {
        name       string
        littleWire lw
        servo      bool
        pwm        bool
        i2c        bool
        connect    func(*Adaptor) (err error)
}

[Ron Evans]

Hi, Beto

The Digispark is an ATTiny85 processor that Gobot can communicate with only when the correct firmware is installed on it.

Regarding MIPS support, at the moment that has not been implemented in Gobot. We would love to receive a PR that added it.

Hope that helps!

[Beto Sanchez]

Thanks Ron for your answer

I'm trying to do a cross compilation

--------------------------------------

export STAGING_DIR="/home/build/git/openwrt/staging_dir"
export TINY="/home/build/git/openwrt/build_dir/target-mips_24kc_musl/openwrt-sdk-ar71xx-tiny_gcc-8.3.0_musl.Linux-x86_64/build_dir/target-mips_24kc_musl/linux-ar71xx_tiny/linux-4.14.148"

export CC="/home/build/git/openwrt/staging_dir/toolchain-mips_24kc_gcc-8.3.0_musl/bin/mips-openwrt-linux-gcc"
export CGO_CFLAGS="--sysroot=$TINY -I$TINY/include -I$TINY/include/linux"
env CGO_ENABLED=1 GOOS=linux GOARCH=mips GOMIPS=softfloat go build -a main.go

-------------------------------------

and the compiler responds

# runtime/cgo
In file included from _cgo_export.c:4:
cgo-builtin-prolog:7:33: error: unknown type name 'ptrdiff_t'

I haven't found why report this error

[Ron Evans]

The Digispark Adaptor uses CGo, and CGo generally speaking does not work with cross-compilation. I think that is your problem.