feat: add w5500 driver #788

nrwiersma · 2025-08-29T16:08:11Z

This adds a driver for the w5500 ethernet chip:
https://docs.wiznet.io/img/products/w5500/W5500_ds_v110e.pdf

While it uses interrupts, it does not use the interrupt pin as there is currently no way to implement a timed wait (something akin to a Futex). For this reason it is not as fast as it could be.

It also does not attempt to tackle DNS, just copping out and allowing the user to set a resolver when they configure the device.

I tried to abide by your Driver guide, let me know if anything is amiss.

w5500/w5500.go

ysoldak · 2025-11-10T09:26:55Z

w5500/io.go

+	waitTime := 500 * time.Microsecond
+	for {
+		if !deadline.IsZero() && time.Now().After(deadline) {
+			if debugging(debugDetail) {


Is this necessary? I'd suggest dropping all debug code, adds dependency from fmt -- and this is huge.

Removed. I am still using fmt for Errorf, but I can refactor this out if you need.

Yes, I'd prefer you remove all fmt usage from driver.

Look, I did this simple change in your example to trigger an error:

IP: netip.AddrFrom4([4]byte{192, 168, 1, 2}), SubnetMask: netip.AddrFrom4([4]byte{255, 255, 255, 0}), Gateway: netip.AddrFrom4([4]byte{192, 168, 1, 1}), + MaxSockets: 20, }) netdev.UseNetdev(eth)

And the result is this:

$ tinygo build -target=pico -size=full ./examples/w5500 code rodata data bss | flash ram | package ------------------------------- | --------------- | ------- 0 69 3 2 | 72 5 | (padding) 1571 0 9 22 | 1580 31 | (unknown) 240 0 0 0 | 240 0 | /Users/ysoldak/code/tinygo/targets 1862 0 0 0 | 1862 0 | C compiler-rt 0 168 0 0 | 168 0 | C interrupt vector 80 0 0 0 | 80 0 | C picolibc 0 0 0 4096 | 0 4096 | C stack 340 0 0 0 | 340 0 | Go interface assert 534 0 0 0 | 534 0 | Go interface method 0 2012 0 0 | 2012 0 | Go types 426 0 0 0 | 426 0 | cmp 0 0 44 0 | 44 44 | context 78 0 0 0 | 78 0 | device/arm 72 0 0 0 | 72 0 | device/rp 18 0 0 0 | 18 0 | errors 8998 221 28 0 | 9247 28 | fmt 24 0 0 0 | 24 0 | internal/binary 44 0 0 0 | 44 0 | internal/byteorder 754 21 0 0 | 775 0 | internal/fmtsort 140 2 0 0 | 142 0 | internal/itoa 5580 772 48 0 | 6400 48 | internal/reflectlite 560 86 0 0 | 646 0 | internal/task 2152 79 4 330 | 2235 334 | machine 488 0 0 7 | 488 7 | machine/usb/cdc 0 0 93 0 | 93 93 | machine/usb/descriptor 120 25 0 0 | 145 0 | main 294 0 0 0 | 294 0 | math/bits 6 32 0 8 | 38 8 | net 1174 52 0 8 | 1226 8 | net/netip 0 0 0 0 | 0 0 | os 24 0 0 0 | 24 0 | reflect 7266 788 9 771 | 8063 780 | runtime 980 0 0 0 | 980 0 | runtime/volatile 2942 0 0 0 | 2942 0 | slices 7884 15957 1338 0 | 25179 1338 | strconv 116 0 0 0 | 116 0 | sync 158 0 0 0 | 158 0 | sync/atomic 0 11 0 0 | 11 0 | tinygo.org/x/drivers/netdev 1092 86 0 0 | 1178 0 | tinygo.org/x/drivers/w5500 870 288 0 0 | 1158 0 | unicode/utf8 220 0 0 12 | 220 12 | unique ------------------------------- | --------------- | ------- 47107 20669 1576 5256 | 69352 6832 | total

Compare with compile result before change:

$ tinygo build -target=pico -size=full ./examples/w5500 code rodata data bss | flash ram | package ------------------------------- | --------------- | ------- 0 44 1 2 | 45 3 | (padding) 1295 0 11 22 | 1306 33 | (unknown) 240 0 0 0 | 240 0 | /Users/ysoldak/code/tinygo/targets 1484 0 0 0 | 1484 0 | C compiler-rt 0 168 0 0 | 168 0 | C interrupt vector 80 0 0 0 | 80 0 | C picolibc 0 0 0 4096 | 0 4096 | C stack 264 0 0 0 | 264 0 | Go interface assert 204 0 0 0 | 204 0 | Go interface method 0 1556 0 0 | 1556 0 | Go types 0 0 44 0 | 44 44 | context 78 0 0 0 | 78 0 | device/arm 74 0 0 0 | 74 0 | device/rp 24 0 0 0 | 24 0 | internal/binary 44 0 0 0 | 44 0 | internal/byteorder 140 2 0 0 | 142 0 | internal/itoa 4162 576 48 0 | 4786 48 | internal/reflectlite 560 86 0 0 | 646 0 | internal/task 2192 79 4 330 | 2275 334 | machine 488 0 0 7 | 488 7 | machine/usb/cdc 0 0 93 0 | 93 93 | machine/usb/descriptor 118 25 0 0 | 143 0 | main 8 0 0 0 | 8 0 | math/bits 6 32 0 8 | 38 8 | net 1154 36 0 8 | 1190 8 | net/netip 0 0 0 0 | 0 0 | os 7064 800 9 771 | 7873 780 | runtime 978 0 0 0 | 978 0 | runtime/volatile 1100 2062 1338 0 | 4500 1338 | strconv 158 0 0 0 | 158 0 | sync/atomic 0 11 0 0 | 11 0 | tinygo.org/x/drivers/netdev 1190 0 0 0 | 1190 0 | tinygo.org/x/drivers/w5500 396 288 0 0 | 684 0 | unicode/utf8 178 0 0 12 | 178 12 | unique ------------------------------- | --------------- | ------- 23679 5765 1548 5256 | 30992 6804 | total

compare flash sizes, check fmt and strconv sizes.

w5500/w5500.go

w5500/netdev.go

w5500/io.go

ysoldak · 2025-11-10T20:06:12Z

w5500/netdev.go

+			if err := d.listen(sockn); err != nil {
+				return errors.New("could not set socket to listen: " + err.Error())
+			}
+			break


Sorry, missed this one. Otherwise LGTM from me and ✅

Suggested change

break

ysoldak

LGTM, one tiny nit.

ysoldak · 2025-11-10T20:08:15Z

@deadprogram @soypat shall be fine to merge, what you think, guys?

soypat

Wow! Looks much better than the first time I looked at it. Good job with the guidance @ysoldak ! Lets get it merged!

soypat · 2025-11-10T22:49:37Z

examples/w5500/main.go

+		IP:         netip.AddrFrom4([4]byte{192, 168, 1, 2}),
+		SubnetMask: netip.AddrFrom4([4]byte{255, 255, 255, 0}),
+		Gateway:    netip.AddrFrom4([4]byte{192, 168, 1, 1}),


Very nice! netip is the best!

ysoldak reviewed Sep 22, 2025

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