New 'labman' tool

Simon Glass sjg at
Sun Apr 19 23:08:20 CEST 2020

Hi Wolfgang,

On Sun, 19 Apr 2020 at 14:17, Wolfgang Denk <wd at> wrote:
> Dear Simon,
> In message <CAPnjgZ04mLcNzbJJYzK9g_W+j0KB9ge5mYjpyDmqhe7rgCcO4g at> you wrote:
> >
> > I have been fiddling with setting up a lab and have found it quite a
> > pain. Lots of USB connections and things sometimes break.
> ...
> > Hubs are a pain because their internal numbering does not always
> > correspond to their visible port numbers.
> >
> > Also when something goes wrong with a component in the lab, it is hard
> > to know which one is broken and which port it is on.
> This is a repeating story, and my strong recommendation is just to
> get rid of USB devices as much as possible.
> Where exactly do you need USB stuff?
> - TTL to serial converters - there is a wide range of (usually
>   MAX3232 based) TTL to RS232 converters; which you can then connect
>   to some standard terminal server (aka console server).
>   There is also TTL to WiFi adapters, though not exactly cheap, for
>   example [1]
>   A DIY approach could use some ESP8266 based system - you get a
>   Mini NodeMCU for as little as $0.10 today [2]; adapting the free
>   tasmota firmware to work as serial converter is easy.
> - Power switching - again, there is a large number of ESP8266 based
>   wifi plugs that can run Tasmota; I prefer the Tuya compatible
>   ones, because you can flash the Tasmota firmare OTA without any
>   physical manipulation [3], and they are relatively cheap ($8.95
>   per plug, for example [4]). If in doubt, use standard Sonoff
>   devices.
> - Relays (boot mode switches etc.) - for example the Sonoff 4CH Pro
>   R2 offers 4 relays, and again it can be flashed to run Tasmota,
>   [5].
>   Alternatively, just use a ESP8266 NodeMCU and a Transistor (and
>   maybe a relay).
> You get the pattern?  Most of these things can easily be replaced
> with devices that can be controlled over WiFi (using for example
> MQTT over TLS), using Free Software only.  You can access averything
> over the same mechanism, and you don't need to route so many cables
> aby more. USB maximum cable length?  Forget it.  USB hubs? Forget
> it.

I am using a DLI which is Ethernet-connected, but everything else is
USB so far. Thanks for all the info and pointers. I've ordered a few
of these things so will see how it goes.

For TTL serial I found [1].

I have not been super-excited about connecting things on wifi, but I
suppose I can put a unit near the lab and it does save one cable.

Some devices are USB-only, like the SDwire and Dediprog em100. Some
boards use USB and their boot ROM to download U-Boot (e.g. tegra,
sunxi, at91, imx, exynos). So there is always going to be a lot of USB
in my lab.

I have been looking for an IP-connected USB servo (e.g. 16 USB ports
and connected to the LAN), but cannot find anything much.

> SCNR - I'm aware that all this is pretty off topic here.

Yes but still a helpful reminder, thanks!

- Simon


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