[OpenTRV-dev] Help getting serial connection to Radbot

[Robert May]

Thanks all.  I'm there (or at least I think I am).

I changed a number of things - the voltage I'm driving the Radbot (now at
3.3v), I remade my solder connections and replaced the wires/connectors as
I think one of the dupont connectors was loose, and I moved to using the
built in serial port of the PI (/dev/AMA0).   I'll see if I can work out
which of these was actually the culprit.

Out of interest, what is the max voltage that is safe to run the Radbot.
If I understand this page correctly (
https://github.com/tyrken/heatmon/wiki/Reprogramming-Radbot-TRVs) then it
is suggesting powering it at 5V (direct from the USB port)

Onwards.
Rob.

On Sun, 14 Feb 2021 at 21:45, Damon Hart-Davis <dhd at exnet.com> wrote:

> Hi,
>
> 1) FWIW, when I am powering remotely, eg to reflash, I tend to run at 3.6V.
>
> 2) Yes, I think that we label our TX and RX the ‘wrong’ way round and have
> confused ourselves from time to time.  Almost certainly an early error or
> at least bad choice by me, reinforced by my trying to then be consistent
> across schematics.
>
> 3) FWIW I use a FTDI TTL-232R-3V3 to talk to Radbots.
>
> Rgds
>
> Damon
>
> On 14 Feb 2021, at 20:52, Robert May <rob at themayfamily.me.uk> wrote:
>
> Thanks Damon, Christoph.
>
> I already moved to soldering my connections to eliminate that issue.
>
> I can see the TX LED flash on my dongle when I hit <return>, and if I swap
> the tx/rx connections so I have tx on dongle to tx on Radbot and rx on
> dongle to rx on Radbot then after I hit <return> I see the rx led on the
> dongle flash approx. every 2 seconds for a while - so I *think* I'm waking
> it up.    This feels wrong, but past experience tells me that there is
> sometimes confusion over how rx and tx pins are marked.
>
> But I see nothing in my terminal.  I've shortened the wires as much as I
> can, and I'm sure that my grounds are OK
>
> Can you expand on what you mean by "perhaps one of the devices doesn’t
> like the 3.0V supply"?
>
> Here's a couple of pictures
>
> https://www.dropbox.com/s/s8jdv6j9a4covw3/Photo%2014-02-2021%2C%2020%2041%2054.jpg?dl=0
>
> https://www.dropbox.com/s/sp819pw2ds1lf73/Photo%2014-02-2021%2C%2020%2042%2011.jpg?dl=0
> (not a good shot, but I'm sure the pins and +ve terminals are not touching)
>
> Any other ideas?  I've been staring at this all day and can't see what's
> wrong.
>
> Rob.
>
>
> On Sun, 14 Feb 2021 at 19:33, Christoph M. Wintersteiger <
> christoph at winterstiger.at> wrote:
>
>> Hi Rob,
>>
>>
>>
>> That’s great, you’ve got very far in a very short amount of time!
>>
>>
>>
>> It sounds like you’re “holding” the wires on – just solder them on if you
>> have a soldering iron around, it’s easy enough to take them back off after
>> the operation.
>>
>>
>>
>> I can imagine that there’s a ground potential problem and perhaps one of
>> the devices doesn’t like the 3.0V supply. The Radbot takes very little
>> power and I was able to simply power it from my USB-serial adapter, but
>> that depends on the adapter of course. Alternatively, the RPi also has a
>> 3.3V supply (and 5.0V too) and it has a serial port right next to the
>> supply pins too, so if you have a few breadboard wires around, that would
>> be a simple and quick alternative.
>>
>>
>>
>> Cheers,
>>
>> Christoph
>>
>>
>>
>> *From:* OpenTRV-dev <opentrv-dev-bounces at lists.opentrv.org.uk> *On
>> Behalf Of *Robert May
>> *Sent:* Sunday, 14 February, 2021 18:24
>> *To:* Closed list for developer discussions <
>> opentrv-dev at lists.opentrv.org.uk>
>> *Subject:* [OpenTRV-dev] Help getting serial connection to Radbot
>>
>>
>>
>> I've finally found time to unbox my Radbots.   The plan is to build a
>> combined stats hub and boiler controller based on a RPi.
>>
>>
>>
>> I've successfully compiled the code Christoph shared (
>> https://github.com/wintersteiger/wlmcd) and used to to show the one
>> Radbot I've powered up transmits and that I can receive the frames using a
>> CC1101/RPi combination.  Of course the decryption fails as I've yet to set
>> a decryption key.
>>
>>
>>
>> I'm struggling to get a connection over the serial port to the Radbot.
>> I'm trying to follow the instructions shared by Tristan (
>> https://github.com/tyrken/heatmon/wiki/Reprogramming-Radbot-TRVs) but I
>> can't seem to get any comms over the serial port.
>>
>>
>>
>> I've opened up my radbot to get better access to the pads.
>>
>> I'm powering the Radbot from a bench power supply at 3.0V
>>
>> I've got a USB serial dongle operating at 3.3V logic, grounded to the -ve
>> supply.
>>
>> I think I'm hold the rx/tx lines on the pads (tx from my dongle to rx on
>> the radbot and rx on the dongle to tx on the Radbot), but I get nothing
>> from 'screen' that I'm using for my terminal.
>>
>>
>>
>> As far as I know I'm using 4800baud, 8-N-1 (screen /dev/ttyUSB0 4800),
>> which I believ to be the expected settings?
>>
>>
>>
>> Can anyone see anything that I'm doing wrong or give me a pointer to
>> things that I can try. ?
>>
>>
>>
>> Thanks,
>>
>> Rob.
>>
>>
>>
>>
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