After making some progress, I recently started to make a custom motherboard for the cara.
Doing so, I used a MAX232 (not 232) for the connection of uart2 (console).
Unfortunately, there's only silence on the host side, whereas the singnal level is at 8+ V, so the MAX's chargepump seems to work.
This time I triple-checked all connections, no error to be found.

Did anyone also try to make a connection using a (cheap) MAX233 and could share his experience with me?

If in doubt, I consider just removing the 232 and abandon that kind of connection (because 3232 ic is way to pricey, alternatives not available in DIP...)

Didn't you just answer the question yourself in another thread? You said that the MAX232 only takes 5V for input.
You could use a Transistor circuit to shift the Carambolas Tx signal to 5V for the MAX232 and then use a Zener Diode to shift the MAXs Tx signal down to 3.3V.

However, if you need the MAX just to connect that UART to the PC you should consider using the FT232RL. It's a common USB to serial TTL bridge IC that supports both - 3.3V and 5V - TTL levels on its pins. If you're making your own motherboard it'll be easy to accomodate this IC in your design.

Well, the datasheet to the 232 I'm using [it's from TI] states a min. Voltage of 2V for HIGH level, so that shouldn't be a problem at all - other way around, it was confirmed that the cara's inputs are 5V tolerant.

So that shouldn't be a problem.

FYI: For the connection to the PC I'm using a cheap PL2303 based USB-serial adapter.
[It's a shame most modern computers don't feature a serial connector anymore - well, a lot still *have* a serial connection available (pin headers) but don't feature easily accessable connectors for them; you'd have to add them yourself (which I did several times, but for my developments I prefer using a netbook - in which there's absolutely no serial connectivity)]

I'll quad-check the capacitors (maybe).

Hello,

I don't know the production numbers you are planning, but for me 1.43 €+VAT for a single MAX2323 in DIP is not too pricey (1.13€ + VAT each at 10+). As an SMD device it's about 0.63€+VAT resp. 0.52€+VAT (seen at TME.eu).

Agreed, the TI 232 clone is much cheaper (0.26€+VAT each at 10+), but as long as we don't talk about 10.000+ units/year, I would guess that the difference is not worth the risk and hassle to use the 5V version.

Best regards,
Maveric00

You can use cheap 5V max232 clones with voltage divider 1K/3K

I'm developing an open source distributed domotic framework within my company, we are using Carambola for testing and implementing it but it can be ported to any platform.
Basically it give a set of REST API so any application can interface with it through the home network and we are planning to offer remote control to our customer.
It can interface itself with existing standards open or closed source, we've also built a thermostat with Carambola in it and controlled it through a smartphone (the beautiful Nokia N9) via wireless network.