Cable questions

[JavaLaurence]

Got a couple of questions re: cables.

 

Is TF planning to offer a female-female connector so that two cables can be hooked together to obtain a longer cable?

 

Is TF planning to offer a cable-making kit? If not, can we be pointed in the right direction (links) so that users can make non-standard lengths? TF sells the connectors, but how does one attach these to a suitable cable?

 

Thx.

 

  Laurence

 

PS. Trying to install my LCD in kitchen with stack in cellar. Unfortunately, I need 3.5m to reach. :-S

[borg]

We don't recommend using longer Bricklet cables than 2m. You will very likely have problems controlling the LCD over that range (the voltage drop will be too big).

[photron]

For longer connections there is the RS485 Master Extension that allows to split stacks with up to 1200m cable in between. You'd need 1x Master Brick (as base for the second stack) and 2x RS485 Master Extensions (one for each stack) in addition to your current stack.

[JavaLaurence]

Thanks for the replies. I appreciate the modular nature of the product range, but adding a whole new stack (you forgot new power supply, there's no USB floating in our kitchen), just to bridge a few feet seems like lots of $$$ for very little.

 

I read that I2C wiring can carry signals over a much longer range, so can you tell me which aspect of your cable design is the most voltage-drop dependent? Would adding 2m of wiring between the connectors be a guaranteed waste of time, or do you think there's a chance it could work (just like my stack apparently having no problem with switching on/off my water pump - an inductive load :-)

 

Thx again.

 

  L.

[photron]

The 5V line is used to power the LCD. If the cable gets to long the LCD will get a too low voltage on the 5V line and might not work anymore.

 

Whether or not I2C over a longer cable will work for you depends on your environment. A long cable acts as an antenna capturing interference that can disturb the I2C communication.

 

The 2m Bricklet cables work in most cases. A longer cable might work for you, that depends on your specific setup and environment. So you'll have to try

[benatweb]

Hi,

 

I don't know if this will work with the Tinkerforge Bricklet-cables and the LCD-Bricklet, but there are Step-Up-Converters (similar to the Step-Down-Power-Supply, but instead of converting some voltage to a defined lower voltage, their output voltage is higher than their input voltage), e.g. this one. So if a longer cable does not work out, you might want to try putting one of them in beetween if the voltage drop turns out to be to high. (I'm not sure if it can output enough current for the LCD-Bricklet though.)

 

Or maybe you can add a 5V Power Supply in your kitchen to power the LCD from separately (connect the power cables on the LCD-side of the cable to the power supply instead of the stack), but you'll have to ask the Tinkerforge guys about that, not sure if this will cause problems.

[JavaLaurence]

Yes, even with my extremely limited electronics knowledge, I thought of powering the LCD separately too. I could sever the 5V and ground lines (pin 1 & 2) of the bricklet cable, and provide those lines from a little supply next to LCD. A hack in the purest sense of the word ;-)

 

But I'll try lengthening the cable first. Ya never know..