3 questions
Forums:
Firstly thanks for all the help you guys have given. I've a couple of questions I hope you can answer
1 Can a piborg reverse be located remotely from the raspberry pi? If so what is the max distance and what limits this distance
2 With your diddyborg what amperage where the motors drawing ? And where and what size fuses should I use to protect the piborg reverse and battery
3 Would it be possible to put a keyword search on the forum I'm sure a lot of my questions have been covered I just don't know where to look.
Thanks again
piborg
Wed, 09/20/2017 - 09:19
Permalink
I2C length and fuses
The limiting factor is the I2C signals, these get weaker as the distance gets longer. This distance depends on a lot of things such as the voltage (3.3 V in our case), the speed (100 KHz for the Pi), and the cabling used. For longer distances the provided 3-pin cables are not really good enough, you need something which is better shielded from outside noise and has a lower capacitance per meter.
The best thing to do is to get some good cable (twisted pair ideally, such as Cat 5) and try the distance you want to see if it is okay. There is a good explanation of why I2C struggles with long cabling here, along with a possible solution to extend the length :)
The motor drive chips are good for a steady 5 A or brief 6 A bursts. If the fuse is placed between the battery and the PicoBorg Reverse you need enough current for both motor chips so I would say 12 A would be about right. If you also have a BattBorg or similar after the fuse I would increase it to 15 A.
I have re-enabled it for now on (Search on the tabs at the top) but bear in mind it only searches for whole words and not parts of words or phrases.