There are many projects where Raspberry PI is used as the basis of the system, but there are a number of difficulties in providing power and interacting with external devices. I would like to share the experience of creating a small shield for the minicomputer, simplifying its application and increasing the reliability of the entire system.
A typical task solved with the help of Raspberry PI is a small home / industrial automation, in which there is a set of peripheral modules powered by 12-24 volts and having an RS-485 bus. In order to power Raspberry from the same power as the modules, you have to put a certain 5-volt converter and connect it via the GPIO or USB connector. To this is added another USB-RS485 or UART-RS485 adapter that sticks out of USB or somehow hangs on the GPIO connector. Such design options are not reliable.
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Talking with the Maxim-IC guy, I was missing a pull-up resistor on the RO. Fixed it! Thank you for your time and hope my solution will help someone! – Alexandre Lavoie Nov 4 '14 at 21:19
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