Shipping to United States starts at $8.00
Caught in a spin loop with no end in sight.
This ATmega328p based programmable board has headers for a mezzanine shield (RPUpi or RPUadpt). User's firmware application can monitor the input current with a high side current sense (ZXCT1087) with ADC channel six, and the input voltage with a voltage divider on channel seven. Six digital lines are connected through level shifters to 3.5mm plated through holes (for pluggable headers that face perpendicular to the optional DIN rail mounting). The Input Capture (ICP1) pin is setup for interfacing pulse sensors (Hall/VR or other) and provides a 100 Ohm termination that is suitable for a CAT5 pair. Input Capture is the best way to measure pulse edge timing, such as from a flow meter. Two Analog channels are available each with 22mA current sources from the VIN power, which should work with 4-20 mA sensors. The six digital connections have two groups that each have a 22mA source. Each digital line can sink the entire current source (e.g. the current source is intrinsically reliable when used with a digital input) or it can be divided between them with a resistor. The digital lines are clamped to an ESD node that discharges into VIN so the inputs level shifter should not be damaged from the spark from a finger (assuming human body sized capacitance).
I'm working on something like a garden SCADA system, this board started as a way to test the circuits and check some of the design ideas with a well-known (though somewhat limited) micro-controller. It is essentially an Arduino Uno with level shifting, current sources, and SMPS added and the USB stuff removed.
It uses the open source AVR toolchain found on Debian that has spread to most of the other Operating Systems. With the toolchain installed, the AVR application can compile locally (e.g. on a Raspberry Pi, Mac, or Windows 10). The hardware provider is not supplying the development tools, so if they are broken then fixing them ends up being a community effort. The good news on the consumer side is that the supplier can go belly up without affecting the availability of the development tools.
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United States Postal Service: Priority Mail
Priority Mail Small Flat Rate Box will hold two RPUno, or two shields (RPUftdi or RPUadpt) and an RPUno.
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I am working on what may be thought of as a garden SCADA system, it is based on securely connecting a host computer through RS-422 to multiple microcontrollers. I have strayed from RS-485 in favor of retaining existing software (e.g. avrdude, picocom, PySerial...) and have an interface that can act like an interactive terminal session.