DFRduino Mega 2560 program IO OP

We are looking for an electronic engineer to program the DFRduino Mega 2560 (or equivalent) and design voltage regulation. The microprocessor must have at least 16 (or more) inputs (I/P) and at least 24 outputs (O/P) preferably more. The I/P is received via a closed contact (momentary switch) to the micro processor. The protocol, which we will provide as a document, will then communicate via RS485 to our controller. Our controller is a software map which does a range of activities but namely maps Inputs to corresponding outputs. Hence a I/P is activated and a correspond O/P is enabled. The O/P's consist of LED lights. And the I/P is held active and the O/P remains active until an I/P reset is sent and the O/P is cancelled. The protocol document describes and provides examples for the simple "Poll and Response" packets via a RS485 communication line to our controller and will be supplied as part of this job. Each Micro Processor must have an address - from address 00 to address 31. Up to 32 micro processors (DFRduino Mega 2560) can be connect to one of our controllers. Thus 32 micro controllers would enable 512 inputs (16*32) and 768 (24*32) outputs. The design requires that the IP's and OP's would come via a punch down frame. The programer/contractor would provide a basic drawing showing the IP and OP connectivity and setup from the microprocessor board. The Microcontroller (MCU) will provide all logic functions, scan the I/P’s and control the LED outputs and is responsible for all timing dependant operations including serial communications. The I/P Interface contains all the circuit necessary to convert the low power & low voltage signals from the MCU to the levels required by the I/P’s, it also provides first level switch de-bounce filtering and protection of the MCU from low voltage interference. Inputs will be designed to accept input voltages in the range of 0 to 24VDC. A Voltage regulator is required to convert the nominal 24Vdc power input to 5Vdc as required by the MCU and RS-485 circuits, this regulator will be designed to accept an input voltage range down to 7Vdc to allow the MCU to operate in the presence of voltage dips and minor interruptions. In order to monitor the integrity of the power in terms of excessive voltage drops due to poor wiring or excessive load the power supply input voltage will be compared to a threshold level and the result reported to the CCM. Current limiting of the 24V input will be current limited by a self resetting fuse or a slow blow fuse rated at the expected maximum current draw for the entire module if all outputs are active. Connection of the power to the module must be with cable rated at 3 or more times the rating of the fuse. The LED drivers take the 5V signal from the MCU and provide a current sink output capable of driving incandescent light globes or other types of lamp with a current up to 500mA at 22Vdc or 10watts. Each output will be current limited by a self resetting fuse. This device is designed to be wired within a single building. Connection to the host controller will be via serial communications on a multi-drop RS-485 differential bus, the transceiver will provide a non isolated (hardwired) communications link. Transient suppression components will provide protection from transients normally encountered in residential or commercial buildings when some types of electrical equipment are switched on or off. IP Hardware The IO Module functionality is dependant on the type of call point connected, all I/P’s are required to exhibit latching. The IP interface in the IO Module will accept 24V inputs from momentary or latching type switches, where the call point uses momentary switches the latching is performed in software. An open collector output when activated by the MCU will effectively connect the reassurance- line to 0Vdc causing the reassurance lamp to light up. The reassurance light can be either a lamp ( max 2W @ 24Vdc ) or a power LED with a series resistor.