New for this version was radio modules that had 2 radios per module. The reason I did that was it was easier to build the little larger module, using the designs I had tried before, and expansion was always in the consideration. This way I could simply leave off all the remote base(s) and just have one module installed which did the repeater control and the link radio for over the air control as well. If I wished to add a remote base, then just add a module. Here is the expanded radio module
In the earlier design I had the modules plug into the main board, I dropped that idea due to space considerations. The board, and the modules were simply getting too tall for a 2RU enclosure, which was the biggest I wanted to use for this first prototype.
I also stuck with the use of robotic headers. The reason I liked these was one, they were easy to obtain in bulk, I can remove and replace wires at will, and the were easy to cut. If I needed only 7 wires in a connector, I could use two 4 pin connectors and simply cut off one of the wire positions on one, sand it a little and it looked good. I bought these at Pololu in Las Vegas. They were fast shippers and had a wide variety to choose from, but there are lots of vendors out there for these headers, and I have no stake in Pololu, they were just the best for me.
So version 10 main board......
Version 10 incorporated for the first time both the computer port and the MCU port. I had started using the Arduino 328 ( UNO R3) in version 5 but switched to the Arduino Mega for version 10. I simply needed more input and outputs and the Mega fit the bill. As you can see in the design this version not only included the ability of the MCU to take over for the computer in the event of a computer failure, and keep the repeater going, but it also keyed all of the radios when asked to. This design also was the first time I decided to use a IPS ( or intermediate power supply). I dont like feeding the arduino 12VDC, as the SMD voltage regulator, can handle the step down in voltage, but I found it ran hotter than I like. I really dont want to be changing out voltage regulators. Im also looking longevity. I took the 12Vdc, fed an 8V LDO VR and then fed that to the 5V LDO VR. This gave me 5V for logic gates, and I fed the Arduino the 8V for its operation. Since it has a on board voltage regulator, 8V knocked down to 5V allowed the voltage regulator on the Mega to run all day and never get hot...problem solved
Version 10 also has the MCU and the node computer running basically in tandem. If the computer fails for whatever reason, the MCU could care less since its already switching signals as the computer does. I used diodes to isolate the computer and the MCU signals from back feeding each other. Also I sent out 5V and a additional ground to the actual radios. I did this in case in the the future a relay was needed, or monitoring circuits needs voltage, then the 5V regulated power was already there and could be used.
The board design were sent off and came back looking nice. Here is the final layout of the design board for the main board
With the modules not piggybacked on the main board the use of the additional ports was needed. This is where the headers really aided in the mock up of the design. Here I was working on the firmware and just needed to check out the time it took to loop through the sketch. But, it works and the headers make it fast and easy to throw something together and test
I had also started looking at what I was going to do as far as the face plate and the indicator lights and statuses was concerned. Here I have the LEDs mocked up for the COR and PTT lines from each radio. With all of the initial testing done it was finally time to think about what the MCU was going to do, so time to look at the arduino sketches and the microcontroller
No comments:
Post a Comment