October 17, 2013 in 8 Channel PDU by Joshua Oster-Morris
I received the new prototype PCBs on Tuesday and built one up last night. I have not yet had a chance to play with it, but I intend to very soon. I modified the BOM for the power board and when I put in my part order last week I forgot a part that this new MCU board will require so I am currently in a holding pattern for a couple days.
With regards to the new board, there are always so many things that can go wrong with a new board design so we won’t know much until I’ve had a chance to test it. This board has some really cool features on it that make it the first version I would feel comfortable installing in a vehicle other than my own. Previous versions did not have all the safety features this version has. It is also VERY energy efficient in stand by mode.
The next step is to confirm the new features on this board function as expected. Assuming they do, I will decide if I will be dumping the digital inputs completely and using the analog inputs as digital inputs. The way I’ve designed the circuit I believe it will work well. Until I test it I will not be making efficacy claims though. The last step then is to decide if I want to continue with the “pig tail” wiring harness or change to something with no wires included. I am inclined to dispose of the wires as it makes the device much easier to ship but I will have to examine the costs and final form factor and make a decision once I have fewer variables.
October 2, 2013 in 8 Channel PDU by Joshua Oster-Morris
I am currently testing the analog to digital converter (ADC) I selected to use for the new analog inputs on the PDU. In the photo below I’ve got it wired up and plugged into one of my custom made project boards I use to test out ideas for the PDU. So far, so good. The ADC and custom input buffer circuitry are working well and are accurate to within 40mV from 0-21V. That is more than adequate for my purposes so it is fair to say that I am pleased thus far. It takes longer to get a value from the ADC than it does from the digital inputs but it doesn’t take too long (≈ 400uS) so if I had 8 analog inputs to read it would take less than 4mS (1/250th of a second) total which I expect is fast enough that user will not notice a delay. I am feeling like it make be possible to remove the digital inputs circuitry and replace them with dual purpose Analog and Digital Inputs for the final product. The new prototype PDU boards (with all the latest tweaks including the analog inputs) are being fabricated as we speak and they should be here in a couple weeks at most. I’m very excited to get them because one of them has a date with a project motorcycle I am building up in Arizona and it needs a fuse block badly.
As you can see, testing electronics is an untidy business. Believe it or not, I actually know whats going on here.