Alchitry Cu problems - Page 1
Forum section: electronics / general

author: prophoss
author_rank: Contributor
timestamp: January 17, 2022, 02:30:41 am
content: So I did this thing... I got a the Alchitry Cuhttps://alchitry.com/boards/cuthinking that it would be a good dev board that I could learn on with better documentation than my cheap Chinese dev board. It can be used with open source tool chain as well. The problem is that the I/O pins are no exactly what I had expected. It seems that the only way to add peripherals is to buy their IO board. So that is another $30 or so. Does anybody have any ides how to use the headers as they are? Is there a simpler option?

author: asmi
author_rank: Super Contributor
timestamp: January 17, 2022, 02:59:24 am
content: They provide a schematic for the board, so open it up to see what's what.

author: prophoss
author_rank: Contributor
timestamp: January 17, 2022, 03:11:54 pm
content: I looked at the pinout so I know what attaches to where. What I’m wondering is how do I attach a sensor to a pin? The bank has a different design I’ve not seen before.

author: asmi
author_rank: Super Contributor
timestamp: January 17, 2022, 03:43:29 pm
content: Quote from: prophoss on January 17, 2022, 03:11:54 pmNot sure I understand the question. What do you mean "bank has a different design"?

author: prophoss
author_rank: Contributor
timestamp: January 17, 2022, 04:47:24 pm
content: If you look at a picture of the board there are 4 banks of pins. These are the IO pins. The design is not the typical male to female pin. I was wonder how these work? How do you attach things to them?

author: rstofer
author_rank: Super Contributor
timestamp: January 17, 2022, 06:16:09 pm
content: I think you have to come up with the matching connector. I suspect it will be board-mount so you may need to build some kind of adapter if you want to wind up with standard headers.You might read the home page and find:QuoteThis is not what I would consider a 'friendly' board.If you look at the pictures you will find the board is built by Sparkfun and if you search their site, you will find the matching connectorshttps://www.sparkfun.com/search/results?term=alchitryPay attention to the board-to-board connector because all of the board mounted connectors are female and this requires a double male connector.

author: asmi
author_rank: Super Contributor
timestamp: January 17, 2022, 06:21:19 pm
content: Quote from: prophoss on January 17, 2022, 04:47:24 pmThey look like a standard high-speed connectors to me. Find out mating part number and make yourself a board if you want. They opted for high-speed connector in order to leave possibility of connecting something high-speed, but if all you want is a bunch of flying leads, you will need to either make or buy a breakout. This is still better than just using 0.1" headers because they preclude high-speed. I design most of my boards using similar connectors for the same reason - for low speed flying leads, additional connector is not a problem, but the reverse it not true.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 17, 2022, 07:04:35 pm
content: If you wanted to easily connect stuff to a board for experimenting/quick prototyping, then it's definitely not the right board for you. Sorry, but should have looked obvious when you ordered it. Yes those are high-density connectors. While you can find matching connectors, those are fine-pitch SMD and I don't see how you could avoid making your own board (or buying a ready-made one).

author: prophoss
author_rank: Contributor
timestamp: January 17, 2022, 07:14:46 pm
content: Ok, that sort of helps. What can I connect to this type of connector? For instance a screen? Maybe using a flat cable? This is very new to me. Could someone give me an example to go by?

author: rstofer
author_rank: Super Contributor
timestamp: January 17, 2022, 07:45:09 pm
content: I think you have two choices:Build a PCB with the matching connector(s) located at exactly the right spacing (and that may be difficult) orBuy one of the Sparkfun boards that seems appropriate and go from there.Personally, I would not recommend this board given the oddball connectors. They may simplify high frequency signaling but they are a mess for prototyping most everything else. Unless you can use the Sparkfun boards...https://www.sparkfun.com/products/16524https://www.sparkfun.com/products/16581Note that the prototype board should stack directly and leave female socket exposed for further stackingTutorialshttps://learn.sparkfun.com/tutorials/tags/fpga

author: asmi
author_rank: Super Contributor
timestamp: January 17, 2022, 08:04:59 pm
content: Actually I think this board has greater long-term potential once you move past the stage of blinking LEDs and will want to explore connecting something more high-performance. But you will have to start making your own daughter boards with custom peripherals - that's when this board design will really begin to shine. That said, FPGA on that board is not very large, so maybe at that point you will have to move to a larger device.