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  Alchitry Cu and Io Pulldown Resistors
Posted by: Geo747 - 02-26-2019, 09:37 PM - Forum: General Questions - Replies (3)

I've been trying to get the Io board to work with the Cu today. I'm using verilog and Icecube2 with the alchitry loader (not using the alchitry ide). I'm trying to set up a .pcf file for the IO and have all the LEDs working correctly but cant get the switches or buttons to work. I believe this is because I need to set the inputs to have pull down resistors, as per the schematic, however I cant find any documentation of the iCE40-HX8K that suggests it has pull down resistors available on its inputs. In the icecube2 pin constraints editor only pull up resistors are available, and they havent helped in my scenario. When I have the pullup enabled, I just get a constant high logic level from that pin, and when the pullup isnt enabled it has erratic behaviour and will turn on or change state when i touch the button's casing, without actually depressing the button.

If someone knows what im missing to get it to work that would be much appreciated.


  Cu - how to start?
Posted by: wing - 02-24-2019, 06:46 PM - Forum: General Questions - Replies (5)

Hi ,
   Just received the Alchitry Cu, look great.
May I ask how to get started? It seem the tutorials are still for "mojo v3" and using Xilinx tools.


  Alchitry Io Switches with Au
Posted by: garthberry - 02-22-2019, 03:22 PM - Forum: Tips and Tricks - No Replies

After trying to get the switches (DIP and pushbutton) Alchitry Io working for a little too long it finally occurred to me that pulldowns need to be enabled for each of the pins attached to a switch. If pulldowns are not enabled the pin will typically float high. The pulldown resistor can be enabled on a pin by pin basis in the  constraints file as follows:

set_property PACKAGE_PIN C4 [get_ports {dip_sw[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {dip_sw[0]}]
set_property PULLDOWN TRUE [get_ports {dip_sw[0]}]

  Clocking with Lattice Parts
Posted by: samuelcomeau - 02-22-2019, 06:25 AM - Forum: General Questions - Replies (2)

So with the Mojo, the way to get new clocks was to use coregen via the awesome installed button. Since Cu is a Lattice part there is obviously not a coregen option. Therefore, how do I get my higher or lower clock signal?

  Headers. (First!)
Posted by: samuelcomeau - 02-22-2019, 01:26 AM - Forum: General Questions - Replies (7)

So I've had the Alchitry Cu for a few days. Great looking board, I'm excited to get the software up and running. Just one question. How do I connect anything to it? I don't see my comfortable headers and I feel completely paralyzed. 
Objectively, I know there is a solution to this problem and that it wouldn't require too much work on my part, but is there a simple solution to go from the super whamadine headers to my comfortable breadboard friendly ones? 
(P.S. I don't hate the new headers, my Mojo has so many bent pins it's starting to look like a porcupine.)

  Welcome to the new forum!
Posted by: alchitry - 02-21-2019, 05:47 PM - Forum: Announcements - No Replies

Welcome to the new forum! After the old forum was basically made useless by an overflow of spam, this new one will hopefully fare better.

Note that you will need seperate logins for the forum and our store.

You can still access the old forum in its "read only" state here https://forum.embeddedmicro.com/