11:55 <Athas> Hi, I got an icestick with an FPGA. I have all the software running, and I can compile Verilog to bitstreams and load it, and it works beautifully.

11:56 <Athas> However, is there a simple way of communicating with the FPGA while it is running? I know (roughly) how to interact with the pins in Verilog, so I could just connect some wires, although I'm not sure how I'd connect that to a PC.

11:56 <Athas> I don't have any specific projects in mind just yet; I'm just playing, and I want to send it some data and get some data back.

11:57 <sensille> UART is easy

11:57 <jeanthom> +1 UART

11:57 <sensille> serial interface

11:58 <jeanthom> it's just two wires, plenty of example code online, and a USB to UART adapter is really cheap (if you don't already have one at home)

11:59 <Athas> UART is those two-by-six pins at the end of the icestick?

11:59 <jeanthom> ooooh there's actually no need for external hardware on the icestick

12:01 <jeanthom> Athas, yes it could be, the 2x6 connector is a PMOD connector

12:02 <jeanthom> but since you got an USB FTDI chip you don't really have to bother with that

12:02 <jeanthom> Athas, https://github.com/cyrozap/iCEstick-UART-Demo

12:04 <Athas> jeanthom: thanks! But what does it mean that it has an FTDI chip? That I can do the serial connection over USB?

12:06 <Lofty> Yep

12:06 <Lofty> The chip handles the translation for you

12:08 <Athas> Great!

12:08 <Athas> That's also how it worked when I played with Arduino a decade ago, but I was unsure how raw these FPGAs would be.

12:11 <noopwafel> it is a nicety of some of these development boards, that the FTDI chip has a second channel connected to FPGA pins :)

12:37 <Athas> Thanks, the programming from that example seems to work! Now I just have to figure out how to fiddle with the serial connection in macOS...

12:40 <Athas> Figured it out! Great!

12:40 <Athas> Hobbyist FPGA tooling has been much more pleasant than the proprietary hellscape I had imagined.

12:41 <Ultrasauce> don't worry the latter is always an option

12:43 <whitequark> lol

12:46 <Athas> I do find it a little funny that yosys's output is so verbose that it even separates it into titled subsections.

12:54 <whitequark> that's fairly common for synthesis tools

12:54 <whitequark> i mean, Diamond even gives you a pretty HTML with frames and folders

12:56 <daveshah> I have been thinking about doing something like this for when nextpnr gets fancier timing analysis, tbh

15:00 <Athas> Oh, the Icestick also has some RAM on board, it seems. This is getting better and better.

15:00 <Athas> "The iCE40 device architecture provides resources for memory-intensive applications."

15:00 <Athas> Well, it has 68Kbit, as far as I can see.

15:00 <Athas> s/8/4/

15:06 <jeanthom> Athas, every FPGA chip has a bit of built-in RAM, somewhere in the 1kB-10MB range depending on the FPGA model

15:07 <Athas> I read that the Icestick FPGA uses RAM to store its configuration. Does that mean some of the RAM will already be used?

15:08 <zyp> no, you're mixing up different kinds of memory

15:08 <jeanthom> Nope, it's two separate things

15:08 <Athas> That's what I suspected. Good.