SPI Block

[KT Chiam]

Hi. I'm trying to use SPI in my application. For now, I just try to write a byte to SPI MOSI and check the output at oscilloscope. The output is not what I expect (see attached scope capture. yellow is SCLK, magenta is MOSI. there are too many clocks for SCLK? Can someone guide me how to use the SPI block? 

Thank you

[charli va]

Hi KT, here you have an excellent documentation by Obijuan (in spanish but i think you could translate easy with chatgpt or similar):

https://github.com/Obijuan/Cuadernos-tecnicos-FPGAs-libres/wiki/CT.5:-SPI-esclavo

https://github.com/Obijuan/Cuadernos-tecnicos-FPGAs-libres/wiki/CT.6:-SPI-maestro

I hope should be useful for you!

El mar, 21 may 2024 a las 17:57, KT Chiam (<kokthia...@gmail.com>) escribió:

Hi. I'm trying to use SPI in my application. For now, I just try to write a byte to SPI MOSI and check the output at oscilloscope. The output is not what I expect (see attached scope capture. yellow is SCLK, magenta is MOSI. there are too many clocks for SCLK? Can someone guide me how to use the SPI block? 

Thank you

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[Democrito]

Hi KT,

The problem is that you are sending a square wave to the "start" pin. That pin operates with one tick (a single clock cycle). There is a module that produces a tick for each rising edge of a square wave.

I attach your corrected circuit, you will see the module that I mentioned and that you can see in this image.

In this way, for each rising edge of the square wave it will generate a single clock cycle (tick).

If you load the circuit I attached, you have two options.

1.) I don't have your board, so you have to select it (Select -> Board -> ICE40-HX8K...)  And then you have to redefine the pinout you chose (for the LEDs, SCK, MOSI, etc).

2.) When you open the circuit attached, click on "Convert" and copy the module (click on the module and then "control C") that I have indicated in yellow in the image above. And then you insert it into your circuit (control V) and connect it as shown in the image.

Make sure Icestudio is configured to work with your board; This is important and you can see it in the bottom right corner.

If you have any problems with this, let me know and I'll try to be more graphic.

I have tested the circuit I attached and it works perfectly.

Greetings.

[Democrito]

I leave you a test image in which you can see that it works perfectly.

Most of the time, whether you design with Icestudio or directly in Verilog, internally it needs a single clock cycle, to compare, count, give the start signal, etc.

[charli va]

Thanks Democrito !

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[Democrito]

Thank you Carlos for this program and that it has given me so much life and has allowed me to meet such interesting people!

Now let's see if KT can get its circuit working. Any problems or questions you have KT, please don't hesitate to comment.

[KT Chiam]

Hi All,

Thank you very much and appreciate help from all of you. The circuit is working perfectly after the correction. 

By the way, I try to dig further into the blocks. How can I copy the comments for translation?

[Democrito]

I don't know if there is any method to translate directly from Icestudio, I think there is (from English to other languages) but I have never tried it.

I hope another user can answer this question for you.

Anyway, I'll show you how to copy and modify any text you find.

If you are on the main page of the circuit, all you have to do is double click on the text.

And if you are inside a module, you must first open the lock to be able to do what I mentioned above. In this animated image you can see exactly what I'm talking about.

In this other animated GIF I show you how to create and modify an informative text. In this case I manually translate the text.

Inside the info box I do "Control A" (select all) and then "Control C". I paste it into a translator and when they translate it for me I copy it. Going back to the code box I select everything and do "Control V" (paste).

On the other hand, notice that when you double-click on the text, the information box appears, as explained above. And if you double click on any corner or side of the info box, only the text appears and the info box disappears.

When inside an infobox, you can use Markdown notation.

[Democrito]

In the previous post, if you read "code box" I meant "information box"

[KT Chiam]

Hi,

Just want to share that I have found it. Just click the lock icon and it will unlock. Thank you.

[Jesus Arias]

Hi,

Looking at your capture I can see the clock edges are the opposite of what is usually expected:

- Bits changing on falling edges

- Bits sampled on rising edges

So, I think the SCK signal should be inverted before attaching it to an external device, just in case...

Regards

[KT Chiam]

Hi Charliva,

Thank you, the guide is excellent. 

I tried to download and open some of the examples, but it will result in error. Is it newer version can't open older version code? I have trouble to find the icons based on the guide. Thank you.

[charli va]

Hi KT! what are the links that not working? this is an Obijuan's repository and i don't know if are up to date but i think  Obijuan has been  updating all of his repositories and documentation to the new version of toolchains.

Be careful if you are using some automatic translator, because some times could be change links.

If you have  doubts tell us and we try to help you.

Have a nice day!

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[KT Chiam]

Hi Chatty, 

It seems to be working now. May be there was an error when I downloaded previously.

I could not find the code blocks from the Jedi-master collection. For example, see attached capture. Is it just copy the block and paste into my own code?

Also, what is the difference between Input / Output Label vs Paired Labels?

[Democrito]

Hi KT,

1.) "It seems to be working now. May be there was an error when I downloaded previously."

- It could be what you say and it could also be that Icestudio is not loading the circuit. When this last case happens, try it several times.

2.) "I could not find the code blocks from the Jedi-master collection. For example, see attached capture. Is it just copy the block and paste into my own code?"

Yes, 

- https://github.com/FPGAwars/Collection-Jedi/releases or click here: Source code [zip]

- Yes, you can copy and paste the block or blocks, whether from a collection or another circuit. It is very common to do so.

3.) "Also, what is the difference between Input / Output Label vs Paired Labels?"

- There can be pairs of labels (for each input one output) to facilitate connections because it is very common for them to be two by two, and they can also be individual because, for example, an input label can go (for example) to several of exit.

Greetings.

[Democrito]

The labels replace connecting wires and are used to make the circuit look "cleaner." An input tag is linked to an output tag or to multiple output tags as long as they have the same name.