Log

Introduction Let me take a detour from the HDL and digital things and go back for a while into analog domain. For this whole system I’m building to be any useful, the signal from the guitar has to have enough amplitude to: Dominate the noise of the processing chain Use as much as possible the XADC dynamic range. In any case, I need something simple while also thinking I wouldn’t be able to respect myself if I do it in a circuit mounted into a breadboard. So, I took also the chance to learn the skill of PCB production in a long afternoon. ...

Introduction On this little project of making a guitar chain effect, the equalizer/filter will be a central component. The guitar has a particular spectrum and not all the 20KHz humans can hear are useful to be processed. In filtering out the unnecessary frequencies we get some benefits: All the spectral content is useful information, increasing the amount of signal we can process We are cutting noise, which usually is very wide spectrum, oftentimes modeled as uniformly distributed All of this translated into better signal-to-noise ratio (SNR) ...

Introduction It took me a while to come with worthy content, but here I am. I have been working on getting my FPGA board to sample analog audio with the internal ADC for a project proposed by a colleague as a way to learn the intricacies of digital design. Let me tell you straight: documentation about the ADC of this Artix 7 device does a great job at being confusing. I’m not ashamed to say that this is the part that took me the longest to figure, also considering the paranoia about damaging the components with non-compliant voltages. ...

Introduction Last time we did together a circuit using verilog to communicate to a I2S device. But we never delved into how to make a waveform for it. Now, don’t get me wrong: if you did the blinky led example while starting your first projects, this can be easily achievable for you: A square pattern is just zeros and ones A saw pattern is a counter from zero to max A triangle wave is a counter that goes back after hitting max or min values A sine wave is just some CORDIC… Now, we will not be using CORDIC and will not be doing simple counters. I want to show you a couple of tricks to generate a clean sine waveform that you can later compose to create more fancy sounds. ...

Introduction As you perhaps know, I’m working on this blog also as a way to log my learning journey. So, to support the lack of interesting peripherals on the Arty A7, I bought a set of modules for Arduino. Most of them quite uninteresting, but I got this I2S DAC module from Adafruit that implements the UDA1334A from NXP (datasheet). This device interest me the most among the ones I got from the assortment, because since I was a kid I wanted to make my own guitar effects (in fact, I believe many electronic engineers are born this way or similar), so the end goal is quite ambitious as you can see. But let’s start from something easy. ...

Introduction If you are a hardware engineer you need no explanation though, this is more for the programming guys who attempt to make things with an FPGA in the belief that is the next step of Arduino (I do think that though, so no judgment made here) As someone who wrote a lot of code in my young age (still loving fiddling with Linux kernel), I’m lucky I got the purpose of HDL. ...

Let me be brief, as this is just to fill the emptyness of a newly created blog: I want to learn new skills and take notes that can be shared with people in the hope they will find useful as well. In this blog I have the plan to showcase my personal projects on electronics and perhaps other fields, maybe adding some of the knowledge I have accumulated in the last years in the field (if it doesn’t break any NDA, of course). ...