Upduino Verilog Examples

These are a few examples for the Upduino v2.0 (Lattice ICE40 device) written in Verilog and designed to be used with icestorm. The examples are designed to be part of a very small Verlog/FPGA class. Some additional hardware is required. We used the custom made board from https://github.com/akaFunk/UpduinoLEDButtonExpander, but a bunch of buttons and LEDs on a breadboard will do the job.

There are also very simple build scripts in each directory which can be run to build the whole project and flash it onto the Upduino.

Chapter 1 - No Logic

This examples just shows how a bare metal Verilog file looks like. It just inverts a button and routes it to an LED. This example also contains a couple of files on how to simulate the verilog code using Icarus and gtkwave.

Chapter 2 - Simple Logic

This example shows basic logic in Verilog. It takes two buttons as inputs and only if both are pressed the LED lights up. The logic is implemented using the assign statement.

Chapter 3 - Array

This is the same example as from chapter 2, but it is using an array for the two buttons instead of individual wires.

Chapter 4 - Simple Logic using always Block

This example shows exactly the same as the one before but implements the logic combination in an always block. It also introduces the if clause.

Chapter 5 - Blink

We introduce the clocked always block and implement a counter. If the counter reaches a specific value the LED is turned on, while it is turned off otherwise. This example additionally shows how to initialize the internal clock source of an ICE40 FPGA.

Chapter 6 - Statemachine

A simple state machine is introduced as state machines are crutial components in FPGA/CPLD design. The state machine has four states. In each states it will light up one of the four LEDs. The states are ordered in a circle and a jump between two states happens when the button corresponding to the current light up LED is pressed.

Chapter 7 - Chaser Light

The state machine from chapter 4 is modified to not jump between the states by a press of a button, but instead a counter. This turns it into a chaser light.

Chapter 8 - Submodule

Same functionality as the example from chapter 1 except a submodule is used to implement the inverting function.

Chapter 9 - iCEstick

This is the statemachine from chapter 5 but for the iCEstick. The only two differences are the pcf file for the pinout and the used clock source. While the Upduino v2.0 is using the internal HFOSC, the iCEstick uses the external 12 MHz oscillator.

Pinout

Below is the pinout used for both the Upduino v2.0 and the iCEstick. The buttons are low-active, the LEDs are high-active.

| Function | Upduino v2.0 | iCEstick | |----------|--------------|----------| | LED1 | 46 | 44 | | LED2 | 3 | 47 | | LED3 | 9 | 56 | | LED4 | 13 | 61 | | BTN1 | 47 | 45 | | BTN2 | 4 | 48 | | BTN3 | 11 | 60 | | BTN4 | 21 | 62 | | CLK | (HFOSC) | 21 |