wd5gnr / verifla

Fork of OpenVeriFla - FPGA debugging logic analyzer to use with your designs - examples (so far) for ice40/IceStorm

Verifla

This is a fork of OpenVerifla (https://opencores.org/project/openverifla) that tries to do a few things:

1. Document some of the settings a bit better
2. Fix a bug where samples that changed on one clock were not handled properly
3. Add synchronous memory that is easier for some tools to infer
4. Some minor cleanups and plans for enhancements
5. C tool to read output and generate VCD directly (see C directory for build instructions)
6. Adds clock enable/qualifier (defaults to 1 so you don't need to specify it if you don't use it)
7. Adds armed and trigger outputs
8. Adds trigger qualifier (must be 1 -- set by default -- for internal trigger to work)
9. Adds exttrig (default 0) if you want your own trigger logic -- does not respect trigger qualifier as we assume you could do that yourself if you wanted to

Note on 6, 7, 8, and 9: The armed output goes high when the monitor state machine is running. The triggered output goes high when something triggers the state machine. The data sample clock only reads a sample when the cqual, the clock qualifier, is 1 (the default). So if you know your circuit only does interesting things when counter==0 for example you can set that as the clock qualifier. You can drive exttrig to 1 if you want to trigger with your own complex logic. For example, you could have a state machine read serial data and trigger when you see a certain serial character. For the internal trigger, you can inhibit it by setting trigqual to 0 (the default is 1). For example, you might only drive it high after some precondition to prevent an early trigger.

The PDF attached has some good information on it. However, a few things to note:

1. Do not set Run to 1 in your code unless your trigger is infrequent. If data constantly spews out of the FPGA, the JAVA code can not sync to it.

2. There are some strange unsquashed bugs. For example, on the Lattice iCe40 with Icestorm tools (at least) setting memory to 256 bytes and the trigger position to 128 causes a hang. Trigger positions at 127 and 129 are fine.

Possible Enhancements

1. Uart clock vs Sample clock (Uart clock >> Sample clock)
2. Clock Enable for sample clock (done)
3. Change post trigger samples to do post trigger memory words (or document to set huge #)
4. Java: Pick up Verilog file from template

Quick Start

1. Link or copy the verifla directory (the one under verilog) to your project directory
2. Copy config_verifla.v.template to your working directory and rename it to config_verifla.v
3. Make sure your Verilog tool will look in the verifla directory as a library
4. Make sure the search path for includes will look in your project directory first
5. Edit config_verifla.v in your project directory to se clock speed, baud rate, memory size, etc.
6. Write your verilog in the project directory.
7. Create a top_of_verifla module. Here are the signals:

• clk - Clock
• cqual - Qualifier for data capture clock (UART and other things use clk alone). If you don't want a qualifier, just set to 1'b1 (which is the default).
• rst_l - Active low reset.
• sys_run - High to arm logic analyzer. If you only want to arm from the PC, set to 1'b0.
• data_in - Your inputs. Group together like {led3, led2, led1, led0, count[3:0]}.
• uart_XMIT_dataH - Your RS232 transmit line
• uart_REC_dataH - Your RS232 receive line
• armed - digital output showing LA is armed
• triggered - digital output showing LA is triggered
• trigqual - Must be set to 1 to allow internal trigger to occur (default is 1)
• exttrig - Set to 1 to force a trigger (default is 0; does not respect trigqual)

8. Once running you can use the original Java program to create a .v file you will need to simulate or the C program (la2vcd) to create a .vcd you can read using a waveform viewer (like GTKWave)

Notes about using GTKWave

The C program creates a simple dump that has the entire capture data and also each byte captured. You can suppress the bytes (-W) or the aggregate (-B) if you like. However, you really want to have the signals broken back out like they are in your code.

Suppose you have 16-bits of data like this: counter8[7:0], led0, state[6:0]

It is easy to add the capdata[15:0] data to GTKWave. Then expand it into bits. Select the counter8 bits and press Combine Down on the Edit menu (or Combine Up if you are reversed endian). This will prompt you for a name so enter "counter8" and press OK. Now you'll have a counter 8 signal. Repeat for state. For the led0 signal, you can create an alias.

Of course, this is painful to set up every time so use Write Save File on the File menu. This will save the layout for next time you load a VCD with the same format.

Note about Quartus and possibly other synthesis tools

Quartus requires that you enable System Verilog for the config file parameters to work.

Many synthesizers will accept module definitions like this: module foo(input bar=1'b1);

Quartus appears to not accept these even in System Verilog mode. To work around this you can use top_of_verifla_nodef instead of top_of_verifla_nodef. In this case, you need to provide inputs (even if constants) for sys_run, cqual, trigqual, and exttrig.

The code has been lightly tested on a MAX10 FPGA and there is an example in the demos folder.