Hello, I have a problem and I'm asking for help. I want to implement this code on the nexys 50 a7 board. The idea of how the board should work is that if I enter an eight-bit number on the switch, the segment display will show me what works. But when you click the button where the rd_uart variable is, nothing happens. it should be downloaded to the PC through putty. When typing on the keyboard, it should be displayed on the segment board, but only the tx light on the board flashes, but the rx vbc led does not flash, do you know where the problem is? I am sending a link to gifthub. : https://github.com/KrizLuk0/digital-electronics1/tree/main/UART_FPGA/project_U25
Divide your problem and debug:
- build an UART test transmitter to transmit a known pattern every e.g. 100 ms
- if the tx works connect a counter/fsm to the transmitter and send a more complex pattern (e.g. 1-2-3-4-...)
- if the counter/fsm output is the same as you expect it, connect your keyboard to the fsm...
nothing happens
Your task sounds reasonably simple. Your solution looks incredible complicated. Why the heck do you need a fifo here? All interaction ist done by humans, so it is really sllllllooooowwwwwww regarding the 50MHz FPGA.
if I enter an eight-bit number on the switch
What switch?
the segment display will show me what works.
In what manner?
But when you click the button
Which one?
the button where the rd_uart variable is
???
it
What ist "it"?
should be downloaded to the PC through putty.
Putty is a software running on the PC. So maybe it should be received and visualized by Putty.
When typing on the keyboard
What keayboard?
it should be displayed on the segment board
In what manner?
So you want do display 2 informations on the 7seg display: the switches and the RX value? So: what has priority on the 7seg display?
I understand your description this way:
- from FPGA to PC
- you enter some binary code on the dip siwtches
- this code is displayed on the 7seg display (in hex? or decimal?)
- when you press a button the code is sent via async serial (and afterwards somehow displayed on the PC Screen)
- from PC to FPGA
- when you hit a key on the PC keyboard, some (ASCII?) code is sent via serial
- the FPGA receives the data and shows it in some manner on the 7seg display
Is that correct?
Yes, exactly as you describe, but the implementation does not work
but the implementation does not work
Split up the whole job in a TX and a RX section like Rick D. already advised.
What about simulation? The simulator is the debugger for your VHDL design. Do you have a test bench? What does it look like?
I'm not sure if I understand correctly. Are you saying that I should separate the FIFO because it's unnecessary? Then, can I connect the output from RX (DOUT) directly to the segment display? And similarly, connect the switches directly to TX?
Are you saying...
Correct, thats would be my direction. Why using a fifo when nothing is stopping you from writing the display whenever you want. An adjustment of a new value takes longer for sure than sending the last value.
But as said: simulate your design before going on hardware.
Have a look at my RS232 implementation. Think about it and why it needs much less lines of code than yours: http://www.lothar-miller.de/s9y/categories/42-RS232