Community
cancel
Showing results for 
Search instead for 
Did you mean: 
SS5
Novice
1,413 Views

FIFO:How to slow down the clock Frequency from 50 Mhz

once I enable your counter, it is writing at full clock speed to the fifo

once the fifo is full, the counter just continues counting

by the time it start reading and printing the first value to the serial port, the fifo is probably already overflowing, as I did print some hello word message. Printing to the serial port is very slow compared to the counter filling up your fifo, and counter counts at something like 50MHz I guess (?)

* once the fifo starts overflowing, not all counter values will go into the fifo, as it is full, and you're only slowly reading the values from the fifo

0 Kudos
17 Replies
JOHI
New Contributor II
100 Views

Hello,

50 Mhz is the clock speed used by the CPU to process assembler instructions.

Instructions can require multiple clock pulses, this depends also on the cpu type.

​You are looking at a way to slow down the loop:

 

#include <stdio.h> #include <unistd.h> int main() { while (1) { printf("Hello from Nios II! \n"); usleep(1000000); } return 0; }

Best Regards,

Johi.

 

SS5
Novice
100 Views

I have added "usleep(1000000)" but printing speed is slow but i am getting correct answer.

NIOS_console.JPG

Can u check my FIFO design.

FIFO_design.JPG

 

 

GuaBin_N_Intel
Employee
100 Views

​I think the best way to control the flow of counter instead of slowing down the whole system. Probably you use the almost full signal from the FIFO to stop or disable the write signal from the counter.  Currently ,the module "block count" always receive data from counter regardless of any condition. Hope this helping you.

SS5
Novice
100 Views

Thanks for your response.

I am new to the altera.

 

>>Probably you use the almost full signal from the FIFO to stop or disable the write signal from the counter.

How it can done , can you explain me briefly.

 

Thank you

GuaBin_N_Intel
Employee
100 Views

It's harder in explanation ​if you design it in schematic. I make it simpler here:

 

1) Invert almost full signal from FIFO

2) "ANDed" it with the enable of counter

3) Drive output of "ANDed" signal to both of write FIFO and enable of counter. This is to halt the transfer completely.

SS5
Novice
100 Views

Did you mean to create own FIFO IP ?

Qsys_FIFO.JPG

1) Invert almost full signal from FIFO

2) "ANDed" it with the enable of counter

3) Drive output of "ANDed" signal to both of write FIFO and enable of counter. This is to halt the transfer completely.

 

Sorry to ask silly questions. In NIOS, i need to do ??

GuaBin_N_Intel
Employee
100 Views

The method does not involve any NIOS software or C coding. It is done through logic level. You have to modify the circuitry in the schematic and use primitive logic to construct.

GuaBin_N_Intel
Employee
100 Views

SS5
Novice
100 Views

Really sorry, i am not able to understand your logic level flow. can you explain in a better way like schematic diagram.

 

I need your help to complete this process. But Finally, i need to communicate with NIOS. Because through WIZNET i need to communicate with PC.

 

Thanks

SS5
Novice
100 Views

But Finally, i need to communicate with NIOS. Is it possible with designs building with primitive logic diagrams ? ?

GuaBin_N_Intel
Employee
100 Views

Just checked that the Avalon FIFO memory could not export the "almost full" signal resulting you could not use it as control signal. It is only accessible through IP API or SW control. So, you have to read it from NIOS and then determine the enable signal from PIO. In schematic, connect the "enable" to both counter and write FIFO. Refer to example code for FIFO control in the UG

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug_embedded_ip.pdf, 20.5.2

 

SS5
Novice
100 Views

Thanks for your reply.

Same thing i have followed.

 

Enable signal given from PIO

connected enable to both counter and write FIFO. In NIOS same data is printing continuously for certain cycles. Please clarify me how to sort it out.

 

Design as follows

Counter Verilog Code

module Counter( input clk, input enable, input reset, output reg[31:0] Final_value, output reg trig ); reg[31:0] counter_out; reg [7:0] temp=0; reg [31:0] counter_result; wire temp1; wire temp2;   always@(posedge clk) begin if(reset) begin trig<=0; temp<=0; counter_out<=0; end else if (enable==1'b1) begin counter_out<=counter_out+1; temp<=temp+1; if(temp==25) begin temp<=0; trig<=~trig; end end   assign temp1=trig; assign temp2=temp1&&clk; always@(posedge temp2) if(reset) counter_result<=0; else begin counter_result<=counter_result+1; end always@(posedge trig) if(reset) Final_value<=0; else begin Final_value<=counter_result; end endmodule

Schematic Design

Trig_block.JPG

 

NIOS CONSOLE, Same data printing For certain cycles.

NIOS_console.JPG

GuaBin_N_Intel
Employee
100 Views

Have you tried to use and understand the example code and register map given in the FIFO API? What you need to do is

1) ​Set the almost full threshold using initialization : altera_avalon_fifo_init()

2) Monitor the read status of FIFO : altera_avalon_fifo_read_status() and its status description can be referred to 20.5.1 Software control=> "i_status"

 

 

SS5
Novice
100 Views

Hi

 

On-Chip Memory Size is 4096

FIFO Depth : 1024

 

So, have i have set the

# define ALMOST_EMPTY 1 # define ALMOST_FULL 1000 //FIFO Depth 1024

The ALMOSTEMPTY and ALMOSTFULL printed in the console are correct.

# define ALMOST_EMPTY 1 # define ALMOST_FULL 1000 //FIFO Depth 1024   int main() {   int result,i=0; // Reset the FIFO's IRQ History register. * altera_avalon_fifo_clear_event(FIFO_0_IN_CSR_BASE, ALTERA_AVALON_FIFO_EVENT_ALL);   int code = ALTERA_AVALON_FIFO_OK; code= altera_avalon_fifo_init(FIFO_0_IN_CSR_BASE, 0x3F,ALMOST_EMPTY,ALMOST_FULL);   IOWR(ENABLE_PIO_BASE, 0, 0x1); printf("STATUS = %u\n", altera_avalon_fifo_read_status(FIFO_0_IN_CSR_BASE,altera_avalon_fifo_read_status)); while(1) { result=altera_avalon_fifo_read_fifo(FIFO_0_OUT_BASE,FIFO_0_IN_CSR_BASE); printf("%d\n",result); } return 0; }

In NIOS console,

 

STATUS =16

result: 0

 

Suggestion Please

SS5
Novice
100 Views

I have attached the Nios Screen-shot.

 

I am getting all data "0"

 

 

Nios_code.JPG

 

GuaBin_N_Intel
Employee
100 Views

printf("STATUS = %u\n", altera_avalon_fifo_read_status(FIFO_0_IN_CSR_BASE,altera_avalon_fifo_read_status));

 

T​he fifo status isn't right. You have put the same function into the function argument. Refer to table 206, to read back all of bits, use the following command:

 

printf("STATUS = %u\n", altera_avalon_fifo_read_status(FIFO_0_IN_CSR_BASE,altera_avalon_fifo_status_all));

 

To debug, please put this status command before starting the transfer and after enabling the transfer.

 

SS5
Novice
100 Views

init_input_fifo(); IOWR(ENABLE_PIO_BASE, 0, 0x1); printf("STATUS = %d\n", altera_avalon_fifo_read_status(FIFO_0_IN_CSR_BASE, altera_avalon_fifo_status_all)); level=altera_avalon_fifo_read_level(FIFO_0_IN_CSR_BASE); printf("\nLevel=%u\n",level); if(level !=0) { for(i=0;i<=500;i++) { //result[i]=IORD_ALTERA_AVALON_FIFO_DATA(FIFO_0_OUT_BASE); data[i]=altera_avalon_fifo_read_fifo(FIFO_0_OUT_BASE, FIFO_0_IN_CSR_BASE); printf("data=%lu\t",data[i]); } }   printf("\n Full=%d\n", altera_avalon_fifo_read_almostfull(FIFO_0_IN_CSR_BASE)); printf("Empty=%d\n",altera_avalon_fifo_read_almostempty(FIFO_0_IN_CSR_BASE)); }

Now my code is right.

Reply