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I think there are a couple of flaws in your code
Issue# 1:
As I said before, your code increments the counter on each clock pos edge whenever bit6 of input port is asserted.
Now, what's clk frequency? If this is in the kHz or MHz range you will indeed get random numbers from the counter: I don't think you could keep the switch pressed for a single clock period! You'd rather get thousands of counts for every push, even if you are very very fast.
Issue# 2:
IMHO, using out and readdata registers in that way is not good.
Replace = with <= for register assignments: e.g. out <= readdata;
See
http://en.wikipedia.org/wiki/verilog for explanation of difference.
I guess in this 2 registers case, the = assignment is logically and syntactically correct but is not exactly synthesizable: that's why the simulation works but the real system doesn't.
Apart this, I'd simply remove the 'out' register; readdata is enough.
Example:
(last is used to keep trace of previous pushbutton status and trigger the count only once)
output reg [ 7: 0] readdata;
input clk;
input [ 7: 0] in_port;
reg last;
always @ ( posedge clk )
begin
if ( in_port[7] == 0 )
readdata <= 8'b0;
else if ( in_port[6] and ~last) // count only if switch has been pushed right now
readdata <= readdata + 8'b1;
// no need for else statement; everything is unchanged
last <= in_port[6];
end
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Thank you for your help very much.
It work successfully.
Excuse me. May I ask another question?
It is not related with the above problem.
The following is the problem description.
Now, I have a DE0 board, uClinux kernel, NIOSII processor, and u-boot.
The version of uClinux kernel is uClinux-dist-20110603.
The NIOS II version is 10.1 and quartus II version is 10.1.
The u-boot version is u-boot-2011.06.
I want to download the .sof file to DE0 board and then boot kernel.
I have the three way to achieve the goal. I fail in one of them which is used the "bootm" command.
First, I don't use the u-boot to boot kernel.
Directly download the kernel to the memory and then boot kernel.
(I use the compressed image kernel which is not .gz file but through "misc.c" )
Second, I use the u-boot's "go"command to boot kernel.
Directly download the kernel to flash by using "flash programmer tool" of NIOS IDE. And then I copy the image kernel from flash through "cp.b" command. Finally, I key in "go" command booting kernel.(I use the uncompressed image kernel which is not through "misc.c")
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==>cp.b 02400000 01800000 400000
==>go 01800000
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Third, I use the u-boot's "bootm" command to boot kernel. It failed .
(I use the compressed image kernel which is not .gz file but through "misc.c")
1. I create the uImage through the "mkimage" tool.
The following is the settings
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mkimage -n 'linux- 2.6' -A nios2 -O linux -T kernel -C none -a 0x01800000 -e 0x01800040 -d zImage uImage
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The following is board information
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==> bdinfo
mem start = 0x01800000
mem size = 0x00800000
flash start = 0x82400000
flash size = 0x00400000
flash offset= 0x00000019
ethaddr = (not set)
ip_addr = 0.0.0.0
baudrate = 1 bps
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2. bootm command
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==>cp.b 02400000 01800000 400000
==>bootm 01800000 -
# # Booting kernel from Legacy Image at 01800000 ...
Image Name: linux- 2.6
Image Type: NIOS II Linux Kernel Image (uncompressed)
Data Size: 1457595 Bytes = 1.4 MiB
Load Address: 01800000
Entry Point: 01800040
Verifying Checksum ... OK
XIP Kernel Image ...
OK <-----------------------------
(stuck here.......) --- Quote End ---
Could you give me some suggestion.
Thank you very much.
ps.I know the another address setting which will move the kernel in bootm command. I also try it, but still fail.
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