órgano de expresión y combate cnt lanzarote 7. cnt lanzarote. hoja informativa cnt lanzarote 7
Counters2020/09/16 · •up/down signed nbit counter (default 8 bit) Counters add 1 select + or -...
Transcript of Counters2020/09/16 · •up/down signed nbit counter (default 8 bit) Counters add 1 select + or -...
Counters
Last updated 9/16/20
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Counters
These slides review the design for several types of counters
Upon completion: You should be able to design various types of counters
(up/dn/signed/unsigned/mod)
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Counters
• Up Counter
• Count in binary• 0000 → 0001 → 0010 → 0011 → 0100 … 1111 → 0000 …
b0 b1 b2 bn-1
D Q
QB
RSTB
D Q
QB
RSTB
D Q
QB
RSTB
D Q
QB
RSTB
clk_in
rstb
What’s wrong with this solution
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• Counter - n bit - unsigned
Counters
why?2 - reasons
cast
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Counters
• Counter - n bit – unsigned – (default)
adds 14 bits, hex 1
4 FF’s
adder logic
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Counters
• Counter - n bit – unsigned (6 bit version)
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Counters
• Counter - n bit – unsigned (6 bit version)
reset counting
wrap
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Counters
Mod counter
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• Mod 11 counter
Counters
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Counters
• Mod 11 counter
control selection ofcnt+1 or 0
add 1
check for < 0cnt – 10 (4bit, hex a)
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• Mod 11 counter
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counting mod11 wrapreset
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Counters
Up/Down counter
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• up/down signed nbit counter
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• up/down signed nbit counter (default 8 bit)
Counters
add 1 select + or -
subtract 1cnt & 1 → a bcde fgh11fd → + 1 1111 1101
n opqr stuv
cnt - 1
subtract 1Shift and concatenate 1 2x + 1Add -3 + -3
2x – 2
Only select upper bits → /2 x - 1
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• up/down signed nbit counter (6 bit test)
Counters
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• up/down signed nbit counter (6 bit version)
Counters
reset counting up
transition to negative
counting down
transition to positive