n**h
发帖数: 694 | 1 小弟不是电子的，最近一个小电路需要解决
从3个端口输入“000,001,010...111"的TTL数字信号。
希望输出到8个端口0，1，2...7，每个端口的高低(TTL)决定于输入端口二进制数字。
比如输入三个端口分别是”高低高“(101)那么输出端口5就是高，其余为低。如果输入
是010,那么输出2就为高。
我知道这一定是很简单的问题，那位帮忙指教一下。 | z*****n
发帖数: 7639 | 2 74ls138: 3-input/8-output decoder
http://rabbit.eng.miami.edu/info/datasheets/74LS138.pdf
【在 n**h 的大作中提到】
: 小弟不是电子的，最近一个小电路需要解决
: 从3个端口输入“000,001,010...111"的TTL数字信号。
: 希望输出到8个端口0，1，2...7，每个端口的高低(TTL)决定于输入端口二进制数字。
: 比如输入三个端口分别是”高低高“(101)那么输出端口5就是高，其余为低。如果输入
: 是010,那么输出2就为高。
: 我知道这一定是很简单的问题，那位帮忙指教一下。
| n**h
发帖数: 694 | 3 perfect!!Thanks a lot!!
【在 z*****n 的大作中提到】
: 74ls138: 3-input/8-output decoder
: http://rabbit.eng.miami.edu/info/datasheets/74LS138.pdf
| f*****0
发帖数: 489 | 4 if you step out of the problem, you will notice that it is simply a
dataconversion issue: for any input (in your case, a 3-bit input), you will
need to find a corresponding 8-bit output.
your problem is very simple: it is absolutely linear and a 138 is a perfect
solution for that.
what if your input isn't perfectly linear? for example, you may do a current
to temperature conversion where the current isn't exactly linear to the
temperature?
In that case, you can use a very simple but highly effec | f*****0
发帖数: 489 | 5 you can also form a arithmetic cpu with such a memory chip.
let's say that you want to do a 3bit apu that takes two 4-bit numbers (A and
B) and do (4) arithmetic operations on them.
so you need a memory chip with 8-bit address line: the first 3 address lines
are for the first data input A, and the second 3 address lines for B. the
the last two address lines are for the operator (00=addition, 01=subtraction
, 10=multification, and 11=division).
all you need to do is to program the right results i |
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