What is the best signal interface for PC ?

[_q12x_]

-Was my answer clear enough after all? (as short as it was)

 

[marconi]

Hello. My#117 refers to my #115.

I think we have been at 'cross purposes':

Cross–purposes Definition & Meaning | Britannica Dictionary - https://www.britannica.com/dictionary/cross%E2%80%93purposes

 

[_q12x_]

Untitled 58.avi

www.electriciansforums.net

I actually made the entire movinglight program like I did it with arduino..... in binary format and then converted in hexa and finally converted to encrypted bin file; But because that counter is counting to 5, is only displaying only the first 5bytes in the program. Im still thinking.... I made some previeous tests before this moving thing here and I can lit every individual led in the matrix if I find its coresponding byte code. Im very close....like that.

 

[_q12x_]

also a second movie to show you the progress and the problems as well.

Untitled 59.avi

www.electriciansforums.net

 

[_q12x_]

Proteus sim p5 - I finished the logic to drive the Led Matrix Display

 

[_q12x_]

@marconi I believe you pressed a button and switch back and forth the letters already saved in the memory. You advanced 1 step that memory location with a press of a button. I observed/remember right?
Also I need help in this detail because is a bit too hard for me. Tell me how to advance to the next character.
Thank you.

 

[_q12x_]

Tell me how to advance to the next character in the RAM ? How you did it? I believe you pressed a button to do it, but how it was wired? please detail it for me. Thank you.

 

[_q12x_]

@marconi check this out, its on it's way before your package. It should arrive soon.
So I will have 2 RAM types to experiment with.

 

[marconi]

Before I wade in with any help(?) please clarify for me how you intend your logic to scan the LEDs of the 7 x 5 matrix. ie led by led, a column of 7 LEDs column by column left to right and then repeat or a row of five leds row by row top to bottom and then repeat.

My scheme is to scan the display column by column left to right and then repeat as in the attachment. In this test sequence the complete column of 7 LEDs is lit up, column by column.

 

[_q12x_]

Its not clear from my #125 movie?
here is the entire circuit diagram.

 

[_q12x_]

Please clarify for me how you intend your logic to scan the LEDs of the 7 x 5 matrix.

BECAUSE I had to deal with limited (8pin Outputs) number on the memory IC, I had to be 'smart' about it.
I linked 3 pins of the RAM to the RAM Decoder 74136 that in turn is controlling 7pins for ---column--- of the matrix. Then, the rest 5pins of the RAM chip, I linked directly to ---COUNT the lines--- of the matrix.
Also the Counter 7493 is counting to 7 (not to 5 as we made it in our first example). Im happy I get to this simple result, but I tried a TON of permutations, you probably understand. I hope is clear enough.
In short, I count the LINES from top to down 7 times, and I set the column bits per each count.
And I have the feeling my circuit and my logic here is exactly complementary to your circuit. Right? In my defense, I did whatever I could to make it work... and it is working., which is good. Right?

 

[marconi]

Now that you have clarified what I suspected may I suggest that you do not need to drive the 74138 by four data outputs of the RAM2732. Drive the 138 using the same 3 lines (1,2,4) of the 7493. This will still cause your display to be scanned line by line, top to bottom and then repeated. ie 7 lines

Now you have 8 data outputs. You can use the first 5 - D0 to D4 - of them to set the state of illumination state of each LED in a line. eg (00100) (010010) (10001) (10001) (11111) (10001) (10001) for the letter A

Now turn your attention to the address word which is 12 bits long A0 to A11. Use A0 to A2 (ie 1, 2 and 4) as now connected to the 7494 so that for any state of bits A3 to A11 the 7493 will cycle through 5 memory locations. These five memory locations are a unique group determined by bits A3 to A11. This means you can store in the RAM 2exp9 number of unique groups of 8 bit data outputs of which you will use 5 bits.

One could write the Address word A as ( A11, A10, A9......................A2, A1, A0) = (Character Identifier Address (9bits) Character Font Code Addresses(3bits))

The 7493 will always cycle through A2,A1 and A0 to output the 7 five bit line patterns of a character font. You only need to select which character font you want to display by setting the Character Identifier Address A11 to A3.

Thus letter A could have the Character Identifier Address 000 000 001 A2, A1, A0
Letter B could have 000 000 010 A2, A1, A0
Letter C ......000 000 011 A2, A1, A0
Letter D........000 000 100 A2, A1, A0

Thus by setting the Character Identifier Address you can pick a character to display. Of course you have to programme the five memory locations addressed by the Address Word A so that they contact the appropriate bit patterns for the seven lines which make it up.

 

[marconi]

Now that you have clarified what I suspected may I suggest that you do not need to drive the 74138 by four data outputs of the RAM2732. Drive the 138 using the same 3 lines (1,2,4) of the 7493. This will still cause your display to be scanned line by line, top to bottom and then repeated. ie 7 lines

Now you have 8 data outputs. You can use the first 5 - D0 to D4 - of them to set the state of illumination state of each LED in a line. eg (00100) (010010) (10001) (10001) (11111) (10001) (10001) for the letter A

Now turn your attention to the address word which is 12 bits long A0 to A11. Use A0 to A2 (ie 1, 2 and 4) as now connected to the 7494 so that for any state of bits A3 to A11 the 7493 will cycle through 7 memory locations. These 7 memory locations are a unique group determined by bits A3 to A11. This means you can store in the RAM 2exp9 number of unique groups of 8 bit data outputs of which you will use 5 bits for a line of 5 LEDs.

One could write the Address word A as ( A11, A10, A9......................A2, A1, A0) = (Character Identifier Address (9bits) Character Font Code Addresses(3bits))

The 7493 will always cycle through A2,A1 and A0 to output the 7 five bit line patterns of a character font. You only need to select which character font you want to display by setting the Character Identifier Address A11 to A3.

Thus letter A could have the Character Identifier Address 000 000 001 A2, A1, A0
Letter B could have 000 000 010 A2, A1, A0
Letter C ......000 000 011 A2, A1, A0
Letter D........000 000 100 A2, A1, A0

Thus by setting the Character Identifier Address you can pick a character to display. Of course you have to programme the seven memory locations addressed by the Address Word A - character identifier address in red- so that they contain the appropriate bit patterns for the seven lines which make up a character.

Slight correction inserted to text above.

 

[_q12x_]

...may I suggest that you do not need to drive the 74138 by four data outputs of the RAM2732. Drive the 138 using the same 3 lines (1,2,4) of the 7493. ...

This was truly very smart correction ! I didn't see it and I like it. I build it, tested and I confirm it works. Very logical !
- But for the rest of the explanation... uuuuggggh... I didnt understand from where I can switch the addresses. Please condense in another but very short and to the point explanation, more short than what you explained already (and I do appreciate the effort so far but I cant see any logic to follow). I read your text a couple of times with the circuit in the left, reading the circuit as well, but... really, I can not see any logical road to take. Try again, please.
- Also, in the same time I will try some more permutations, directly with the RAM chip, my usual testing way in the dark, until (IF) I find a result. I have an idea I wake up with, to try for testing.
And thank you so far.

 

[marconi]

I will try but not right now. What I will say though is that these technical problems, and our thinking about them, and coming up with possible solutions, and then testing them and learning from how they perform is how we learn profoundly.

I will show you in a video how I produce A and B when the ROM is addressed by the Gray codes 0000 and 0001.

(You know that this project including the use of the EEPROM is what the pupil I mentor and tutor had to solve himself - which he did with some explanations like I have provided you with - as a digital electronics project in his part-time Higher National Certificate Course (HNC) in electrical engineering. Thus, it is quite demanding so I would not beat yourself up if you find it difficult right now).

 

[_q12x_]

Here is your very smart correction. As you can see there are other 3 free nodes on the 7493 wires to the ram. Those nodes I connected to RAM A9,A10,A11, as you suggested in your explanation. As you can see it in this picture right now, the matrix is displaying correctly the letter A from the RAM. But if I connect those nodes to A9-11, it will NOT display anything. Sign that the addresses have changed.
I want to change the addresses (to iterate) from a single button, to advance 1 addr by 1 click of the button. And on each address will be a new 'letter' or a 'word of bytes'.
Im thinking to an additional demultiplexer IC linked to all the addreses and my button behind this IC. Thats the logic I can imagine at this point.
Im curious if you made your project with this exact number(and names) of chips or they were more that you didnt mentioned? Also how much time it took you to make it?

 

[_q12x_]

I understand the problem and what is to be done. No need for further clarifications !
So, I wish from now, good morning there and drink peacefully your English tea.
I actually throw this question to my other forum and my good american friend there completely understood me and give me straight the answer I was looking for. Read it for yourself as well since is very short and very to the point.
Led Matrix Display and switching RAM address problem - https://forum.allaboutcircuits.com/threads/led-matrix-display-and-switching-ram-address-problem.188934/
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The clarification:
This particular 2732 EPROM memory chip has 12 address pins, (A0-A11) this means 2^12 = 4096 addresses available
And 1 character is requiring 7 addreses to be displayed, by that 74LS93 counter.
for example letter A = 70 89 8A FB 8C 8D 8E
This means 4096/7 = 585 characters to completly full up the entire memory.
There are 26 letters in the alphabet and 10 numerals from 0 to 9.
In total 36 characters to be displayed.
36*7 = 252 addreses in total for the entire set.
where 2^8 = 256, this means 8 addr pins to be used.
----
I am still looking like an idiot to the circuit and still have no clue how to proceed. Although I understand now that I have to somehow count each 7 lines for 1 character, I still need probably another counter to travel to the next 7 pack of addresses that contain the next character symbol in the memory. What should I add to 1-aquire the last address of the character and then 2-switch to the next pack of 7 addr ? Very complicated, especially for me that I am not that good with logic gates and analog IC's in general.
---
One of my greatest ideas is to add a BIG counter. One that is counting to 256 (or 252) and then it is resetting back to 0 and starts again. I need it NOT to count by itself, but somehow stop from 7 to 7. And when I press a button, it will enable to get to the next 7 pack and stop there as well. In this time, it will get to 0 and count to 7. But if it is at addr 21 for example it will count to 28 and then reset to 21 again, count up to 28 and so on. So it will strobe the character at that particular sector. All these details, I didnt figure out, I only imagine them.

 

[_q12x_]

To construct an 8 bit counter to connect to A11 (msb) through to A3(lsb) on the 2732 cascade two 7493s together so that Qd of the first ic connects to clkAbar of the second. Remember to connect Qa to clkB bar on each chip.

Use the pulse circuit in # to produce a negative going pulse upon depression of the push button and connect it to clkAbar of the first ic.

Ok, thank you. So it was a secondary 7493 IC linked to the same clock. Very ingenious from you mister @marconi. I will construct it.

 

[_q12x_]

Ok, now I need 8 address pins to cover, for all 36 characters.
I will need another demultiplexer I guess..... right?

 

[marconi]

My #109 For the pulse generator using a push button,

There are two independent counters. One free running to cycle through A0 to A2 and the seven lines of the 7x5 using the 74138 and then the one I just described to increment upwards on each press of the push button through A3 to A11.