40110 with rotary encoder

[Wokyerdog]

Obviously from the title im attempting to drive a 7 seg led display (up and Down) with a rotary encoder.

Vcc goes through a 47k to pins 7 and 9 as does the A and B leads from the encoder respectively. The middle lead from the encoder goes to ground. From what i could dig up from googling the hell out of encoders and this particular chip, i feel this is correct Input setup.

What i have a question about is the toggle enable, latch enable and reset. If I just hook these to ground, can I still turn the led number up and down?

-tim

 

[crutschow]

Yes, you connect /TOOGLE ENABLE, LATCH ENABLE, and RESET, to ground for the chip to count.

But I don't think your connection of the encoder will case the chip to count up or down depending on the direction of rotation as you want. Most rotary encoders have a quadrature output and you have to decode it with a circuit such as this (second circuit), which will give the correct up or down clock pulses depending upon the direction of rotation.

Without such a circuit the counter will just count up 1 count and then down 1 count for each pair of pulses from the encoder, independent of its direction of rotation.

 

[Wokyerdog]

Wow...i never realized that one input would require a whole chip to "decode" in order for it to function properly. Times liek this I don't mind being the new guy. I like discovering stuff like this :-D

I'll be back in the lab tomoro to give it a shot. I have a feeling that they wont have that chip in the drawer so ill have to order it.

Eventually I want to control 3 7seg with the turn of this encoder and have it count to 999 (and back down obviously). I'm assuming that I'll need 3 of the 40110 chips (one for each 7seg). I can also deduce that the borrow/carry pins will be used to control the other 2 chips. I'm also assuming that the reset (which i will use eventually) will be triggered with a tactile switch and a pull-down resistor.

-wok

 

[crutschow]

Your assumptions about the 40110 are correct. I know data sheets can be intimidating, but you should try looking at the one for the 40110. It can answer all your questions about how the chip operates and shows how to connect several in series.

P.S. Do you need the display to stop at 000 or 999 even if you get more counts? For that you will need some additional circuitry using the Borrow and Carry outputs, which I can explain if you like. If you don't do anything then the counter will underflow/overflow, and count down from 000 to 999, 998, etc. or up from 999 to 000, 001, etc.

 

[Wokyerdog]

ok, i couldnt obtain the 4011 and 4013 to decode the rotary so to pulse the 40110 i used tactile switches (with pull down resistors). I hooked up all the appropriate leads the the correct spots for the 7 seg led display but the output on the display is incorrect....meaning that it isnt a number.

When i click the up and down buttons, i see patterns on the display and the patterns go in the same order as i ascend and descend using the buttons so i know the chip is doing what it's supposed to. As far as i knwo the led display is a standard display. Am i doing something wrong?


-tim
I'd post a circuit if i knew how to, lol

 

[ericgibbs]

ok, i couldnt obtain the 4011 and 4013 to decode the rotary so to pulse the 40110 i used tactile switches (with pull down resistors). I hooked up all the appropriate leads the the correct spots for the 7 seg led display but the output on the display is incorrect....meaning that it isnt a number.

When i click the up and down buttons, i see patterns on the display and the patterns go in the same order as i ascend and descend using the buttons so i know the chip is doing what it's supposed to. As far as i knwo the led display is a standard display. Am i doing something wrong?

-tim
I'd post a circuit if i knew how to, lol

hi,
To post a circuit, use the Reply then Go Advanced button and then the Manage Attachments button, follow the instructions in the pop up window.

 

[crutschow]

It sounds like the LEDs are not properly connected to the 40110. Recheck the connections per the LED pinout diagram and the 40110 output connection diagram on the data sheet.

Edit: Is the LED common anode or common cathode?

 

[Wokyerdog]

I'd have to check once i get back to the lab.

but say it was a common cathode and i hooked it up liek a common anode, wouldnt that prevent it from working at all?


-tim

 

[crutschow]

......
but say it was a common cathode and i hooked it up liek a common anode, wouldnt that prevent it from working at all?

Yes. The circuit is designed to drive common cathode LEDs with the common grounded. But if you use a common anode LED with the common connected to V+, the display will not be correct.