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33 Threads found on Latch Led
Hi, This solution doesn't use a PIR, but I can't think of any solution for what you describe... If the room only has one entry point, maybe an ir led across the doorframe could be used to latch on for entry and off for exit from the room.
But you're supposed to write to the output latch register; the PORT register is for reading. Yes, you should do so, at least for clarity. But according to PIC18 reference, writes to PORTA and LATA go both to the output latch. You also see that analog configuration only affects PORT input operation. So it's more likely a problem of
Parallel port has >50kB/s bandwidth easily. Your design requires a refresh rate spec and allowed latency, supply power source and led Vf @If specs. If 0.5ms is allowed then refresh rate is 2kHz then parallel rate is 25kHz x8bit / Serial encoder/decoder would require 100 x 2kHz rate. If you need to latch the led state, a serial clock and (...)
A CMOS latch springs to mind off the Rx data.
I do not know for RGB model, but for single color 16 x 32 dot chinese led modul there is 16 pcs of 74hc595 (1/4 refresh). Each panel have 74hc245 buffer on data, clk, latch and enable line. There is one NOT gate, i think on enable line, hc138 decoder and 8 pcs dual p-channel fet transistors in SOP8 package for driving rows
Hi there. I'm quite a newbye in this field, but I'd like to show you my ideas and possibly discuss how to improve them. In my current project I need to create a little led stick of 16 led with a simple interface so that any mcu may control it. In essence, I have 4 pin to address a single led , an analog pin and an enable digital signal. (...)
Electric Fields are inherently high impedance and impulse EMF are exceptional wide bandwidth. What range of levels and frequency are you hoping to detect in uV and Hz? A cheap FET gives the impedance required but further signal amplification is required to trigger a latch such as a small signal SCR to turn off an led driver, thus at least 3 o
I can see from the datasheet that this is a shift register so the fundamental question I have is are you latching the output? You are seeing the data out so when know that you are shifting it in but I am not sure that you are latching it when it has all been shifted in place.
Hello djc, submit the schematic for a clear understanding of the connection. from your description it seems that you are getting continuous input, so the led turns ON and OFF continuously. may be you have to change the HW logic to configure the latch so that it will give the input only once Regards
Hi.... I am trying to control an led matrix(5X7) using an 74HC595 latch+shift registers and atmega32. I checked out several codes on the was quite easy. So i tried making up my own code using atmel studio. But the output pins show zero output whatever serial data i send. (The multimeter showed zero volts with GND as reference)
Hello, I have to interface around 120 led's to PIC18F4520. I am planning to do it with latch IC 74HCT574. But it increases number of latch IC's. As per the datasheet the maximum current sourced and sunk by all ports of micro controller is 200mA. Is it enough to drive all the led's? Please suggest. Thanks, paddy
Looking at the timing timing diagram and the truth table, the old bits will not remain their. Moreover you can see that the ic uses SPI interface so it has got SDO, where one bit enters the shift register then the other end bit is shifted out on SDO which means that the old bits will not remain their. whenever the LE goes low the input data bits
I'm trying to use my wireless doorbell to switch off my water pump. The problem is how to use the receiver signal to latch a relay. Search the net but no clear solution found ! I've driven led from a speaker wire with transistor (doorbell receiver circuit) but don't know how to use this signal to latch a relay. I'm planning to use 6v (...)
You have generated many latches in this design, by incompletely specifying the state of several registers. Registers such as led and solenoid are not initialized, and are described in only a few states. This incomplete specification leads to generation of latches, which undesireable for most designs. Hence the warning regarding (...)
there are two approaches. one is to latch each led state with a pile of latches to drive 8digits by 7 seg. or use MUX approach and use a PLD or a couple drivers to scan each digit. You might be able to drive it directly with CY74FCT138T 64mA current sink and 1 of 8
Dear All, I have 4 shift registers for 32 columns and 8 rows are directly connected via Port A of Microcontroller. I have to activate each row one by one and feed all the 32 columns data and then latch them. The problem is: 1) how to send 32 bits for 32 columns one bye one, and 2) How to create scrolling effect from right to left...? e.g.
Thanks a lot, I will check the enable and latch carefully.
Hi. How are you going to read the data into the latch. One row at a time, or just having some external hardware/circuitry that is synced to the counter?
Posted in error! - Sorry :)
Circuit to count led pulses and latch on right number Should be quite simple.... I think...? Say cct 'sees' 24 blinks - then no more (ie, too many means no_good) I'd prefer it f this can be done without a microcontroller - ie. a simple fixed cct (no need to be able change the correct count once built). If the right number - then (...)
good day EDA fellows.. I had this one question.. I am doing a charge pump for the led. I have two powerPMOS. How can I check any forward bias junctions in the circuit? Something any relation with latch-up. Can I obtain these information in the .lis file? Thank you for anyone who can share his ideas and experience.
Both options have advantages and disadvantages. In parallel connection (without latch IC): you will save the hardware but the programming will be little bit complex, as you need to refresh each display faster so as to avoid flickering In serial connection (using latch ICs): hardware will increase programming will be easier, as you need t
Every logic family is characterized by different output drive current .. For example, 74ACT logic family can drive +/- 24mA of IOH and IOL .. Any output current above ≈5mA can directly drive an led (via a resistor) .. You have to google for I of your latch .. Rgds, IanP :D
Hi, I'm designing a led matrix for Outdoor VMS of a considerable size (about 5meters). There are about 16 matrix. From matrix to matrix are traveling signals, like clock, data out, latch enable etc. What is the best circuit to amplify / regenerate signals? And about noise filtering (I did see (in a commercial product) some inductors in seri
better way is to use latch and no multiplaxing. directly use latch and use mcu behind it
a) are the above signals(just interfacing) enough(optimized) for the subjected application except VDD and GND. - You need to drive RCLK (Register clock) pin as well to transfer content of shift register to output latch. You need rising edge to do that. b) Is there any requirement for RCK clock pin?? -look under a c) how should i conne
hi I'm working on TMS320F2812, a 32-bit DSP. I need to interface an a 8X1 led with my Processor through the GPIO's of the processor. The GPIO's are connected to the led's through a 74HC273 D-latch. Can anyone give me pointers on how I must go about the same ?? I have a couple of doubts : 1. My GPIO pins are wired to the D0 to D7 (...)
Hello, I am newbie to FPGA an have question. I try to make 16 bit bidirectional data port so I can write value to 16 bit latch to turn on led's and read input switch back to microcontroller, also 16 bit memory map port to micro. When I use Quartus functional simulator I see that led port is write correctly but later in simuation the (...)
I'm trying to run a matrix of 16x5 of regular red led's using the TLC5920 and I was wondering if anyone had a sample working schematic that I could use as a reference. I downloaded the pdf but it was sparse on details for how exactly to set it up. I'm using a PIC18F2420 to run it and have spi(in,out,clk), latch, blank, csel(0-2), and +5V and GND
You can use this latch IC 74HC273. It has 8 D-FlipFlops.
Hai, everyone i try to drive the port 82C55 via pararel port, but ihave problem with latch that mention on schematics, i attach all port 8255 wih sourcing led and i inisialize the port tobe output. when i running program the problem arise 1. led on port A that should ligh on it's following this condition off-on-off again (some kind this (...)
heh ppl, am assigned this project that has this user using dip=switch input a 4-bit binary into this 'game'. this is to be compared to another dip-switch's value. 4 wrongs and a red led will light. its its right in >4 tries, green led lights. and a d-latch pushbutton for user to 'send' input. am using a 4-bit comparator 74'85 and [
Was just thinking... Is it not possible to cascade shift registers with a clock and data line... And then use 1 enable line to latch the clocked data to the output. In this way you can have as many outputs as you like on 3 pins. Number of outputs are the number of clock cycles. Think I will try this also...