Is PWM of OE pin on 74HC595 okay for LED brightness?

Started by dw in comp.arch.embedded13 years ago 2 replies

First off... I'm a PIC and electronics novice. I am breadboarding a cicuit to control LEDs using IO expansion. I am using the serial in -...

First off... I'm a PIC and electronics novice. I am breadboarding a cicuit to control LEDs using IO expansion. I am using the serial in - parallel out double-buffered 74HC595 shift register to control the LEDs. The shift register is controlled by a PIC 18F452. I created a PIC program to control the LED patterns. Now, I want to control the brightness of the LEDs. I tried using the...


74HC164 to drive a LCD panel

Started by sonos in comp.arch.embedded12 years ago 6 replies

Does anyone have suggestions/experience with using an 8-bit serial-in, parallel-out shift register like the 74HC164 to drive a LCD panel? I...

Does anyone have suggestions/experience with using an 8-bit serial-in, parallel-out shift register like the 74HC164 to drive a LCD panel? I have been using a LCD module in 4bit mode, and want to try something a little cheaper. How about hints for using 2 of these in tandem for a 2 digit LCD? 3 in tandem for 3 digit?... It would be useful to know how to use a SPI port on a tiny AVR w/ the...


Shift register chip to drive 7 Segment LED

Started by Richard in comp.arch.embedded12 years ago 6 replies

Hi I would like to drive a 7 segment using a shift register and have tried 74LS164 but it could not source enough current. Can anyone recomend...

Hi I would like to drive a 7 segment using a shift register and have tried 74LS164 but it could not source enough current. Can anyone recomend me some parts that can drive the 7 segment using serial. I have quite a few common cathode and anode LEDs and I would like to make used of them. Thanks Richard


Just one pin to control a shift register

Started by in comp.arch.embedded10 years ago 8 replies

I'm just a novice really in embedded systems, and I'm doing a college project. I've already gotten my board made and already stuffed it...

I'm just a novice really in embedded systems, and I'm doing a college project. I've already gotten my board made and already stuffed it with components, so the time for backtracking the design has been and gone. My design might not be brilliant, but I hope it will work in the end. Here goes... I have an 8-Bit shift register chip, and at any time there will only be one HIGH on it. For ins...


Single pin to control a shift register

Started by in comp.arch.embedded10 years ago 1 reply

(I already posted this but it didn't show up after half an hour so I posted it again. If there's a duplicate thread, then please ignore THIS...

(I already posted this but it didn't show up after half an hour so I posted it again. If there's a duplicate thread, then please ignore THIS one and put all replies in the other thread.) I'm just a novice really in embedded systems, and I'm doing a college project. I've already gotten my board made and already stuffed it with components, so the time for backtracking the design has been an...


Connect4: It all works perfectly

Started by in comp.arch.embedded9 years ago 1 reply

You may recall I've posted here in the last couple of months about my college project, which was to make a Connect4 game using 42 LED's, doing...

You may recall I've posted here in the last couple of months about my college project, which was to make a Connect4 game using 42 LED's, doing display multiplexing so that only one column is lit at a time. I had a very funky shift-register setup in which I used two precisely- timed RC circuits so that I'd only need one microcontroller pin to control the shifting. The theory was sound, but...


Inputs left floating at the very start

Started by in comp.arch.embedded9 years ago 23 replies

In college, I was always told not to leave input pins floating on a device such as a 74HCT chip. I was told that the device might...

In college, I was always told not to leave input pins floating on a device such as a 74HCT chip. I was told that the device might behave erratically if any of its inputs are floating. I have the PIC16F684. One of its inputs goes to the data input of a shift register, and the other goes to the clock input of the same shift register. On the shift regsiter, there's an RC circuit on the ma...


Simple Clockable Decoder Chip

Started by in comp.arch.embedded9 years ago 34 replies

Let's say we have an 8-Bit shift register. We reset it so that its outputs are as follows: 00000000 We then set the data input high...

Let's say we have an 8-Bit shift register. We reset it so that its outputs are as follows: 00000000 We then set the data input high and clock it: 10000000 We then drop the data input low and continuously clock it: 01000000 00100000 00010000 00001000 00000100 00000010 00000001 This is done easily using two pins from a microcontroller, o...


Just assume that it's not in a defined state?

Started by in comp.arch.embedded9 years ago 14 replies

You know chips like the 164 shift register, well I've been reading over the data sheet and it doesn't mention anything about the "boot up"...

You know chips like the 164 shift register, well I've been reading over the data sheet and it doesn't mention anything about the "boot up" state of the device. That is to say, if I have the master-reset tied high (it's active low), then what happens when I apply power? Will it start off all zeroes, or will it be in an indeterminate state? Similary I'm trying to find this information for...


Loss of synchronisation: Are the chips reliable?

Started by in comp.arch.embedded9 years ago 18 replies

A lot of you are familiar with the method of using a shift register to multiplex a matrix of LED's. My college project this year was to make...

A lot of you are familiar with the method of using a shift register to multiplex a matrix of LED's. My college project this year was to make a Connect4 game consisting of a 7x6 matrix of LED's. I had two choices for implementing the display: 1) Use two pins from the microcontroller 2) Use one pin from the microcontroller The technique of using two pins would be something like ...


Can distributed RAM on Xilinx FPGA be modified by onchip processor at run time and can output of the same connected to shift register in CLB.

Started by iwgauba in comp.arch.embedded8 years ago 1 reply

Hi, I am newbie in FPGA field. I am trying to implement look up table based logic on Xilinx FPGA. I want to implement the look up table in ...

Hi, I am newbie in FPGA field. I am trying to implement look up table based logic on Xilinx FPGA. I want to implement the look up table in distributed RAM and to connect the output of RAM to implement the logic in LUT. And to get reconfigurability modify the RAM content at run time by soft core processor on the same chip. Can anybody let me know if it is feasible or not. Thanks, Indra ...


Philosophical placement of counter in vhdl

Started by apalopohapa in comp.arch.embedded8 years ago

Hello. I normally have the control description (normally a fsm) separate from the datapath. Supposing I need a counter to time the duration...

Hello. I normally have the control description (normally a fsm) separate from the datapath. Supposing I need a counter to time the duration of some of the control outputs, for example, enable a shift register for 1000 cycles before doing anything else, would you instantiate the counter inside or outside of the fsm architecture? --------------------------------------- ...


Looking for 1.8V shift register

Started by Allan Herriman in comp.arch.embedded5 years ago 4 replies

Hi, I'm looking for a shift register to do some output expansion to drive LEDs, small relays, etc. I'd like to use something akin to the...

Hi, I'm looking for a shift register to do some output expansion to drive LEDs, small relays, etc. I'd like to use something akin to the 74xx595 which has a serial input and 8 outputs. Good so far. I need to use a shift register with either open drain outputs, or outputs that can drive at least 3.3V (high or low, I don't mind). The current will be up to a few tens of mA. I do...