PID is implemented when a precise way is needed to drive an external device that provides feedback. Heaters with temperature sensors, and servo motors are examples where PID is used.
This app note by Microchip gives instructions how to implement PID control in PIC18 projects. Basic terms are explained inside the document as well as algorithm flow charts to understand how PID is implemented. Microchip has also provided assembler source code to go with this app note.
Most logic ICs require fast transitions between levels to function properly, while the switch is being made the IC draws additional current, and if it is kept in this intermediate state failure of the chip is possible.
This app note explains how Shmitt triggers are used in circuits that require slow changing signals to drive logic ICs.
Schmitt triggers should be used anytime you need to translate a sign wave into a square wave…
Or they should be used where a slow or noisy input needs to be sped up or cleaned up as in the switch de-bouncer circuit.
Schazamp tried to read an I2C temperature sensor using only logic chips. It isn’t working yet, but the writeup is impressively detailed:
My project is to use logic devices to read a TC74 temperature sensor. The general idea is to have some kind of master clock (from 3 of the 74HC04’s 6 inverters), manipulate the clock to drive the SDA and SCL lines, and then clock data from a sequence of PISO shift registers (75HC165) to drive the I2C bus commands (start, device ID, write, set read address, start, device ID, read) and then, based on a series of counters, clock the response from the device off the I2C bus into a SIPO register (74HC595), and use that to drive some 74HC4511s and 7-segment displays.
Via the forum.
Three terminal voltage regulators like the lm317 are common and easy to use, for most applications only two additional resistors are needed to get a stable power supply. This app note by Linear Technology provides guidelines how to increase the performance of these devices.
Current output could be increased from a few amps to tens of amps, by adding an external transistor. The article covers how to build this circuit without sacrificing output regulation, and adding thermal shut-down to the output transistor in case of a prolonged short circuit.
Power dissipation could be decreased by adding a switching dc/dc converter before the three terminal regulator. By using an op amp to drive the switching regulator, it keeps the input voltage level at a constant difference above the adjustable output level.
The article also provides a example circuit how to use a three terminal voltage regulator to regulate very high voltages of a few thousand volts.
Steve Schuler likes to hack the Spy Video Trakr. His most recent efforts involve adding a Lego grabber arm. He writes:
I have added a Lego grabber arm to the Spy Video Trakr. The Trakr is a remote controlled robot equipped with a microphone and color video camera, speaker, a near infrared LED for night vision, an SD memory card slot for recording audio/video and 8MB of on board memory for storing downloadable and user designed programs. The remote control unit has control levers to drive the robot, a speaker and color video display so you can hear the audio picked up by the microphone and display the video transmitted by the camera, and several function buttons that can be used to control additional program functions of user designed programs.
You can read about this and Steve’s other Trakr hacks at his website.
We just wonder what would happen if the Trakr/grabber tabbed the tabby in the video’s background…
Via the contact form.
Jonathan entered a Flickering Jack-o’-lantern for the Open 7400 Logic Competition. He recorded a video of his project, which is available below.
I used a 74HC14 to create four different square waves of different non-harmonic frequencies that were mixed together to flicker a red and blue LED.
Via the contact form.
Continue reading “7400 competition entry: Flickering Jack-o’-lantern”
Embeddederic entered a 7400 series logic PLL-based switch-mode power supply into the Open 7400 Logic Competition.
Via the forum.
Facebook free PCB Friday is on the way. Don’t forget to share your current project in the comments or the forum.
Here’s a summary of major developments over the last week:
Coming this week:
What are you hacking this week?
Jason added another entry to the Open 7400 Logic Competition:
80M direct conversion receiver
I had fun using the 74HCU04 to make a little TRF AM radio, but my original goal was to build a direct conversion receiver. I didn’t think I would have time before the deadline, but I managed to squeeze it in with less than an hour to spare!
Via the forum.
Andrey entered a Game of Life build from CMOS logic into the Open 7400 Logic Competition:
This was supposed to be my entry for Open 7400 logic competition. It’s Conway Game of Life on 8×8 LED dot matrix, made with almost only 74HC and 4000/4500 series of CMOS logic chips.
Via the contact form.
Arup entered his Homemade 7400 into the Open 7400 Logic Competition. A video of it proving his concept is available below.
At an earlier post I’ve said that I didn’t have 7400ICs in my drawer.
Surprisingly, the local store was saying 74HC00 out of stock. Hence I decided to make my own 7400 IC.
7400 is a quad two input NAND gate.
Any digital circuit can be made with universal gates like NAND or NOR, even some pretty analog circuits can be made using these as the competition entries show.
Via the forum.
Shaos entered a (balanced) ternary electronic device based on the 74HC4052 into the Open 7400 Logic Competition. Ternary Balanced ternary is a base-3 number system, instead of bits (0, 1, 10, 11, etc), this counts in trits (-1, 0, 1):
The “Test bed” consists of 20 sockets for testing “our standard ternary components“. For ternary full adder only 7 sockets are used…
+5 volts is positive ternary value (P) – GREEN LED, 0 volts is zero ternary value (O) – OFF LED, -5 volts is negative ternary value (N) – RED LED
Via the forum.
Check out the video after the break. Continue reading “7400 competition entry: Ternary base-3 electronics using 74HC4052”
Kevin entered a Detailed consumer IR capture with 74HCxx series chips for the Open 7400 Logic Competition:
This is a CIR (Consumer IR / Remote Control) capture device built with 74HCxx series logic chips. It allows a computer to do a detailed capture with carrier frequency, on/off durations, and on duration pulse counts.
Via the contact form.
Helmy entered an 8-Channel 6MS/s USB logic analyzer into the Open 7400 Logic Competition. His device converts the 8 channel parallel inputs into a UART based serial signal. It outputs this serial signal to the input pin of a PL2303 USB-to-Serial chip which sends the data to the computer.
Via the forum.
Matt built a fully featured Drum machine for the Open 7400 Logic Competition. Check out the video of its operation and his sound generating skills below.
This is a four-channel, sixteen-step percussion synthesizer/sequencer created entirely from discrete logic chips (mostly 74HC-series parts). That’s right, no microcontroller or software of any sort. It was created for the Dangerous Prototypes 7400 Contest in a little over one month of spare-time work.
Via the contact form.
Continue reading “7400 competition entry: Discrete Logic Drum machine”
Joe entered his Horologium Romanum into the Open 7400 Logic Competition. It is a clock that displays it’s time in Roman numerals built from logic ICs. There is a video of it below.
Despite the Roman Empire’s sanitation, medicine, education, wine, public order, irrigation, roads, fresh-water system, and public health: they never had a decent digital clock. Well here it is!
Via the contact form.
Continue reading “7400 competition entry: Horologium Romanum”
Luc entered his Wheely bin night reminder into the Open 7400 Logic Competition:
Because the competition was so open ended in its brief, I placed two constraints on myself:
First, I had to make do with the logic chips (and other components) I had on hand. No going to Jaycar or placing an order through Element 14; only junkbox parts allowed. I had more 4000-series parts than 7400-series parts, so the design is based on 4000 CMOS logic. Because of this constraint, it is sub-optimal in many ways – requiring more parts than had I had access to the more highly integrated CMOS parts.
Second, I had to make something that solved a problem I faced. I always forget to take the bins out on bin night. What I needed was a system of reminders. Sure, I could have set an alarm on my phone. But what would be the fun in that. So I set about designing the logic system required to remind me that:
- The Red (garbage) and Yellow (recycling) wheely bins go out weekly on a Monday night.
- The Green (green waste) wheely bin goes out on a Tuesday night on alternate weeks.
Via the contact form.
After being discouraged by a failed order for their initial entry, Ben and his girlfriend decided to enter a somewhat different design into the Open 7400 Logic Competition. It consists of taking their anger out on 7400 chip. By pumping 1 Amp of current at 12V into the IC, they turned it into a heater, and a firecracker a few minutes later. Check it out in a video below.
Via the contact form.
If your Arduino project has minimal IO needs, you may want to consider shrinkifying it. This video demonstrates High Low Tech’s method for programming an ATTiny with Arduino code. Maker Randy Sarafan has designed an 8-pin Arduino programming shield to make the task easier.
Via Make.
Daniel entered an Electronic realization of Etch-A-Sketch toy into the Open 7400 Logic Competition:
This project is an electronic realization of the famous Ohio Arts “Etch-A-Sketch” toy, with a twist. Like the original, two rotary knobs are used to move a cursor horizontally and vertically, respectively, but unlike the original, a third knob selects one of 32 different sketch pages. Simple flip-pad animations can therefore be created by twirling the page knob rapidly.
Via the contact form.
