A data logger is a device that records measurements over time. The measurements could be any physical variable like temperature, pressure, voltage, humidity, etc. This project describes how to build a mini logger that records surrounding temperature values. This is the figure of the circuit; Temperature will be measured with a DS1820 temperature sensor. DS1820 is a one wire digital temperature sensor from Dallas Semiconductor (now MAXIM). The operating temperature range of the device is -55°C to +125°C with an accuracy of ±0.5°C over the range of -10°C to +85°C. The temperature sensor output is 9?bit Celsius temperature measurement, and so the temperature resolution corresponds to the least significant bit, and which is 0.5°C. But in this project we will use only the most significant eight bits. Therefore, the temperature resolution will be 1°C. The measured temperatures will be recorded into the internal EEPROM memory of PIC12F683.
The first location of the internal EEPROM will store the sampling interval of data logger. Sampling interval defines the time gap between two successive measurements. This project will have 3 options for sampling time: 1 sec, 1 min, and 10 min. These are user selectable. The second location of EEPROM will store the number of measurements recorded so far. And the remaining 254 EEPROM locations will store 8?bit temperatures. So, using 10 min sampling interval, 254 bytes of EEPROM will provide data logging for 42 hours. The recorded measurements can be sent to PC at any time through a serial link at 9600 baud.
Here’s a design circuit for simple circuit controls a popular 2-line x 16-character LCD by a PC via printer port. It doesn't use the Bi-directional feature found on newer printer ports, thus it should work with most, if not all Parallel Ports. These LCD Modules are very common these days, and are quite simple to work with, as all the logic required to run them is on board. This is the figure of the circuit;
The LCD panel's Enable and Register Select is connected to the Control Port. The Control Port is an open collector/open drain output. While most Parallel Ports have internal pull-up resistors, there are a few which don't. Therefore by incorporating the two 10K external pull up resistors, the circuit is more portable for a wider range of computers, some of which may have no internal pull up resistors. The 10k Potentiometer controls the contrast of the LCD panel. The software source code has been written in Borland C++.
Here’s a design circuit for a MIDI interface between drum pads and computer or hardware sequencer. Using this circuit you can hit pads with drumsticks and store the MIDI data in real time. This is the figure of the circuit;
This circuit is based around the PIC16C84 microcontroller which scans the inputs on RB0 to RB7 and when a high is detected the software transmits the equivalent note-on (and then the MIDI note-off after a short delay) for the required drum sound on the MIDI output on RA0.
This is a design circuit for digital light sensor circuit using microcontroller. The ISL29001 is an integrated ambient light sensor with ADC and I2C interface. With a spectral sensitivity curve matched to that of the human eye, the ISL29001 provides 15-bit effective resolution while rejecting 50Hz and 60Hz flicker caused by artificial light sources. This is the figure of the circuit;
In normal operation, the ISL29001 consumes less than 300µA of supply current. A software power-down mode controlled via the I2C interface disables all but the I2C interface. A power-down pin is also provided, which reduces power consumption to less than 1µA. The ISL29001 includes an internal oscillator, which provides 100ms automatic integration periods, or can be externally timed by I2C commands. Both the internal timing and the illuminance resolution can be adjusted with an external resistor.
For a better understanding of how to specify device settings when using both analog and digital signals, this section uses the I/O board DAS-1601 from Keithley-Metrabyte as an example. The following is a specification summary of the DAS-1601 board:
Analog input (A/D) -- 16 single-ended or 8 differential analog inputs (12-bit), polarity is switch configured as either unipolar (0 to 10 volts) or bipolar(+/- 10 volts). Gain is software configured to 1, 10, 100, and 500.
Digital input -- Four unidirectional digital inputs Analog output (D/A) -- Two
analog outputs (12-bit). Gain is switch configured as 0 to 5 volts, 0 to 10 volts, +/- 5 volts, or +/- 10 volts
Digital output -- Four unidirectional digital outputs
Base address -- Switch configured base address
This section explores different configurations for input signals. Once an Analog Input block has been placed in the model and the I/O board selected and configured, you can set up the Analog Input block to handle input signals. Single analog input -- The most basic case is for a single analog input signal that will be physically connected to the first analog input channel on the board. In the Block Parameter: Analog Input dialog box, and the Input channels box, enter 1 or [1]
The use of brackets is optional for a single input. Input vector with differential analog -- Analog channels are numbered starting with channel 1 and continue until you reach a number corresponding to the maximum number of analog signals supported by the I/O board. In the case of the DAS-1601, when configured as differential inputs, eight analog channels are supported. The analog input lines are numbered 1 through 8. The complete input vector is
[1 2 3 4 5 6 7 8] or [1:8]
If you wanted to use the first four differential analog channels, enter [1 2 3 4] Input vector with single-ended analog -- Now, assume your DAS-1601 board is configured to be single-ended analog input. In this case, 16 analog input channels are supported. The complete input vector is [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16] or [1:16] To use the first four single-ended analog input channels, enter [1 2 3 4] or [1:4]
The Industrologic IR232 is an infrared to RS-232 converter that is based on the 12 bit Sony SIRCS protocol. In addition to being able to send and receive control codes to and from the infrared and RS-232 ports, it can also be configured to send specific character strings to the serial port when selected infrared codes are received. This will allow it to act as a host and controlling device to any slave device that can accept RS-232 commands.
On-board 40 KHZ infrared receiver module and 940nM high-power infrared LED Visible LED to confirm reception of infrared transmissions
EEPROM for storage of configuration information and character strings Multiple modes of operation available-
- Send programmed messages when specified infrared codes are received
- One and two byte binary transmission and reception
Serial port with true RS-232 interface and DB9F connector matching PC compatibles
Selectable baud rates up to 19200 baud
Pin-type power jack for easy connection to wall block power supply
On-board +5 volt power supply with +5 volt output available on DB9 for auxiliary devices
Includes all items needed for immediate use: Wall block power supply, RS-232 cable for connection to PC compatibles during setup, and terminal emulation software for PC compatibles.
LED ball physically assembled in a matrix of dimension 20 Rays and 7 LEDs. LEDs are governed microcontroller and two decoder K155ID10. Operating current 80mA decoders, this is enough to connect the LED matrix in the dynamics of directly between the microcontroller and decoders, excluding transistors, the brightness of LEDs is sufficient. The control circuit assembled on two boards, located in the center of the ball, moving away from them rays – soldered in one line cathodes, LEDs, and the anodes are connected by layers of thin wire as a cobweb. This is the figure of the circuit;
Before installing the need to bend legs of chips at 90 degrees, solder all the details of one party to the first charge, then at the opposite conclusions to put a second charge and finish soldering. Podpayat supply wires and programming, flash microcontroller and check the output signals. Only then can continue mounting LEDs. To facilitate the work necessary to prepare a template – a hole in the cardboard (plywood, plastic) 7 holes for the LEDs on the same line two centimeters. Then bend cathodes of LEDs 90 degrees right next to their body, insert the LEDs into the template and unsolder beam deflected conclusions. Each of the 20 rays soldered into the board and turn down under the picture. To give the rigidity of the whole structure, anodes maximum distance from the center LED solder together a 10-centimeter segments of tinned copper wire, giving the correct type of construction of the dodecahedron (face-pentagon at each vertex, three edges). Then solder each layer remaining anodes of LEDs and connect each layer to the relevant conclusions resistance. With proper installation will start building a microcontroller embedded in his light effects. For a change, it automatically changes the number of repetitions, speed, brute force effects. This is enough to exclude the interference of the operator. The program is written in a medium BASCOMAVR, if desired in the source code can add or change inherent effects.
This is a project that is a short range, infrared and ultrasonic scanner that uses a standard hobby servo to move the sensors and a color LCD screen to display the information from the distance sensors. The information displayed on the LCD is an overhead view of the scanning area, with increments of distance from the distance sensors. This is the figure of the project;
The core of the project is the ATMEGA32 microcontroller from Atmel. It controls the servo, gathers information from the sensors and places the information on the LCD screen. There is 32K of flash in the microcontroller and the software uses about 13K of that. Since the LCD uses a maximum of 3.3V, the microcontroller is run at 3.3V.
This is a design circuit that is simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily. This is the figure of the circuit;
All pulses to be counted are to be TTL compatible. They should not exeed 5V and not fall below ground. You can add more digits by building a second (or third, or fourth, etc…) circuit and connecting the pin 11-6 junction of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in the other circuit. You can keep expanding this way to as many digits as you want.
This circuit is design circuit to build a digital compass that displays both the direction and cardinal points on a television. Other functionalities were added to complement the sensor interface, such as, temperature display, magnetic declination input and disability option. This is the figure of the circuit;
The HMC1052 two-axis magnetic sensor contains two Anisotropic Magneto-Resistive (AMR) sensor elements in a singleMSOP-10 package. Each element is a full wheat stone bridge sensor that varies the resistance of the bridge magneto resistors in proportion to the vector magnetic field component on its sensitive axis. The two bridges on the HMC1052 are orientated orthogonal to each other so that a two-dimensional representation of an magnetic field can be measured. The bridges have a common positive bridge power supply connection (Vb); and with all the bridge ground connections tied together, form the complete two-axis magnetic sensor. Each bridge has about an 1100-ohm load resistance, so each bridge will draw several milli-amperes of current from typical digital power supplies. The bridge output pins will present a differential output voltage in proportion to the exposed magnetic field strength and the amount of voltage supply across the bridge. Because the total earth’s magnetic field strength this very small (~0.6 gauss), each bridge’s vector component of the earth’s field will even be smaller and yield only a couple milli-volts with nominal bridge supply values. An instrumentation amplifier circuit; to interface with the differential bridge outputs, and to amplify the sensor signal by hundreds of times, will then follow each bridge voltage output.
Last week I wrote my 555 contest entry on 555-logic (and its 2-bit grey-code counter implementation as proof of concept) on this blog in a huge rush. As my wife was waiting for me to accompany her for some business, I had to finish up the 555 contest entry report which was due only a few hours before deadline (due to geographical location advantage, I get to sleep at midnight and rush afterwards, in the morning instead :D)
I started the idea to make 555-based digital logic circuits quite early when time was plenty before the 555 contest submission deadline. Another crazy idea in my mind was actually to make an Op Amp out of a 555. Last semester I taught analog electronics, and one of the lab experiment in the class was to actually build a self-made op amp with those very popular 9012s and 9013 BJTs in Indonesia. But it didn’t take long before I scrapped this idea, thinking it was kind of almost impossible, since not all comparator pins (it has this similar symbol with an op amp right?) inside the 555 could be accessed. I once read a PhD thesis that had this VCO-based op amp though, and I spent some time contemplating this concept. I even thought to make a 555-based filter.
This semester I get to teach digital designs with FPGA, and during early weeks of the class the idea of building basic logic gates with 555 came into my head. The solution on how to make it though, came real real late.
My early concept of 555 logic was a hope that a single 555 can be made into either a NAND gate or a NOR gate. The 555 as an inverter was already obvious. Only if I could make a NAND gate or a NOR gate, ANY logic gates can then be implementable (see articles on NAND logic or NOR logic in Wikipedia). I googled 555 nor gate but nothing relevant showed up that time (perhaps now there are three different styles of 555 nor gate out there, thanks to 555 contest ;D). I started by writing simple truth tables of a 555:
555 Truth Table
Reset(4)
Threshold (6)
Trigger(2)
Discharge(7)
Out(3)
0
0
0
Disconnected
0
0
0
1
Disconnected
0
0
1
0
Disconnected
0
0
1
1
Disconnected
0
1
0
0
Disconnected
1
1
0
1
No change
No change
1
1
0
Not allowed
Not allowed
1
1
1
0
0
Looking at the above truth table makes it real hard for me to find any useful logic functions other than the already-obvious inverter. Not to mention, there is this “not allowed” state and “no change” state that forces me to tie the threshold pin and trigger pin together to avoid the not allowed state. So, oh well, okay it felt hard to solve, so I might as well not think too much about it and think more about my work at the uni and my family instead.
Around 3 days before submission deadline I looked at the problem once more to find potential solutions. Had I been a better digital designer, I might have thought about the AND gate with the trigger-threshold pair pin as an inverting input (as pointed out by the Paleotechnologist). But apparently this did not seem apparent to me that time. Instead, as I dealt with transistors more than I deal with gate level designs, I saw a transistor with a free collector pin inside the 555 and thought that why not use this transistor as itself instead? (thereby wasting and throwing away the significance of some other parts of the 555) Transistors can be used as switches, and from the way the transistor is connected inside the 555, it became apparent to me that the transistor inside the 555 can indeed be used as a switch: we can give either a logical high voltage level or a low one to the gate of the transistor indirectly. Giving the correct threshold and trigger inputs will control the transistor’s gate as if we are controlling the transistor directly. The sketch below shows how this can be done:
Using the discharge transistor of a 555 as a general purpose pull-down switch
I normally teach my students on how to implement logic gates with either CMOS logic, or (bipolar) transistor-logic. For lab works, I preferred students make transistor-logic circuits, using NPN transistors as pull-down networks, mimicing NMOS-logic circuits. NMOS logic requires pull-up resistors. The NOR gate made with NPN transistors I had in mind looked something like this:
NPN transistor NOR gate
The 555 circuit has three 5k resistors connected in series, adding up to 15k, connecting the VCC pin to GND pin of a 555. There you go, a 555-based resistor! The pull-up resistor is quite large though, but I thought it wouldn’t be too much of a problem because the inputs of 555-logic gates are essentially input pins of comparators (with a notably high input impedance). My version of a 555-based pull-up resistor was like this: (uses pin Vcc and Gnd as resistor terminals)
Unusual use of a 555 as a resistor
This idea of making a NOR gate therefore requires three 555s for a single NOR gate. Two as transistors, one as a pull-up resistor. Though silly may it seem, it didn’t stop me from actually doing it: test the circuit on my project board. The resulting 555 implementation of a NOR gate with my above-mentioned approach is shown here:
Two 555s as pull-down transistor switches, one 555 as a pull-up resistor, forming a NOR gate
Photographs showing my early experiment of this 555-based NOR gate are shown below:
The DIP switch is set to give inputs "00". The two powered-on LEDs indicate the output pin (3) of each 555 are both ON, hence the inputs are indeed LOW. The output of the NOR gate is indicated by an LED connected between VCC and an R connected to the GND pin of the right-most 555 (the actual NOR gate output pin). It is currently OFF, indicating that the NOR gate output is HIGH. This gives a correct result as it should be. Inputs "00" gives output "1".
The DIP switch is now set to give inputs of "01". The output becomes "0", indicate by the lit LED (current passing through LED, from VCC to 0V of the NOR gate output).
Inputs "10" resulting in output "0".
Inputs "11" with "0" output. Again, this is correct as a NOR gate.
A NOR gate as itselfmay not mean too much. So I decided to think of any possible case study to show the power of this 555-based NOR gate. I need more than just a NOR gate. Digital circuits are either combinational circuits, or sequential systems. And true power of digital systems are in this sequential form, with clocks orchestrating their operation. To make sequential systems, we need memory, or flip-flops. Trying to make use of the internal 555 flip-flop, though seemed very attractive, was another headache that needs to be solved. It became a headache because I wanted the flip-flop to be edge-triggered, and I want the solution to use 555s only. The 555 flip-flop was an SR flip-flop with reset pin, but no clock or enable input. I opened up several textbooks in my posession and good solutions on how to make a flip-flop circuit clock enabled was shown in two of the textbooks I read: Digital Integrated Circuits by Rabaey and Practical Electronics for Inventors by Paul Scherz.
Making a normal D flip-flop to be high level-enabled requires addition of normally two AND gates. Both of these AND gates will require that another signal, the CLOCK signal, be HIGH, in order that any change to the flip-flop output can be made. When the CLOCK signal is LOW, the flip-flop will only see zero inputs on both input terminals, therefore the current state of outputs will be retained.
But the internal circuit of the 555 is unique! Activation of the R and S input of the internal 555 flip-flop requires the opposite logic value of the trigger and threshold input pins of the 555. So unlike a normal SR flip-flop that requires a "00" input for "no change", our 555 will need a "01" input (on the threshold and trigger input pins) to make the internal SR flip-flop do the same "no change" thing. After some contemplation, the solution I came up with looks something like this:
Making the 555 as a D flip-flop with clock input (high-level active). The 555 will need an AND gate and an OR gate with one input bubble. The AND gate and OR gate could be made with NOR gates, right?
The AND gate and OR gate (with one bubble input) MUST be made with 555s too for consistency. All ICs in this project are 555-based. To do so, we should transform the above circuit into an equivalent circuit based on NOR and NOT gates. NOT gates can be made simply by connecting the threshold and trigger pins together, forming the input of the inverter. The output of the inverter is also the output pin of the 555, like the sketch below:
To implement the AND and OR gate circuitry mentioned above (for the 555 D flip-flop) using only 555s, we need to build a NOR and NOT-based circuit like this:
Equivalent circuit of AND and OR gate (with one input bubble) using NOR and NOT gates. NOR and NOT gates will then be implemented using 555s. Therefore this circuit will require 2x3 555s (as NOR gates) and 3x1 555s (as inverters). Total: 9.
The above solution still needs something more: we need to make the D flip-flop (DFF) edge-triggered instead of level-enabled. One way to do this is to make a master-slave arrangement, using two clock-enabled D flip-flops. If this was to be made entirely with 555s, then it will need one 555 for the SR flip-flop, nine for the clock-enabling thing, and double that for a pair of the same DFF. This gives an astonishing amount of 20 555s, plus one more to invert the clock on one of the DFF. Twenty one 555s is not a small amount of ICs just for a single edge-triggered flip-flop able to keep 1-bit of information only. So I opted to the alternative solution, which was to build a pulse-forming circuit prior to the level-enabled DFF which will turn a clock edge into a very short pulse, like the circuit here (which uses a NOR and an inverter so that it can be built with 555s):
Short pulse generation from a negative clock edge using a NOR gate (three 555s) and an inverter (one 555). This circuit therefore requires four 555s.
With this approach, an edge-triggered DFF will need 10+4 or 14 555s. Alternatively, we can use four 556s and six 555s. Single 555s are still necessary in this approach because on our NOR gates, we use one 555 as a resistor with an unordinary use of its ground pin. Fourteen is still a lot, but compared to 20, it's a bit better. Images showing the built DFF can be seen here:
The resulting edge-triggered DFF with the above solution is a negative edge-triggered DFF, with an asynchronous RESET pin (using the RESET pin of the 555). I did not show this in my schematics nor videos, but it is actually built and tested on the 2-bit grey-code counter discussed on my previous post. You can try to zoom the following image of it, where I put a reset button near the LED of Q1. This reset button pulls the reset pin of all 555 DFFs to zero. It worked, but I have no photos or videos yet to show.
2-bit synchronous grey-code counter as proof of concept of proposed 555-logic. It works! :D
A video clip showing my experiment proving that the individual DFF works (as an edge-triggered one) is shown here:
To prove that the 555-logic concept I proposed does really work in a (bit) usefull application, I built a synchronous 2-bit grey code counter implemented entirely in 555-logic. A 555 clock generator was used too, resulting in an equivalent total of 30 555s, already shown above.
This Switch On Time Delaycircuit has been designed to create a lamp switch operatedelectronically with an option of setting a delay in the time ofexecution of operation to reduce one or more lamps in a stairwell orany other places where this circuit may be useful. The circuit can beuseful to control various lamp or appliances that can be connected inrelay contacts.
The circuit that takes advantage of the emitter/base breakdown voltageof an ordinary bi-polar transistor. The reverse connected emitter/basejunction of a 2N3904 transistor is used as an 8 volt zener diode whichcreates a higher turn-on voltage for the Darlington connectedtransistor pair. Most any bi-polar transistor may be used, but thezener voltage will vary from about 6 to 9 volts depending on theparticular transistor used. Time delay is roughly 7 seconds using a 47Kresistor and 100uF capacitor and can be reduced by reducing the R or Cvalues. Longer delays can be obtained with a larger capacitor, thetiming resistor probably shouldn't be increased past 47K. This SwitchOn Time Delay circuit should work with most any 12 volt DC relay thathas a coil resistance of 75 ohms or more. The 10K resistor connectedacross the supply provides a discharge path for the capacitor whenpower is turned off and is not needed if the power supply already has ableeder resistor.
The basic idea of 555-logic is to implement digital logic circuits with 555 ICs only. This gives advantage that a relatively higher and wide range of power supply voltage can be used, limited by the specification of the 555 IC (4.5V - 16V). According to Shannon through his famous 1937 Masters thesis at MIT, any combinational logic circuits can be made with switches. With semiconductor technology, these switches can be in the form of transistors. To use 555 as a transistor switch, one can utilize the internal pull-down transistor of a 555 (Figure 1).
Figure 1 Using the transistor of a 555
There is a restriction on how to use this transistor as its emitter is connected to ground pin (4). Even though one may be tempted to connect that emitter (or ground pin) to something other than ground voltage, this will not guarantee to work since the ground voltage is needed by other parts of the 555 IC to function. Therefore, the use of the 555 transistor as a switch is restricted to the implementation of pull-down network of switches with no cascading of emitters to collector of another transistor. This leaves a reasonable choice to implement a NOR gate. A NOR gate can be made with two pull-down transistors with collector pins connected together forming the output. A pull up resistor is to be connected between these collector pins and VCC, and a 555 can be used for this since a series of three 5ks resistors exist in a 555. The implementation of such a NOR gate with 555 is shown in Figure 2.
Figure 2 Implementation of NOR gate with 555
A NOR gate is said to be a minimum set for implementing logic functions, since NOR gates can be made into any other logic gates. But it still would be better if other form of basic logic gates made from pure 555 can also made. One obvious logic gate with a 555 is the inverter, which has actually been shown above in Figure 1 (see pin X'). To implement digital sequential systems or state machines, a form of memory such as a clocked flip-flop is needed. A 555 chip contains an RS flip-flop, so it makes real sense to try to make use of it as a clocked flip-flop. The main difficulty on using this internal flip-flop is that the R and S inputs are fixed to other components inside the 555, namely the comparator outputs. By carefully controlling the signaling of input pins connected to those comparators, one can obtain a level-triggered as well as edge-triggered D flip-flop with a 555. A positive level enabled D flip-flop with 555 is shown in Figure 3. To make this edge triggered, we can actually make a master-slave arrangement but since this would require a larger amount of 555s, in this work we built a short pulse generator instead to make the level-triggered flip-flop into an edge-triggered one. The circuit on Figure 4 is a negative-edge triggered D flip-flop designed using the above approach.
Figure 3 Level-enabled D-flip flop
Figure 4 Negative edge triggered D flip-flop
The logic between data and clock sources inputs with the 555 can be made with 555 logic (using NOR and NOT gates), and the resulting circuit realization is shown in Figure 5.
Figure 5 A 555-logic-oriented implementation of circuitry for D flip-flop with 555.
With these NOR gate, NOT gate, and a edge triggered D flip-flop made solely from 555, it is time now to test this concept in real scenario. An added bonus for this 555-logic concept is that the same 555 can be used as the clock source.
Case study: synchronous 2-bit grey code counter Let us now consider a 2-bit grey-code counter that counts in this following order: 00, 01, 11, 10. A synchronous topology is chosen in this case study to emphasize the synchronously clocked sequential digital circuitry can be made. Using a general state machine topology, where states are fed back to flip-flops that holds the state information, through some combinational logic block, we can try to implement the following truth table: Q1 Q0 NextQ1 NextQ0
0 0 0 1 0 1 1 1 1 0 0 1 1 1 1 0
Using sum-of-product and simplifications principles, we can get: NextQ1 = Q0 NextQ0 = not Q1
The implementation of the above logic function can therefore be made as seen in Figure 6.
Figure 6 Test circuit of synchronous 2-bit grey code counter
The circuit on figure 6 implemented with only 555s (except timing R and C for clock generation and series R for LED indication on outputs) is shown in Figure 7. The clock generator is a 555 astable multivibrator circuit with R1 = R2 = 1k2, and C = 100uF.
Figure 6 A 2-bit synchronous grey-code counter implemented with 555s.
A video showing real experiment of the circuit can be seen in the following video link: http://www.youtube.com/watch?v=jpmp9uvjrwU
Conclusion: 555-logic proposed in this work relies on NOR gates (needs three 555s, OR one 556 and one 555), NOT gates (needs one 555), and negative-edge triggered D flip-flop (four 556s and six 555s).
This is the Power diagram off Motor forward reverse ,to change the motor direction we must change the one polarty for example R to S, for detail please see below:
for the control system, please see the diagram below:
for the Ladder diagram in PLC , first make the I/O addressing:
Posts
