GP2D12 distance sensor 1N5819

During 250 ms, sensor is configured as a light sensor (powered), C1 charges through D1 up to SENSOR+ voltage. Low drop regulator U1 generates a 5V regulated supply. Q1 is blocked by D2 (D2 maintains base to a voltage higher or equal to its emitter voltage), so GP2D12 is not powered. Q3 is non-conducting too, preventing current flow through D3/R5/Q2. So the only significant current diverted from C1 charging is through R1 (less than 2 mA), and at the end of this phase C1 is fully charged.

During the following 50 ms, sensor is configured as a touch sensor (passive). SENSOR+ is now only pulled up to +5V through 10Kohm (inside RCX), insufficient to block Q1. Q1 and Q3 are then conducting, and GP2D12 is powered. Q2, mounted as an emitter follower, buffers GP2D12 output and its value is available to RCX through D3 and R5.



Sample code to read sensor:

    SetSensor(SENSOR_1,SENSOR_LIGHT);
    
    Wait(25);
    
    SetSensor(SENSOR_1,SENSOR_TOUCH);
    
    Wait(5);
    
    SetSensorMode(SENSOR_1,SENSOR_MODE_RAW);
    
    distance=SENSOR_1;
    
    SetSensor(SENSOR_1,SENSOR_LIGHT); //Enable C1 charge as soon as possible



Component selection

    D1 prevents destroying the sensor in case of reverse connexion. I didn't use the full bridge rectifier used in Lego sensor that enables sensors to work when connected backwards (number of needed diodes jumps from 3 to 8 !). I considered that someone able to build this sensor is also able to connect it in the right way... For those who want it, here is the diagram with full bridge rectifier.
    I used 1 Amp. Shottky diode 1N5819 for D1, inexpensive and readily available. Its low forward drop foltage is less than 0.1V for the current that flow through it, this enables to charge C1 to the highest voltage possible.
    C1 stores energy that will be used during measure phase, it must provide 5V at the end of this stage. Assuming typical values for GP2D12 (I=35mA, conversion time=50ms) and an initial 7.5V across C1, its value is C = I * dT / dV = 35 * 50 / (7.5-5) = 700 µF. Small margin with 1000 µF...
    U1 is a low drop out 5V regulator in TO92 case. I used a Telcom/Microchip TC55RP5000, but other regulators will probably work, such as STMicroelectronics L4931-50. Standard regulators such as 78L05 will NOT work because they require more than 7V at input to get a 5V output. Take care with some low drop regulators such as LM2931 that require more than 25 mA when powered at 1V. With RCX current limitation, this hog eats all energy. (I was caught with this one...)
    Q1 switches power on and off for GP2D12. At 35 mA current, I originally used a plain-vanilla BC548. My sensor began to work with it, but exhibited strange behavior. Looking to GP2D12 power supply I then discovered 2V dips ! I then looked at GP2D12 consumption and discovered that it was pulsed (220mA pulses 1/8th of time, supperposed to a 8mA constant current. See oscilloscope captures here). At such a current, BC548 has a low gain, and since I couldn't lower base resistor R1 (main current drain during capacitor charge) I used a high performance Zetex transistor, ZTX718 that offers high gain at high current (other similar devices can work!).
    C2 stabilizes U1 and helps absorb peaks of current. A low ESR version would be better (see "grass" on 5V output when GP2D12 works).

User Interface - Lcd Driver Based On The HT1621 Controller

Application Note Abstract This Application Note describes implementation of a liquid crystal Display (LCD) driver based on the widely available HOLTEK HT1621 LCD Controller Methods and algorithms of Display control are described and an API library is provided. The LCD used in this example was a customer’s custom part. The proposed algorithms CAN be easily adapted to any custom LCD panel connected to the controller. Introduction LCDs are widely used as data Display devices in embedded systems. Among the features that have made LCDs popular are low price, low power dissipation, lightweight, durability, reliability, and broad support by dedicated ICs for Communication with Microcontrollers A good example of an LCD Driver is the Hitachi character LCD Driver HD44780, the industry standard. This dot-matrix LCD Controller is supported by PSoC APIs. It is useful in applications that permit alphanumeric data Display However, specialized Displays are often needed. Specialized Displays keep end- product prices low, simplify the Interface between the Microcontroller and LCD Driver and decrease weight and size parameters. Examples of specialized Displays include Clocks calculators, telephones, and home and industrial appliances. This implementation is based on one of these dedicated drivers, the HT1621. This Application Note addresses the proposed implementation in two parts: ƒ General Description ƒ LCD Driver Implementation General Description The HT1621 driver is a 128-segment (32x4), multi-functional LCD Driver with memory mapping. The software configuration feature of HT1621 makes it suitable for many LCD applications, including LCD modules and Display subsystems. Only three or four connections are required for interfacing between the host controller and the HT1621. A structural schematic of the Display system is shown in Figure 1. This structure requires few external components and uses only three Interface connections. The system consists of the PSoC, HT1621 controller, and an LCD panel. The HT1621 besides its primary function as an LCD controller, has peripherals including the watchdog Timer time base generator and the Tone frequency generator. For more information about these features, refer to the HT1621 data sheet. Note that the controller has an on-chip RC Oscillator (256 kHz) for controlling the LCD and peripherals. This General Description focuses on the components and functions of the HT1621 driver that relate directly to the LCD: ƒ Display Memory RAM ƒ LCD Driver in HT1621 ƒ Command Format ƒ Interfacing with HT1621

Final Project - Ping Pong Shooter L7805CV

The Ping-Pong shooter, as its name, is able to shoot Ping-Pong balls, and the machine can simulate a real-world situation that if there is a player in front of it, it starts shooting; otherwise, it stops working

Criteria of Success
1. A machine that can shoot
2. Able to control the machine i.e. control weather the ping-pong ball will shoot or not
3. Able to control the system with a laser dependent switch


How it works:
The ping-pong shooter mainly contains three parts
1. A switch that is depends on a photoresistor and a light source(laser beam)
2. Two DC motors to shoot the balls
3. Stepping mother which acts likae a gate to control the flow of the ball


Main Component

    Photoresistor
    DC motors
    Stepping Motor (a8byj-48)
    Micro controller (89S51)
    Octal high voltage high current Darlington transistor arrays (ULN2803)
    Voltage regulator (L7805CV)



    A ULN2803 is an intergrated Circuit (IC) chip with a HIGH Voltage/High Current Darlington Transistor Array. It allows you to interface TTL signal with higher voltage/current loads
    The chip takes low level signals (operate at low voltages and low currents0 and acts as a relay of sorts itself, witching on or off a higher level signal on the opposite side.
    


    The 78xx family is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost
    I.E. 7805=5V   7812=12V
    Disadvantage: Input voltage always needs to be higher than the regulated voltage

Miscellaneous Component

    Resistor (10k ohm *2)
    Capacitor (33 pF*2,1000nF*1)
    Oscillator(12MHz*1)
    Wires
    PVC tube (2" Diameter)

Water towers water level controller circuit PC817

IC2 can use a variety of 555 time base integrated circuits. IC3 is the infrared receiver decoder CX20106A. IC4 can use 4N25, 4N26, PC817 and other optocoupler. Part of the infrared receiver can purchase finished infrared receiver components or integrated infrared receiver,it’s easy to produce and improve reliability. VD1, VD2 and VD3 ​​can use infrared transmitter and receiver diodes of TVremote control. J chooses to use ​​a new selection of memory self-locking relay,the shape of this relay is same as the general replay, the difference is that the pullis not required to maintain current,justwhen pulling and releasingit requires a certain pulse drive power, then the mechanical structure maintains locked state.

Car Audio Amplifier TDA1557Q TDA1553Q

This stereo audio amplifier is for car purpose and can deliver up to 2 x 22W using a single TDA1557Q or TDA1553Q IC from Philips.