User Manual - Microtronics Pakistan
Contents
1. Microtronics Pakistan Invent Future User Manual 1 i 1 Amer Iqbal Qureshi www electronicspk com info electronicspk com Lab Il USB User Manual 2 Lab II USB ongratulations on purchasing Microtronics Pakistan PIC Lab II USB development board This board can act as both development as well as trainer to help you learn and explore Microchip PIC Microcontrollers The Lab II features PIC18F2550 micro controller from Microchip This is a 28 pin mid range 8 bit microcontroller with 32KB flash program memory The special feature of this controller is that it has built in USB 2 0 slave module so you can learn and explore how to make USB compliant devices Another special fea ture of this and other PIC microcontrollers is ability to self program This ability has been utilized by some developers to upload the new hex file using serial or USB interface thereby eliminating the need of an external hardware programmer ar 1 1 5 1 B 1 3 i Fo a 1 1 i 2 1 1 PIC Lab II USB has many commonly used peripheral devices pre fabricated so that you can learn to use them as well as incorporate them in your project as per your requirement The devices have been pre connected to the microcontroller IO Lines through DIP switches that2. Write line is con nected to ground to configure the LCD in Write mode only Although header has 16 pins data lines DO D3 are nor connected Thus the board configures the LCD in 4 bit mode The connec tions to microcontroller are Usually 23 djus t LCD Pin Microcontroller Port able through a variable resistor Register Select RS RB2 This board however provides a RB3 a RB4 Sistor There 1s also no associated DIP RBS switch to connect or disconnect oe RB6 the IO lines If LCD 1s inserted RB7 Lab Il USB User Manual 5 the lines get connected and if you want to use these IO lines through headers for some LCD1 LMOT6L other purpose you can remove the LCD The connector 15 general type and can accept all LCDs that have pin connections and con troller compatible with HD44780 LCD con troller You can get various models of LCD with dif ferent display characteristics Commonly available ones are 8x1 8 characters and one line 16 2 16 characters per line 2 Lines 16 X 4 16 characters per line 4 lines 20 4 ines 0 20 characters line 4 lines LCD Schematic Connections LCD Inserted into The LCD Interface Header Relay Relay is required in microcontroller applications where you want to switch a heavy AC or DC load through mi crocontroller PIC Lab II USB has a standard 12V relay It 15 powered through external DC adapter Therefore you can not use it when board is bei
3. a conventional programmer yet in certain circumstances you may want to override the bootloader and program the controller through standard programmer debuggers like PicKit 2 This board therefore has standard In Circuit Pro gramming header where an external programmer debugger can be attached The pin orientation 15 fairly standard as per Microchip recommendation USB 2 0 PIC18F2550 has built in USB 2 0 communication module This module can be used as USB slave It can perform to Full speed standards and using appropriate descriptors all types of USB 2 0 com pliant devices be made Lab Il USB User Manual 11 DIP Switch Configuration In Circuit Programming 1 211 21 VVVVVVVV DIPSW_8 20 DIPSW_5 Lab Il USB User Manual 12 II USB ic of PIC Lab Schemat ov Nesey Nesey CLr UDO 89 ugok WlLHOd ETH asn 950 0 gt LAA Cla ATA lt a 1 54 k AAAAAAA FL 81 Zl Sh EL ch 05504814 dadtad gH Sod clayey ddSSD 01l8H LNY FSH VOSN0S 0LD
4. and connect the data an ground pins to your analog data source Please note we have assumed an exact 5V supply VDD to calculate the 1 25V it will be better to measure the VDD volts first and then divide that figure with 4 to get what should appear at zener anode pin 12 Communication communication protocol is commonly in electronics to make a network of devices The PIC Lab II USB board has two such devices integrated on board A serial EEPROM and a Real Time clock The can be implemented using software techniques however 18 2550 many other modern controllers have a hardware module built into the controller to manage this task The 12 is implemented through MSSPI module that contains many other communication protocols It use SDA and SCL lines for 12 communication The SDA and SCL are located on RBO and RB1 Lab Il USB User Manual 9 pins The two lines are connected through two Dip Switches with SDA and SCL labels The I2C Bus in PIC Lab II has two 10K pull up resistors on SDA and SCL lines 12 EEPROM 12 EEPROM consists of one memory chip from 24 family 24 06 is supplied by default with the board however if you want to replace it with another one you can easily do so by taking the chip out of socket and replacing with one having lt more memory like 24C512 has 512K bits 64 KB memory You can have up to 5 such chips on one Bus The individual chips are then addressed
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6. Hz signals maximum Thus you can measure frequencies up to 6 Infra Red Remote Control Sensor Today infra red remote controls for are available at very low price This can be used to give inputs to your application using the infra red remote sensor This technology uses only one line of microcontroller and you get the facility of a number of switches Indeed you can say we get a serial keypad with 20 or more keys The IR remote sensor senses only 38Khz modulated pulses given out by remote controls thereby eliminating interference by infra red light in environment The sensor is connected to RA3 pin of microcontroller through the DIP switch Some compilers like Proton Basic provide decoding libraries to decode the Sony and Philips remote controls Others do not have such libraries pre built and you will need to make the code yourself to decode the sig 8 IR Lab Il USB User Manual 7 nals Dallas One Wire Micro Lan Network 1 Wire is a device communications bus system designed by Dallas Semiconductor Corp that provides low speed data signaling and power over a single signal 1 Wire is similar in concept to but with lower data rates and longer range It 1s typically used to com municate with small inexpensive devices such as digital ar ters and weather instruments A network of 1 devices with an associated master device is called a Mic
7. annels distributed to various pins these pins are available through standard headers and can be used to acquire analog data The PIC18F2550 input pins can tolerate a maximum of 5 2V dc voltage More than that is likely to damage the controller circuitry External signals where there 15 chance of voltages higher than this Lab Il USB User Manual 8 needs a pre conditioning circuit to protect against accidental dam age or scale down the voltage to bring it into the acceptable range PIC Lab II USB has one channel circuit for this The circuit essen tially consists of a potentiometer which acts as a voltage divider He slider selects the ratio of resistance above and below The center point gives the output volts divided by the voltage divider This is protected by 5 1 zener diode so that any accidental spike gets to ground through zener The Input pin is further protected by a 470 ohms resistor in case the pin is made output accidentally and pot is connected to ground The analog input channel connects to RAO pin of the microcontrol ler through Dip Switch 15 a three pin male header for acquiring analog data The central pin collects analog signal whereas the two other pins connected to 5V DC and ground respectively Thus 2 this header be used to give out 5V supply to an analog sensor as well If you want to acquire analog signal that has its own supply only use data and ground pins Confi
8. can be used to con nect or disconnect a device as per your needs All IO lines have also been brought out as standard 0 1 male jumpers grouped together as microcontroller Ports along with 5V power supply for easy connections with your project circuit that needs to be controlled by the controller The board can be powered through external 9 12V DC adapter or through USB connection of the host computer Lab I USB User Manual 3 Features In a Glance 8 2550 Microcontroller Supports other 28 Pin Microchip PIC Microcontrollers Character LCD interface HD44780 compliant standard LCDs Supported USB Type B connector implements USB 2 0 Slave features with 18F2550 12 EEPROM All 24CXXX Chips are supported 24C08 included I2C Real time clock with battery backup DS1307 included One SPDT 10 relay 38KHz IR Remote sensor Dallas One Wire device connectivity DS18B20 digital temperature sensor One channel ADC with voltage divider 5 1 zener protection circuit Three tactile push switches Rest switch can be used as tactile switch with proper configuration settings for MCLR Two channels of PWM with Low Pass filter and OP AMP current booster A Pre Amp to acquire low power frequency input to measure external signal frequencies Standard In Circuit Programming header as per Microchip standard for use with PICkit 2 One user programmable LED 20 MHz Crystal Oscillator 18F2550 can be configured to run at 483MHz on
9. guring the Voltage Divider The voltage divider can be used to scale down the input signals or to act as analog simulator For example if you place a short jumper across the VDD and data pin J1 header the POT will get SV or VDD as input signal Now rotating the pot slider will send voltages from 0 to 5V to the input circuitry that you can experiment with If you have an analog signal say up to 12V you would like to scale down it to range First dis connect the Dip switch for ANO so that high volts do not reach the controller Lets scale down the input volts by 4 times Thus a 12V will appear as 12 4 on microcontroller line which is well within safe range All other lower volts will also be scaled down similarly We can multiply the measured volts with 4 in software to get the actual volts So make sure Dip is Off put a short jumper on VDD and data pin so that 5V reach the POT Now we have to measure the volts using a multi meter at the center pin of POT As you can see in the sche matic above the anode of zener diode is connected to this point you can easily measure the volts at anode of zener which 15 close to the POT The point is shown by arrow in the above figure Now to scale down the SV by 4 5 4 1 25 rotate the pot so that you get 1 25V at this point Once you get 1 25 leave the pot at this position now it is dividing the input volts by 4 Now remove the short jumper and turn on the Dip switch
10. ng powered through USB 1 The relay is connected through DIP switch to of microcontroller The relay is powered through NPN transistor which does not isolate it from the mi crocontroller therefore beware when using with AC load For a serious application better get a spate module with relays optically isolated from microcontroller a Relay Circuit 2 804 Lab Il USB User Manual 6 The outputs of relay are available as a T Block screw connector With common in center and Nor mally open and normally closed connections on either side Relay Module with T Block Screw Terminal This relay can handle a 10A load AC or DC Frequency Clock Pulse Input Frequently in microcontroller applications you have to measure the frequency of incoming signals TTL level of signals can be directly fed to the microcontroller pin but low powered signals need to be amplified a little bit Moreover many signals are not square waves and they tend to be sine or triangle wave We need to convert those signals to TTL type before they can be reliably counted PIC Lab II USB has a pre built small amplifier con ditioning circuit for this job The CLK output of this preconditioning circuit is fed through DIP switch to RA4 pin of Microcontroller The RA4 pin is also TOCKI Timer0 Clock In Thus external pulses be Frequency Input Circuit counted by the Timer0 The RA4 pin can respond to 60M
11. ply from IO headers 18 used only to supply the power and not to get power from other boards Two devices namely Relay and LM358 operational amplifier do not get power from 5V source indeed they get 9 12V supply from the external source Thus relay can not be turned ON from USB supply Similarly DAC signals can not be produced from USB power supply More details on Lab Il USB User Manual 4 this will be given in relevant sections Character LCD Interface Character LCDs are commonly used in microcontroller projects to interact with user or display values of variables etc Hitachi HD44780 is a popular LCD that is used A number of other manu facturers are also making compatible LCDs The PIC USB board has an interface for this device A female type header with 16 connections is available that will accept the standard LCD The interface has supply for LCD backlight Following are the standard pin configurations of HD44780 character LCDs 16 Backligt Cathode Ground 2 VDD ve 3 VE Contrast Voltage 4 Register Select 5 Read Write 6 Enable 7 0 8 Data 1 9 Data 2 lt 10 Data3 11 Data 4 12 Data 5 13 Data 6 14 Data 7 1 15 Backlight Anode ve 4 4 16 602 4 1 HD44780 Character LCD Pinout The LCD has 8 data lines and 3 control lines PIC Lab USB LCD interface uses 4 data lines D4 D7 and 2 control lines Register Select RS and Enable En The Read
12. roLan One distinctive feature of the bus 16 the possibility of using only two wires data and ground accomplish this 1 wire devices include an 800 pF capacitor to store charge and power the device during periods when the data line is active It is not a compulsion to use only l wire you can power up the device using standard power supplies if you want PIC Lab II USB has 1 wire header available for connecting either a single device or a network of devices DS18B20 is the most commonly used de vice for this This is a digital thermometer and can be directly plugged into the connector or you can make a microloan The 1 wire network connects to RA2 pin of microcontroller through Dip switch Please note the center pin on connector is the data pin the one above is VDD 5V and the one below is GND User Programmable LED A user programmable LED 18 also on board to indicate program status in your applications This Dallas 1 wire Circuit also helps in starting as blinking an LED 1s the usual program one writes to test the application The LED 15 active high This means the cathode is connected to ground and anode connected through a current limiting resistor to microcontroller The LED is connected of microcon troller through the Dip Switch Analog Input Channel Many applications need to interact with analog data A large number of sensors give analog data as their output The PIC18F2550 has 13 analog input ch
13. t circuitry for the microcontroller When pressed the microcontroller gets a warm re boot All RAM is cleared and program restarts from the first instruction In case there is bootloader in the controller it starts again and if you have a new program it be downloaded In PIC18F2550 the MCLR pin can be configured as RE3 and therefore the reset switch can be used as fourth digital Input Pulse Width Modulation and Analog Output Lab II USB has two channels of analog output The analog signal is generated through two PWM channels 8 2550 The raw digital output of these PWM channels is available at RC2 and In order to convert this data into true analog output one needs a low pass filter and a buffer circuit PIC 6 USB has two low pass filters and an LM358 OP AMP voltage follower cir PUSH Switches Lab Il USB User Manual 10 cuit to produce a clean analog signal directly usable by many devices The Power supply for LM358 comes directly from external power source which is 9 12V This is because the OP Amp can not go rail to rail output equal to its supply volts Thus if the LM358 was powered from 5V it will not be able to generate more than 4 5V on its output Please note the cut off frequency of this low pass filter 15 about 160 Hz In Circuit Serial Programming LMS56N Low Pass Filter and Buffer circuit for PWM output Although bootloader in PIC Lab II USB frees you from using
14. the same crystal On board 5V 1A power supply regulator for external DC adapter 9 12V Selection jumper to select power supply source external adapter or USB All IO lines available as 0 1 headers for easy expansion Standard FR4 double sided PCB with plated through holes Dimensions 3 x 4 inches All Devices can be connected or disconnected to microcontroller lines via Dip switches Powering The Board The board can be powered through an external 9 12V DC supply or through USB host computer Most of the times when developing an application it is more convenient and practical to power the board through USB However remember the capacity of USB to supply current is limited The re quirements of board itself including LCD is not much and can be provided by USB safely However case you also want to power the external device through this board like motors or an array of bright LEDs it will be better to use external power supply that case you will still be able to program over USB Close to the USB connector there is a jumper with three headers This selects the supply source be tween external or USB A red LED in power section shows the status of supply The external power supply will also be useful in cases where after programming the board is sup posed to run without computer as a standalone de vice power supply is also available for sion cards etc through the IO headers Make sure the power sup
15. using AO A2 pins The chip on board will have this address set to 0 I2C Real Time Clock DS1307 15 a standard and very commonly used real time clock and calendar chip that uses I2C protocol The chip has been provided by its own 32 7868KHz crystal as well as a Lithium ion battery to backup the timing circuitry even when the board has been powered off The sout pin of DS1307 15 unimple mented 12 Bus Schematic Extending 126 Bus In case you have another device that needs to be attached to the PIC Lab II it can be done sim ply by attaching its SDA and SCL pins to and RBI on extension headers In that case you do not need to connect the SDA and SCL Dip switches The external device then should have its own Pull Up resistors In case you also want the services of on board devices and external device as well just turn the SDA and SCL dip switches ON and connect the external device to RBO and pins along with GND If the external device also needs power it be supplied through ex tension header Push Switches SW1 SW2 and SW3 PIC Lab II USB has three user programmable push switches These switches are active Low with 10 Pull up resistors He switches are connected through 3 Dip Switches to RCO RC6 and respectively The RC6 and RC7 are also used for serial communication Reset Switch RST There is a fourth switch labeled as RST on board This is the reset switch and implements rese
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