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Lab 10 - Analogue + EEPROM

The 16F1937 PIC Microcontroller has 14 Analogue inputs. Newer devices have even more. An analogue signal with a voltage between Vss and Vdd on one of these inputs can be translated into a 10-bit digital binary number. We can choose to simply use only the 8 MSB’s of this 10-bit number or we can use the whole 10-bit number. Be aware that working with 10-bit numbers in an 8 bit controller like the PIC, needs to be planned into your program writing.

EB006 Options	Setting	Jumper settings (EB006)	Jumper settings (HP488)
Power supply	External, 14V	J29: PSU	J29: PSU
PICmicro device	16F1937
Programming method	USB	J12,13,14: USB	J20: USB
Clocking method	XTAL	SW2: XTAL	S2: XTAL
R/C clock speed
Xtal frequency	19 660 800 Hz
LVP Jumper selection	I/O Port	J11,16,17: I/O Port	J15,16,18: I/O
Port A E-block	Sensor board
Port B E-block	LED board
Port C E-block	Switch board
Port D E-block	LCD board
Port E E-block	Patch board

Build > Project Options... > General Options	Build > Project Options... > Configure
Options Setting Clock speed 19 660 800 Hz Simulation speed 10	Options Setting Device 16F1937 RC/XT XTAL Watchdog timer Off

Binary code training, using a hardware macro (A/D), working with 8 or 10-bit analogue inputs, using the Eeprom to create a data logger. 8 and 10 bit accuracy.

Analogue inputs, LED’s, logic output levels, LCD’s, switches, EEPROM memory, LDR sensor, Temperature sensor, Prototype board usage.

Construct the system shown from E-blocks.

In the course navigate to the ‘Flowcode step-by-step’ and review the section on Simple Hi-Fi (step 12) and Strings and Memory (step 11). The descriptions of the Multiprogrammer board , the switch board, the LCD, the sensor board, the prototype board and the led board are in the E-blocks section.

Look into the 'Help' menu and function in Flowcode to get the info you need.

Take your time to do these labs. It’s all starting to come together now. Divide a big lab task into smaller manageable items and only if you have the answers for all these questions you can go on and put them all together.

Letter	Meaning
L	Lab x
B	Basic complexity
I	Intermediate complexity
E	Expert complexity

L10-B1

Display an 8-bit analogue number between 0 and 255 on the LCD, that is the digital equivalent of the analogue voltage input provided to the PIC by the LDR (Light Dependent Resistor) on the Sensor board. Download the program to the PIC and test it. Place a voltmeter or an oscilloscope between the analogue input of the PIC where the LDR is connected to and GND of the PIC.

L10-B2

Display an 8-bit analogue number between 0 and 255 on the LCD, that is the digital equivalent of the analogue voltage input provided to the PIC by the variable resistor on the Sensor board. Download the program to the PIC and test it. Place a voltmeter or an oscilloscope between the analogue input of the PIC where the variable resistor is connected to and GND of the PIC.

L10-I3

Translate the number between 0 and 255 of the exercise above into a voltage reading between 0 and 5V. Make the reading as accurate as it can get in this 8-bit mode. Download the program to the PIC and test it. Use a voltmeter to check if the LCD displays the voltage correctly.

L10-B4

Display a 10-bit analogue number between 0 and 1024 on the LCD, that is the digital equivalent of the analogue voltage input provided to the PIC by the variable resistor on the Sensor board. Download the program to the PIC and test it.

L10-I5

Translate the number between 0 and 1024 of the exercise above into a voltage reading between 0 and 5V. Make the reading as accurate as it can get in this 10-bit mode. Download the program to the PIC and test it.

L10-I6

Develop a program that allows you to monitor when the lights are on and when they are off in a certain room, during a 24 hour period, using the LDR on the Sensor board. Use the EEPROM inside the PIC to store the light measurements. You want as many measurements as possible stored in the EEPROM over a 24 hour period. The 16F1937 PIC has 256 bytes of EEPROM memory on board. Figure out what the timing interval of the measurements should be and start programming. When you come back after 24 hours you should to be able to display all these stored EEPROM values one by one on the LCD, with the corresponding number (EEPROM address 0-255) next to it. You should be able to scroll through them by pressing SW0 or SW1. Make the intervals much smaller to test it before you give it a 24 hour run. Download the program to the PIC and test it.

L10-I7

Draw up the full circuit diagram of the PIC with the LDR and the LCD correctly connected, including the clocking circuit, the reset circuit, VDD and VSS connected to the PIC. If you were to actually prototype the circuit of this drawing, and connect power to it, it should behave exactly the same as the E-blocks system in front of you. Schematics in the E-blocks section and the full circuit diagrams in the datasheets of the E-blocks will come in handy when you do this task.

L10-I8

Connect the prototype board to port E of the Multiprogrammer and build your own 10 bit accurate temperature measurement using either an LM35 (°Celcius) or an LM34 (°Farenheit) temperature sensor. Read the datasheets of these components before you start. Display both the digital measurement (0-1024) and the actual temperature on the LCD. Download the program to the PIC and test it. Use a correct voltmeter and maybe even a thermometer to check your result.

L10-E9

Use the EEPROM in the exercise above to make your own 10-bit accurate temperature logger. Lets say that you want to log the temperature of a certain room in a house during 24 hours and with 20min intervals. This is quite similar to the logger you developed for the LDR, except this one needs to store 10-bit data in an 8-bit wide EEPROM. When you come back after these 24 hours you need to be able to display all these stored EEPROM values one by one on the LCD, with the corresponding number (EEPROM address) next to it. You should be able to scroll through them by pressing SW0 or SW1. A blinking LED indicates if the logger is still logging. After the 24 hours are passed, all LEDs should be on. Download the program to the PIC and test it.

L10-I10

Draw up the full circuit diagram of the PIC with the Temperature sensor and the LCD correctly connected, including the clocking circuit, the reset circuit, VDD and VSS connected to the PIC. If you were to actually prototype the circuit of this drawing, and connect power to it, it should behave exactly the same as the E-blocks system in front of you. Schematics in the E-blocks section and the full circuit diagrams in the datasheets of the E-blocks will come in handy when you do this task.