PIC Projects
WiFi - ESP8266
Doorbell with SD / EEPROM
SD FAT16/32 for .bmp
TFT Egg Timer
LCD TFT Oscilloscope
SD Talking Clock
SD Sound Recorder,
    FAT32 wav Player
LED Thermometer
LED Egg Timer
LCD Egg Timer

Frequency Counters
100KHz For PC
1MHz For PC
8 Digits LED 50 MHz
Scope Screen Display
LCD Module 10MHz
6MHz for Android
USB PIC18F2550
USB TFT display BMP
USB DS18B20 Sensor
USB Thermometer
USB Counter
USB Meter
USB Oscilloscope
USB Input-Output
USB 16x2 LCD

COM & LPT Ports
MCP3201 on LPT
Serial TFT Text
Serial Inputs Outputs
Serial Port LCD
Analogue Signal to LPT
MCP3201 on Serial Port
Serial Thermometer
Analogue Signal to Serial
LCD Display on LPT
Serial Thermostat

Water Softener
HP Stream 7 docking
3.7V to 5V
Solar Charger

Infrared Decoder
PIC Music

Code Lock
Code Lock with LCD


Updated on 17/01/2016 (a and b segments were swapped on drawing)
Counter based on PIC16F628A . Included C code and circuit diagram. Displays -55 to 125 centigrade.
The temperature is read every 15 seconds, can be changed in the code. The math is using integers to calculate the degrees and the tenths of degrees are calculated separately.
The 7 segment LED is common cathode, 4 separate digits can be used with segments a to g linked.

You are free to use the circuit diagram and the software with no limitations.

Circuit Description
See also Technical Tips

All transistors are BC337 or equivalent.
Total 5V supply current is 90mA.
The 4 digits display is common cathode, the 7 resistors of 220 ohms enable current of 15 mA for each segment which is on for 25% of the time. The seven segments, a to g, of one digit are linked to the corresponding seven segments in the other digits.
Segment e is connected differently because RA4 is an open drain output.
The 4 digits are multiplexed by pins 6-9 that drive the common cathodes cc1-cc4.
DP is the decimal point.
DS18B20 can be any type.