C Programming Using CCS Compiler For PIC Microcontrollers
Here is a link for good tutorial of programming PIC microcontroller in C.
http://harfordhackerspace.org/2010/02/programming-pic-microcontrollers-in-c/
Motor Control using Pulse-Width Modulation (PWM)
In this program, a jumper on Port B directly selects the PWM output. PWM output is only present if a jumper to ground is present on one the least significant 3 bits of port B.
The program demonstrates the use of control registers to effect PWM operation. One thing to notice is the fact that the program waits for a change on the input pins before selecting a new pulse-width duty cycle and reloading CCPR1.
Wednesday 1 June 2016
Tuesday 31 May 2016
PCB Know How
Generic
Standard on PCB Design (IPC2221A)
PCB
Rigid Laminate material (FR4, typically) consisting of
a glass epoxy substrate clad with copper on two sides for double sides (0.062”
typically)
PCB
fabrication Gerber data requirement
1 1) Top
Electric (Art work)
2 2) Botton
Electric (Art work)
3 3) Top
Slilk (Art work)
4 4) Top
Resist (Art work)
5 5) Plated
Through Hole (N.C Drill)
6 6) Non-Plated
Through Hole (N.C Drill)
7 7) Board
Outline (Art work)
8 8) Drill
Table
Electrical Isolation (Creepage Vs Clearance)
Electrical
Clearance
AC and pulsed voltage > 200V must consider
dielectric and capacitive effect of substrate in addition to spacing.
Minimum spacing requirement according to withstand
voltage are as below
Withstand
Voltage (V)
|
Minimum
Spacing (mil)
|
0 ~ 30
|
3.9
|
31 ~ 150
|
24.0
|
151 ~ 300
|
49.2
|
301 ~ 500
|
98.4
|
Electrical Isolation (Creepage Vs Clearance)
Creepage is the shortest path between two conductive
parts measured along the surface of the insulation. Clearance is the shortest distance between tow
conductive parts measured through air.
Copper Weight
1 oz of copper will cover one square foot area when
rolled out to a thichness of 0.0014 inch or 1.4 mil.
Copper
Weight (oz)
|
Thickness
(inch)
|
½
|
0.0007
|
1
|
0.0012 ~ 0.0014
|
2
|
0.0028
|
PCB Surface Finishing
Different types of PCB finishing are as below
1) Hot
Air Solder Level (HAL or HASL)
2) Hard
Gold-Electro plated gold
3) Electro
Less Nickel Emersion gold
4) White
Tin
5) Organic
Solderable Preservative (OSP)
The most common surface finishing we can see is Hot
Air Solder Leveling. In this process, Panels are processed through a bath of
molten solder, conversing all exposed metal surfaces. High pressure hot air,
directed at both sides of the panel simultaneously, removes excess solder from
the holes and surfaces.
PCB Trace Width vs. Current Table
A PCB trace width vs. current table helps you understand the relationship between PCB trace width and current carrying capacity so you can determine the required trace width for your printed circuit board design.
Monday 30 May 2016
Microphone Pre-amp
R1, R2, R3,
R4 & R8 : Low excess noise metal Film
C1, C2
& C3 : Input and output coupling
C4 : Noise
filter, C5: by pass
NOTE: Input
Cable to microphone must be shielded
Sunday 29 May 2016
Relay Circuits
Momentary Relay Activation Circuit
Relay will energize
momentarily until the capacitor is fully (or partially) charged.
Relay coil produce brief
high voltage spikes when they are switch off and this can destroy transistors
and ICs in the circuit. To prevent damage, a protection diode must be placed
across the relay.
Controlling Multiple LEDs
Multiple LED Control Using Minimum I/O pins
Truth table for controlling six LEDs using three I/O are as shown below:
H = Output Set high (5V)
Truth table for controlling six LEDs using three I/O are as shown below:
H = Output Set high (5V)
L = Output set low (ground)
I = Input
More LEDs can be controlled by using this equation:
Numbers of LEDs = (Numbers of PINs) x ( Numbers
of PINs – 1)
For example:
Number of LEDs = 4 x (4-1)
= 4 x 3
= 12 LEDs
Speaker Volume Control Circuits
Speaker Circuit with Adjustable Volume Control
This is how we usually built 8/4/16 Ohm speaker with adjustable Volume Control. It can handle up to 15W speaker without any issues.
100V Line Audio Volume Control with bypass Option
This is 100V line speaker volume control with Emergency bypass. It requires DC 24V to bypass the audio level control.
This is how we usually built 8/4/16 Ohm speaker with adjustable Volume Control. It can handle up to 15W speaker without any issues.
100V Line Audio Volume Control with bypass Option
This is 100V line speaker volume control with Emergency bypass. It requires DC 24V to bypass the audio level control.
Buzzer Control
DC Motor/ Fan Monitoring
DC Motor/ Fan Failure Detection Circuit
Rsense = Sensing Fan Current
R1 & C1 = Establish an average DC level at the mid point of the transistor of the current waveform and apply this voltage to the base of Q1
This DC motor/fun failure detector checks for the fluctuation in current through Rsense. A static current causes the output to go high, indicating a failure.
Rsense = Sensing Fan Current
R1 & C1 = Establish an average DC level at the mid point of the transistor of the current waveform and apply this voltage to the base of Q1
This DC motor/fun failure detector checks for the fluctuation in current through Rsense. A static current causes the output to go high, indicating a failure.
Saturday 28 May 2016
Digital Input Sensing
Short Circuit Monitoring
Comparator Circuit for Open/Short Detection
At open circuit condition across +/- of the input connector, V- will get around 5.1V. Since V- (5.1V) is greater than V+ (2.5V), output to the microcontroller will be Low (0V).
When the short circuit is detected across +/- of the input, V- will get less than 2.5V which will make the output to go High (5V).
This circuit can be used for simple continuity test circuit by connecting LED and Buzzer at the output.
Telephone Ring Detector
Analog Telephone Ring Detector
When this circuit detects the telephone ringing signal across tip and ring (60 to 105-volt RMS 20-Hertz sine wave), it will trigger the Optocoupler's phototransistor output and provide Low (0V) signal to microcontroller. Otherwise, it will give High (5V) to microcontroller.
12V Zener is added to prevent fault triggering from unwanted signals. 0.1uF, 250V capacitor is used for DC blocking and 10k 0.5W resistor is to limit the current passing through the optosiolator.
12V Zener is added to prevent fault triggering from unwanted signals. 0.1uF, 250V capacitor is used for DC blocking and 10k 0.5W resistor is to limit the current passing through the optosiolator.
This circuit can drive relay or can be directly interface with any other outputs such as LEDs.
Fuse Monitoring Circuits
AC Fuse Monitoring
This is a simple AC Fuse monitoring circuit, which will give Low (0V) to microcontroller when the Fuse is Okay and give High (5V) if the fuse is faulty.
This DC Fuse monitoring circuit will give High (5V) to microcontroller when the monitoring fuse is Okay and gives Low (0V) when is fuse is faulty.
This is a simple AC Fuse monitoring circuit, which will give Low (0V) to microcontroller when the Fuse is Okay and give High (5V) if the fuse is faulty.
This DC Fuse monitoring circuit will give High (5V) to microcontroller when the monitoring fuse is Okay and gives Low (0V) when is fuse is faulty.
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