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Embedded Systems Programming Custom sensors for the use with Atmel ATmega8535 microcontrollers and the Kanda STK200 board Designed by Richard Anthony University of Greenwich. 1. New sensors for the ATmega8535. Light Sensor Connects to Analogue input ADC7 (pin 7 of Port A)

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Embedded Systems Programming Custom sensors for the use with Atmel ATmega8535 microcontrollers

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Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Embedded Systems Programming

Custom sensors for the use with

Atmel ATmega8535 microcontrollers

and the Kanda STK200 board

Designed by Richard Anthony

University of Greenwich

1


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

New sensors for the ATmega8535

Light Sensor

Connects to Analogue input ADC7 (pin 7 of Port A)

Reading increases as light intensity increases

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

New sensors for the ATmega8535

Floor-Switch Sensor

Connects to Digital input (bit 0 of any port)

When the mat is stepped on, the switch operates

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

New sensors for the ATmega8535

Passive Infra-Red (PIR) Sensor

Connects to Digital input (bit 2 of any port)

When a person moves, in detector range, the internal switch operates

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

New sensors for the ATmega8535

Magnetic-Switch Sensor

Connects to Digital input (bit 1 of any port)

When the magnet is moved in / out of range, the switch operates

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

New sensors for the ATmega8535

Twin Variable Resistor Sensor

Connects to Analogue inputs ADC2 and ADC3

(bits 2 and 3 of port A)

Rotating the dials changes the analogue

resistance values

6

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Thermistor (2)

Our custom temperature sensor can be connected to bit 6 of port A.

(Must be used on port A because it is an analogue device and needs to be sampled using the ADC).

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Thermistor (2)

Thermistor temperature sensor probe calibration

(8-bit values read as ADCH, i.e. most significant 8 bits)

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Humidity Sensor

Our custom Humidity sensor can be connected to bits 3, 4, 5 of port A (uses all three bits).

(Must be used on port A because it is an analogue device and needs to be sampled using the ADC).


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Sounder

Used in PCs, Christmas cards, alarm clocks ….

Low output current needed - can be driven directly from a parallel port pin.

Our custom sounder device is connected to bit 3 of the port.

You need to configure the pin for output and provide a pulse on the port bit 3.

See the Loudspeaker demonstration project provided.

10

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Motor with shaft encoder and H/W Interrupt generation

Motor

Can be driven via bit 3 of any port (‘1’ provides power to the motor).

Primarily designed for PWM using Timer/Counter0. Timer 0 Output Compare Match Output OC0 is the alternate function of Port B bit 3.

Motor can reach speeds exceeding 100 Revolutions per Second (6,000 RPM).

Motor stalls if driven with a duty cycle less than 29% (approximately 8 RPS).

Shaft Encoder

Comprises a ‘Slotted-Opto Switch’ (which detects when its light beam is broken) and a rotor with four cut-outs, enabling detection accuracy of ¼ rotation (i.e. 90 degrees).

If measuring rotational speed, four pulses represent 1 revolution.

The output of the Slotted-Opto Switch is connected to bit 2 of any port.

Primarily designed to generate a Hardware Interrupt INT0, which is the alternate function of Port D bit 2.

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Slotted Opto Switch

Rotor

Motor

Peripherals – Motor with shaft encoder and H/W Interrupt generation

Connections to Port B and Port D

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Slotted Opto Switch

Transistor driver circuit for motor

Rotor

Motor

Peripherals – Motor with shaft encoder and H/W Interrupt generation

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Shaft encoder

IR

LED

Infrared light beam

IR

sensitive transistor

(under rotor)

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

There is also a simpler motor rig that does not have the optical feedback system

Details will be added soon


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

8 Analogue outputs, one per stage to allow experiments

Bit 0

8 bit Digital data input

Bit 7

Resistors

Digital Signal Processing – D-to-A conversion with a resistor ladder

A simple 8-bit R-2R resistor ladder

(connects to any port, uses all 8-bits configured as outputs)

Converts a Digital value in the numerical range 0 – 255

into an Analogue value in the range 0 Volts to 5 Volts

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Digital Signal Processing – D-to-A conversion with a resistor ladder

Oscilloscope Earth connection

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Digital Signal Processing – D-to-A conversion with a resistor ladder

Oscilloscope Earth connection

18

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Accelerometer and X-Y axis Bar LEDs

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Accelerometer and X-Y axis Bar LEDs

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Output device - SERVO

Converts a control signal from a single digital output port pin into a precise rotational position (angle).

PWM is used to generate the control pulse width in the range 0.5ms – 2.5ms (1.5ms pulse indicates the ”neutral“ / central position).

Rotation: 180 degrees.

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Servo adapter board

Power (from supply) 5Volt to 6Volt

To Microcontroller port

To Servos

Ground from supply (0Volt)

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Servo adapter board

Signal (PWM pulse)

Power 5Volt to 6Volt

Ground (0Volt)

To Servo

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Servo adapter board

Two servos connected, using both Timer1 PWM channels

Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Servos in use (simple 2-servo robot)


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – InfraRed receiver

(RC5 command receiver, as in TV remote controls)

InfraRed receiver


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Radio Frequency Identification (RFID) reader

“Tag read”

Indicator LED

RFID reader

RFID tag


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals – Keypad

Provides a simple means of numerical data or control input.

The Keypad has 12 buttons arranged in a 4 Row * 3 Column Matrix:

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

LCD display panel

Peripherals – Liquid Crystal Display (LCD)

The LCD provides a versatile means of displaying alphanumeric data and messages (such as error codes, status messages, and user instructions).

The LCD can display 2 rows of 16 characters.

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


Embedded systems programming custom sensors for the use with atmel atmega8535 microcontrollers

Peripherals -Seven Segment display

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Embedded Systems Programming IIRichard Anthony, Computer Science, The University of Greenwich


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