Atmel STK502 manual 18. AREF Switch, 2.7.1.2 PF10 Switch

Using the STK502 Top Module
2.7.1.1 AREF Switch	The switch named AREF selects the input to the AREF-pin on the ATmega169.
	Figure 2-18. AREF Switch

From

STK500

AREF

AVR

AREF

STK502 VREF

STK502	Voltage refernce
	for the sensor

AREF

Switch

Positions:

￿ AREF: In this position the AREF from the STK500 is connected to the AREF pin on

	the ATmega169. This is the default position.
	￿ VREF: In this position the VREF from the 1.263V voltage reference on the STK502 is
	connected to the AREF pin on the ATmega169. Select this position in order to run the
	code in Application Note “AVR064: STK502 – A Temperature Monitoring System with
	LCD Output”
2.7.1.2 PF[1:0] Switch	The PF[1:0] switch selects the input to the PF1 and PF0 pins (ADC channel 1/0) on the
	ATmega169.
	Figure 2-19.PF[1:0] Switch

PORTF0

Sensor

pin 1

PORTF1

Sensor

pin 2

PF[1:0]

Switch

AVR

PF0 (ADC0)

PF1 (ADC1)

Positions:

￿PIN: In this position the PF0 and PF1 are from the PORTF on the STK502 are connected to the PF0 and PF1 on the ATmega169. Default position.

￿Sensor: In this position the pin 1 from the screw-terminal on the STK502 are connected to PF0 on the ATmega169, and the pin 2 from the screw-terminal are connected to PF1 on the ATmega169. Select this position in order to run the code in Application Note “AVR064: STK502 – A Temperature Monitoring System with LCD output”

In the sensor position both PF0 and PF1 are connected to the senor pins, regardless of using single ended or differential ADC-measurements in the application. This means that it's not possible to use PF1 as an ordinary I/O-port even though only PF0 (single ended) is used with the ADC.

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STK502 User Guide

2528A–AVR–11/02