AT90USBKEY2 Atmel, AT90USBKEY2 Datasheet - Page 10

• Manufacturer Part Number: AT90USBKEY2
• Description: KIT DEMO FOR AT90USB
• Manufacturer: Atmel

Specifications of AT90USBKEY2

• Main Purpose: USB Controller
• Embedded: *
• Utilized Ic / Part: AT90USB1286, AT90USB1287, AT90USB646, AT90USB647
• Primary Attributes: *
• Secondary Attributes: *
• Supplier: Atmel
• Architecture: 8/16-bit
• Interfaces: USB
• For Use With: ATSTK525 - KIT STARTER FOR AT90USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AT90USBKEY; AT90USBKEY

7627A–AVR–04/06
Using the AT90USBKey
2.4.3
2.4.4
2-10
LEDs
Temperature Sensor
The AT90USBKey includes 2 bi-color LEDs (green/red) implemented on one line. They
are connected to the high nibble of “Port D” of AT90USB (PORTD[4..7]).
To light on a LED, the corresponding port pin must drive a high level. To light off a LED,
the corresponding port pin must drive a low level.
Figure 2-7 . LEDs Implementation schematic
Table 2-1 . Leds references
The temperature sensor uses a thermistor (R29), or temperature-sensitive resistor. This
thermistor have a negative temperature coefficient (NTC), meaning the resistance goes
up as temperature goes down. Of all passive temperature measurement sensors,
thermistors have the highest sensitivity (resistance change per degree of temperature
change). Thermistors do not have a linear temperature/resistance curve.
The voltage over the NTC can be found using the A/D converter (connected to channel
0). See the AT90USB Datasheet for how to use the ADC. The thermistor value (R
calculate with the following expression:
R
T
Where:
=
LED Reference
(
R
H
⋅
V
D2
D5
ADC 0
R
R
V
VCC = Board power supply
T
H
ADC0
) V
LEDs
= Thermistor value (Ω) at T temperature (°Kelvin)
= Second resistor of the bridge -100 KΩ
⁄
(
= Voltage value on ADC-0 input (V)
CC
D2
D5
–
V
ADC 0
In-line Grouped LEDs
1k
1k
1k
1k
)
AT90USB Connection
R14
R17
R22
R23
PORTD.4
PORTD.5
PORTD.6
PORTD.7
PD4
PD5
PD6
PD7
AT90USBKey Hardware User Guide
±
10% at 25°C
PD[7..0]
Green
Green
Color
Red
Red
T
) is