Using the STK525
2-18
STK525 Hardware User Guide
7608A–AVR–04/06
Figure 2-16 . Microphone interface schematic
2.6.5
Data Flash Memory
For mass-storage class demonstration purposes, the STK525 provides an on-chip serial
Flash memory (AT45DB321x) connected to the AT90USBxxx Serial Port Interface
(SPI).
The data-flash chip select signal is connected to PortB bit 4 of the AT90USBxxx (See
Figure 2-17).
Figure 2-17 . On-board data flash schematic
2.6.6
Potentiometer
The cursor of a potentiometer is connected to ADC channel 1 of the AT90USBxxx.
3.3V
3.3V
3.3V
R23 100k
1
TP4
Mic
5
6
7
8
4
+
-
U4B
LMV358
3
2
1
8
4
+
-
U4A
LMV358
R27 0
R26 22k
R25
10k
R24 100k
+
C25
1uF
R21
100k
R28
100k
C22
220pF
+
C24 4.7uF
R20
2.2k
MIC1
MICROPHONE
R22
100k
3.3V
BUSY
1
RESET
2
WP
3
VCC
6
GND
7
CS
11
SCK
12
SI
13
SO
14
U2
AT45DB321C TSOP28
C15
100nF
PB[7..0]
R11
100k
PB4
3.3V
PB1
R10
100k
RESET
PB2
PB3
